How to Read a Crane Load Chart

To read a crane load chart, confirm the configuration in the header (counterweight, outriggers or on-rubber), find your boom-length column, and read down to your load radius, using the next greater radius when you fall between rows. That number is gross capacity: subtract the hook block, ball, rope and jib, and the load plus rigging must fit under the net.

What a Crane Load Chart Actually Is

A crane load chart is the manufacturer’s published statement of how much a specific machine can lift in every configuration it can be set up in. It is not a suggestion or a rule of thumb. It is the engineering limit. Operate outside it and cranes tip over and crews get killed. Walk through a real load chart, line by line.

Every crane ships with its own chart. It is usually a thick booklet or a laminated set of pages stored in the cab, and it is unique down to the options on that machine. A crane capacity chart for one 90-ton all-terrain is worthless for the 90-ton all-terrain parked next to it if the counterweight, boom, or tire rating differs.

Here is why this skill matters so much: a crane’s capacity is not a single number. The same machine that lifts 80,000 pounds at a tight radius might lift only a few thousand pounds with the boom stretched out and swung over the side. The chart is the map of every one of those points.

Learning to read it well is the difference between an operator who can tell you in ten seconds whether a pick is safe and one who finds out the hard way. Reading the chart is also a core competency on the NCCCO written and practical exams, and it runs through everything we teach at 3P Safety Crane & Rigging Training.

• It is machine-specific: tied to that crane’s boom, counterweight, outriggers, and tire rating.
• It is configuration-specific: a different setup means a different page and a different number.
• It is the legal and engineering limit: not a target to push against.

The Anatomy of a Load Chart – Every Section Explained

Open a manufacturer’s load chart booklet and it can look like a wall of numbers. It is not. It is a handful of repeating elements, and once you know what each one means, the whole document opens up. Here is the anatomy of a typical mobile crane load chart.

• The header / capacity block. Up top you’ll find the machine model, the boom type and length range, the counterweight the chart applies to, and the outrigger or crawler setup it assumes. Read this first, every time. If the chart is for 18,000 lb of counterweight and your crane has 12,000 lb on, you are reading the wrong chart. Every number below it is a lie.
• The radius column. This is usually the far-left column – the horizontal distance, in feet, from the crane’s center of rotation to the center of the load. Radius is the single biggest driver of capacity. As radius goes up, capacity comes down fast.
• Boom-length columns. Across the top, capacities are listed by main boom length: 40 ft, 60 ft, 80 ft, and on up. You find your boom length, then read down to your radius.
• The capacity values. Where your radius row meets your boom-length column is the rated gross capacity in pounds for that exact setup. That is the total the crane can support at that point, including everything hanging below the boom tip.
• The stability line / structural shading. Most charts draw a bold line, or shade or bold the numbers, to separate capacities limited by tipping (stability) from those limited by structural strength. Below the line you’re stability-governed. Above it the steel is the limit. Knowing which side you’re on changes how the crane will warn you when you overload it.
• Notes, footnotes, and deduction tables. The fine print is not optional. It lists weight deductions for the hook block, headache ball, jib, and wire rope, plus rules for parts of line, working over front versus side, defeating modes, and wind limits.

The discipline is always the same order of operations. Confirm the configuration in the header, find your boom length, read down to your radius, and that’s your gross capacity – which you then convert to net. We drill this exact sequence with real charts in our NCCCO Mobile Crane Operator certification prep until it’s automatic. For one boom-truck pick worked start to finish, see our step-by-step guide on how to read a crane load chart.

Gross Capacity vs. Net Capacity – The Deduction Math That Trips Operators Up

This is where the most dangerous mistakes happen. It is the single most failed concept for under-prepared candidates. The number printed in the chart is gross capacity – the total load the crane can carry at that radius and boom length. But that gross number has to support everything hanging off the boom tip, not just your load.

To find what you can actually pick – the net capacity – you subtract the weight of all the rigging hardware between the boom tip and the load.

Net capacity = Gross capacity (from the chart) – the sum of all deductions.

The deductions almost always include:

• The hook block. On a big machine this alone can be 1,000 to 2,000+ pounds.
• The headache ball (overhaul ball) if you’re running single-part line.
• The wire rope hanging below the tip. On a long, high boom that weight is not trivial.
• An erected jib or boom extension, even when stowed or not in use. A jib mounted on the side of the boom is dead weight the chart accounts for.
• Auxiliary heads, slings, spreader bars, and any other below-the-hook rigging.

Here’s the part operators forget under pressure: the slings, shackles, and spreader bars are part of the load too. A 10,000 lb beam picked with a 600 lb spreader bar and 200 lb of slings is a 10,800 lb load against your net capacity. If your net is 10,500, you cannot make that pick, full stop – even though the load itself is “under” the number.

We teach candidates to build the full tally every time. Chart gross, minus block, minus ball, minus jib, minus rope, equals net available. Then the gross weight of the load plus all rigging has to fit under that net. Getting fluent in this is exactly why our Qualified Rigger training pairs so naturally with operator certification. The rigger and operator have to agree on the same numbers.

Radius and Why It Drives Everything

If you remember one thing about load charts, make it this: radius is king. Radius is the horizontal distance from the crane’s center of rotation to the center of the load, and it is the dominant factor in how much you can lift. The further the load gets from the machine, the more leverage it has to tip the crane, so chart capacity drops sharply to compensate. It is not a gentle slope. Near the limits of the boom it can fall off a cliff.

Two things constantly bite operators on radius.

• Loaded radius is bigger than empty radius. When you pick a load, the boom deflects – it bends down and out under the weight – and the load also pulls forward. So your actual working radius once the load is in the air is larger than the radius you measured to the empty hook. A pick that looked good at 30 feet can settle in at 33 or 34 feet loaded, and at that new radius your capacity is lower. Smart operators read the chart for the loaded radius they’ll end up at, not the one they start at.
• You always round the wrong way – in your favor for safety. If your radius falls between two rows on the chart, say you’re at 47 feet and the chart lists 45 and 50, you use the next-greater radius: the 50-foot row, the smaller capacity. Same with boom angle and length. When in doubt, read the more conservative line. The chart is not the place to round optimistically.

Because radius matters so much, the operator and the signal person have to communicate clearly about where the load is going and how far out it will swing. That coordination, and the standard signals behind it, is the backbone of our Signal Person certification. A crane is a system, and the load chart only holds if everyone on the lift respects the radius.

Boom Length, Boom Angle, and the Range Diagram

Capacity isn’t governed by radius alone. It’s the combination of boom length, boom angle, and radius, and those three are locked together by geometry. For any given boom length, a steeper boom angle pulls the load in closer – shorter radius, more capacity. Lowering the boom pushes the load out – longer radius, less capacity. You can’t change one without the others moving, which is why operators have to think in all three dimensions at once.

This is where the range diagram comes in. Most charts include one – a scaled side-view drawing of the crane with arcs showing each boom length swept through its range of angles. It answers the geometry questions the capacity table alone can’t:

• Will it reach? The diagram shows the height you can achieve at a given radius for each boom length. That’s critical for clearing a building edge or setting steel at elevation.
• What boom angle and length do I need to put the hook over the load at the radius and height the lift requires?
• Do I have clearance over obstructions, and how much boom is above the load once it’s set?

The workflow is simple. Use the range diagram to plan the geometry – pick the boom length and angle that put the hook where it needs to be. Then use the capacity table to confirm the machine can actually lift the load at that radius. Both have to check out. A configuration that reaches but can’t lift is useless. One that lifts but can’t reach never gets a chance.

Operators who learn this on real iron, planning real picks, internalize it far faster than anyone working from a worksheet. That’s the entire philosophy behind our hands-on Crane Operator School in Goldsboro, NC.

Configuration: Counterweight, Outriggers, Ground Bearing, and On-Rubber Picks

A single crane has many load charts, not one. Every change to its setup changes its capacity, and the manufacturer publishes a separate chart for each legitimate configuration. Reading the right chart for the configuration you’re actually in is non-negotiable. The big variables are these.

• Counterweight. Cranes are rated for specific counterweight packages. Run less counterweight than the chart assumes and you do not get “close enough” capacity. You get a crane that will tip earlier than the numbers say. Always match the chart to the counterweight actually installed.
• Outrigger position. Many mobile cranes have multiple outrigger settings – fully extended, intermediate (often a defined mid setting), and fully retracted – with a separate chart or column for each. Fully extended outriggers give the widest, strongest base and the highest capacities. A partially extended setup, common on tight sites, can cut capacity dramatically, especially over the side.
• On outriggers vs. on rubber. Lifting on fully set, leveled outriggers is one chart. Lifting on rubber – on the tires, no outriggers – is a completely different and far more restrictive chart. On-rubber picks have their own rules: tire pressure, often a very limited or near-zero swing, slow travel, and sometimes a defined area you can work in. Never read an on-outrigger number and then lift on rubber.
• Over the front, side, or rear. A crane is most stable lifting over the end with the widest, best-supported base, frequently the rear over the counterweight or a defined “over front” zone on outriggers. It is least stable over the side. Many charts give a reduced “360-degree” capacity for swinging all the way around, because the weakest direction governs once you rotate.

There’s one more piece of the setup the capacity table never shows you: whether the ground can carry the crane. A perfectly executed pick that’s well within the load chart will still put a machine on its side if an outrigger float punches through soft fill, settles into a buried utility trench, or sits over a hidden void. The chart tells you what the crane can lift, not whether the dirt will hold it.

Working operators and lift planners think in terms of ground bearing pressure – the force each outrigger or crawler track transmits to the soil versus the soil’s allowable bearing capacity. Because of leverage, the corner outrigger nearest a heavy pick over the side can see a force far greater than the load’s own weight. That’s why “the load is light” is never the whole story. Pads and cribbing spread that force over a bigger footprint to lower the pressure, while backfill, slopes, excavation edges, and buried structures all cut bearing capacity.

This ties directly to OSHA’s Subpart CC requirements around ground conditions, which is why we never treat the load chart as a stand-alone document. A safe lift is the chart, the configuration, and the ground all agreeing. When we bring employer-based crane training to a jobsite, we train operators on their own machines, in their own configurations, on the ground they actually set up on – so the chart they read in class is the chart they’ll read on the job.

Stability vs. Structural Limits – Why Exceeding the Chart Causes Tip-Overs

Understanding why capacities are what they are makes you a far better chart reader. Every number on the chart is limited by one of two things: stability (will the crane tip?) or structural strength (will the boom, jib, or another component fail?). The chart’s bold stability line tells you which one governs at each point.

• Stability-governed capacities sit at longer radii, below the line. They are set as a percentage of the tipping load – the load that would actually start to lift the crane off its supports. Mobile cranes on outriggers are commonly rated to a defined fraction of that tipping load, with crawler and on-rubber ratings often set more conservatively, so there’s a built-in margin before the machine goes over.
• Structurally-governed capacities sit at shorter radii, above the line. They are limited by the strength of the steel – the boom, the jib, the hoist system. Here the crane will not warn you by getting tippy. It can fail catastrophically and suddenly with all four outriggers still planted. That’s why short-radius overloads can be so deadly: the operator feels stable right up until something breaks.

Now the headline. Exceeding the load chart is one of the leading causes of mobile crane tip-overs and structural failures. When an operator picks a load heavier than the rated capacity for the radius – by guessing the weight, forgetting the rigging deductions, drifting out to a longer radius than planned, or reading the wrong configuration’s chart – the safety margin the rating is built on disappears.

Push a stability-limited point and the crane tips. Push a structurally-limited point and steel fails. Either way, the chart was right and the operator was wrong. That hard reality is exactly why load-chart competency is tested so heavily on the NCCCO exam and why we hammer it in every class. A crane operator who respects the chart, and knows which side of the stability line they’re on, is an operator who goes home. Anyone new to the trade should start with our guide on how to become a crane operator and build this skill from day one.

Load Charts and the NCCCO Exam – Where This Skill Gets Tested

There’s a reason this page is so detailed. Load-chart reading is the single highest-yield, most-failed area of the NCCCO written exam, and it’s woven through the practical too. Candidates who can confidently read a chart pass. Those who can’t, don’t.

On the written side, expect to be given a chart and asked to determine capacity at a stated radius and boom length, account for deductions to find net capacity, and decide whether a described pick is within limits. The math isn’t hard. It’s the discipline of doing it the same way every time, under a clock, that separates passers from the rest.

On the practical exam, the chart shows up indirectly but unavoidably. You’re expected to set up and operate the crane as a competent operator who understands its limits, and the whole exercise assumes you’d never put the machine in a position the chart doesn’t support. The standards behind all of this trace back to OSHA 1926.1427 operator certification and the ASME B30 consensus standards. That’s why certification – not just “training” – is what employers and general contractors require before they hand you the keys. The broader regulatory picture is laid out on OSHA’s Cranes & Derricks page.

Our prep is built around exactly this. We put real manufacturer charts in your hands and drill the full sequence – confirm configuration, find boom length, read down to radius, subtract every deduction, compare to the load plus rigging – until it’s automatic and fast. We run open-enrollment NCCCO classes on a rolling monthly calendar at our school at 309 N William St, Goldsboro, NC 27530 using real working cranes: Mobile Crane Operator (4-day), Qualified Rigger (3-day), and Signal Person (1-day). Check the live class schedule to grab a date. For crews, we bring the same load-chart-first instruction to your jobsite nationwide.

The NCCCO Load Chart Manuals: LAT, TSS, and TLL

Since January 2023 every CCO Mobile Crane Operator written exam has used generic load chart manuals instead of manufacturer-specific charts. CCO publishes one manual per designation, each adapted from a real manufacturer’s chart and reissued under CCO’s own cover: a lattice-boom crane for LAT (the single lattice designation that covers crawler- and truck-mounted machines), a Manitex boom truck for TSS (telescopic boom, fixed cab), and a Link-Belt rough-terrain crane for TLL (telescopic boom, swing cab). The exam’s load chart questions are written against these exact pages, so candidates should study the manual for their designation, not the chart from the crane at work.

• Lattice Boom Crane (LAT) load chart manual, 28 pages: range diagram, boom and jib combinations, capacity tables by boom length and radius, deductions.
• Telescopic Boom Crane, Fixed Cab (TSS) load chart manual, 8 pages: one main-boom table (26 to 68 ft), a jib table, deductions for blocks and the stowed jib, allowable line pull by parts of line.
• Telescopic Boom Crane, Swing Cab (TLL) load chart manual, 18 pages: setup notes, two boom modes, 360° and over-front columns, fly and tip deductions, pontoon loads and outrigger spread.

All three are free from CCO’s load chart page, revision 12/22 (reissued 01/23). Print them. Candidates who pass the load chart section comfortably are the ones who have worked the tables on paper until the notes on page two are second nature, because the notes are where the exam hides its questions.

Worked Load Chart Problems From the NCCCO Manuals

Three problems, worked the way the exam expects. Each uses figures printed in the current CCO manuals; every step is one you can check against the page cited.

Problem 1 (TLL): gross to net capacity with a stowed fly

Setup. Link-Belt swing-cab crane, Boom Mode “A,” fully extended outriggers, 45-ft main boom, load radius 25 ft, lifting 360°. A 60-ton hook block is reeved, and the 34-ft offset fly is stowed on the boom base. The load is a 50,000-lb vessel with 600 lb of slings and shackles.

1. Enter the 35.5-to-45-ft table on the 45-ft boom side at the 25-ft radius row, 360° column: 55,100 lb gross capacity. (The over-front column reads 55,600 lb, but the pick swings through the side, so 360° governs.)
2. Deduct the load handling equipment from the deduction table on page 5: 60-ton hook block, 1,100 lb; 34-ft offset fly stowed on boom base, 900 lb. Total deductions 2,000 lb.
3. Net capacity: 55,100 − 2,000 = 53,100 lb.
4. Total load: 50,000 + 600 = 50,600 lb. Slings and rigging are part of the load, never a deduction.
5. 50,600 lb is within 53,100 lb. The lift is within the chart at about 95% of net capacity, which is legal and also the point where a critical-lift plan, a confirmed radius, and a level crane stop being formalities.

Problem 2 (TLL): boom length and radius that are not in the table

Setup. Same crane and configuration, but the operator scoped the boom to 50 ft and the measured radius is 27 ft.

1. The 50-ft boom length is not listed; the table shows 45 ft and 55 ft. The TLL notes say to use the rating for the next longer or next shorter boom length, whichever is smaller. At 25 ft the 45-ft boom rates 55,100 lb and the 55-ft boom rates 44,200 lb, so the 55-ft boom governs.
2. The 27-ft radius is not listed either. Radius never rounds down: use the next larger radius, 30 ft. On the 55-ft boom, 30-ft radius, 360°: 37,800 lb gross.
3. Apply the same 2,000 lb of deductions: net 35,800 lb. The 50,600-lb load from Problem 1 is now far outside the chart. Two feet of radius and five feet of boom took away a third of the capacity, which is why the loaded boom angle and the radius get measured, not estimated.

Problem 3 (TSS): a boom truck with a stowed jib

Setup. Manitex fixed-cab boom truck, outriggers and stabilizers extended, 38-ft boom, 20-ft radius, double-sheave load block, 23-ft jib stowed. The load is an 8,900-lb rooftop unit with 250 lb of rigging.

1. Main boom table, 38-ft boom column, 20-ft radius row: 10,350 lb gross. The loaded boom angle printed beside it (57°) is the angle after the load is on; the boom angle before loading has to be higher to allow for deflection.
2. Deductions from page 3 and the stowed-jib row under the table: double-sheave load block, 350 lb; jib stowed with a 38-ft boom, 330 lb. Total 680 lb.
3. Net capacity: 10,350 − 680 = 9,670 lb.
4. Total load: 8,900 + 250 = 9,150 lb. Inside the chart, at about 95% of net.
5. Check the fine print: this crane’s note 7 says that for boom lengths not shown you use the next longer boom length, and for radii not shown the next longer radius. That is not the same rule as the Link-Belt chart in Problem 2, and the exam will test whether you read the note on the chart in front of you rather than the one you remember.

Three habits carry all three problems: find the configuration before the number, deduct equipment but add rigging, and never interpolate between rows. The NCCCO practice test has more load chart items in the exam’s own phrasing, and our mobile crane certification classes work the manuals on paper before anyone touches the crane.

Master the Load Chart With 3P Safety

3P Safety Crane & Rigging Training is founder-led by Patrick Salazar – an NCCCO-certified mobile crane operator across the LBC, TLL, and TSS designations, a tower crane operator, a certified crane inspector, a lift director, and an OSHA 500 outreach trainer. When you learn load charts from us, you’re learning from someone who has read them in the seat to make real picks, inspected the machines they govern, and planned the lifts they protect. Not a classroom-only instructor reciting theory. That’s the difference between knowing what a load chart is and knowing how to live by one.

Whether you need one operator who can confidently work a crane capacity chart on the NCCCO exam, or a full crew trained to read charts on your own iron, we deliver real hands-on instruction at our Goldsboro, NC school or on your jobsite anywhere in the country. Call (252) 274-0583 or request a quote or enroll, and we’ll build a load-chart-first program around your operation. Founder-led, field-credentialed, and serious about sending operators home safe.

Frequently Asked Questions

What is the difference between gross and net capacity on a crane load chart?

Gross capacity is the number printed in the load chart for a given radius and boom length – the total weight the crane can support at that point. Net capacity is what you can actually pick, and you get it by subtracting all the deductions from gross: the hook block, headache ball, wire rope below the boom tip, any erected jib or boom extension (even when stowed), and any other below-the-boom-tip hardware. Then remember that your slings, shackles, and spreader bars count as part of the load. So a pick is only safe when the weight of the load PLUS all rigging fits under the net capacity. Forgetting the deductions, or forgetting the rigging weight, is one of the most common and dangerous load-chart mistakes – and a heavily tested concept on the NCCCO exam.

Why does a crane’s capacity drop so much as the load moves farther out?

Because radius – the horizontal distance from the crane’s center of rotation to the center of the load – is the dominant factor in capacity. The farther the load is from the machine, the more leverage it has to tip the crane, so the rated capacity falls sharply to keep a safe margin. It’s also why loaded radius matters more than empty radius: when you pick a load the boom deflects and the load pulls forward, so your actual working radius ends up larger than what you measured to the empty hook, at a lower capacity. Good operators read the chart for the loaded radius they’ll end up at, and when a radius falls between two chart rows, they use the next-greater radius and the smaller capacity.

Why does one crane have so many different load charts?

Because capacity changes with configuration, and the manufacturer publishes a separate chart for each legitimate setup. The big variables are counterweight package, outrigger position (fully extended, intermediate, or retracted), whether you’re lifting on outriggers or on rubber (on the tires), and the direction of the lift – over the front or rear versus over the side. Lifting on rubber is a completely different and far more restrictive chart than lifting on fully set outriggers. Reading the wrong chart for your actual configuration is the same as having no chart at all, because the numbers no longer apply. The first discipline of chart reading is always confirming the configuration in the header before you trust a single capacity value.

What is a range diagram and how is it different from the capacity table?

A range diagram is a scaled side-view drawing of the crane showing each boom length swept through its range of angles, so you can see the height and reach you’ll get at a given radius. The capacity table tells you how much you can lift; the range diagram tells you whether the geometry works – whether the boom will reach the required height and radius and clear obstructions. The two work together: you use the range diagram to plan the boom length and angle that put the hook where the lift needs it, then use the capacity table to confirm the crane can actually lift the load at that radius. Both have to check out. A setup that reaches but can’t lift, or lifts but can’t reach, is no good.

Why is exceeding the load chart such a common cause of crane tip-overs?

Because every capacity on the chart is set with a built-in safety margin against either tipping (stability) or component failure (structure), and overloading erases that margin. Stability-governed capacities, usually at longer radii, are rated to a fraction of the load that would actually start to tip the crane – exceed them and the machine goes over. Structurally-governed capacities, usually at shorter radii, are limited by the strength of the boom, jib, and hoist system – exceed them and steel can fail suddenly with all the outriggers still down, no tippy warning at all. Operators overload by guessing the load weight, forgetting rigging deductions, drifting out to a longer radius than planned, or reading the wrong configuration’s chart. In every case the chart was right and the lift was wrong, which is exactly why load-chart competency is tested so hard on the NCCCO exam.

Does 3P Safety teach load-chart reading, and how do I sign up?

Yes – load-chart reading is central to our NCCCO prep because it’s the highest-yield, most-failed part of the written exam and the foundation of safe operation. We put real manufacturer charts in your hands and drill the full sequence until it’s automatic: confirm the configuration, find your boom length, read down to your radius, subtract every deduction, and compare net capacity to the load plus all rigging. We run open-enrollment NCCCO classes on a rolling monthly calendar at our Goldsboro, NC school using real working cranes, and we bring the same instruction to employer jobsites nationwide on your own equipment. Call (252) 274-0583 or use our contact page to enroll or request a quote for your crew.

Authoritative References