Crane Load Chart Reading Guide

A crane load chart tells the operator exactly how much weight the crane can safely lift at every combination of boom length and radius. Misreading or ignoring the load chart is a leading factor in crane tip-overs, structural failures and dropped loads - incidents that routinely kill and seriously injure workers. OSHA requires crane operators to understand and follow the load chart for their specific machine (29 CFR 1926.1417 for construction, 29 CFR 1910.180 for general industry), and ASME B30.5 reinforces that the rated capacity shown on the load chart must never be exceeded.

This guide breaks down how to read a crane load chart step by step, explains the variables that affect crane capacity and highlights the most common mistakes that lead to overloading.

What Is a Crane Load Chart?

A crane load chart is a table or set of tables provided by the crane manufacturer that lists the maximum allowable load (in pounds or tons) for each combination of boom length and operating radius. The chart is specific to the exact make, model and configuration of the crane. Two cranes of the same model can have different load charts if they have different counterweight configurations or boom options.

Load charts are typically posted inside the crane cab and included in the crane's operating manual. For detailed rigging and load chart resources, see our crane safety rigging and load charts guide.

Why Load Charts Matter

A crane's capacity changes dramatically as conditions change. A mobile crane that can lift 100 tons at a 10-foot radius might only lift 15 tons at a 60-foot radius. Operating without consulting the load chart - or misreading it by one row or column - can put the crane beyond its tipping point or exceed the structural limits of the boom. Either scenario can be fatal.

Key Load Chart Variables

Before you can read a load chart, you need to understand the variables that define each cell in the table.

Operating Radius

The operating radius is the horizontal distance from the center of rotation (the crane's swing center pin) to the center of the load being lifted. This is the most critical variable in any lift plan. As the radius increases, the crane's capacity decreases - often dramatically. A small change in radius (moving the load just a few feet farther from the crane) can reduce capacity by thousands of pounds.

Important: The radius is measured to where the load hangs, not to the boom tip. If the load swings outward during the lift, the effective radius increases and the crane may be overloaded even though it was within capacity when the lift began.

Boom Length

The boom length is the distance from the boom pivot point (boom foot pin) to the boom tip. Telescopic cranes have variable boom lengths and the load chart provides capacity ratings for each available boom extension. Longer boom lengths reduce capacity because the longer boom weighs more and creates a greater overturning moment.

Boom Angle

The boom angle is measured from horizontal. Higher boom angles correspond to shorter radii and higher capacities. Some load charts are organized by boom angle rather than radius, though radius-based charts are more common for mobile cranes. If the chart shows boom angle, you can calculate radius using the boom length and angle: radius = boom length x cosine(boom angle) + distance from swing center to boom foot pin.

Quadrant of Operation (Over Side, Over Rear, Over Front)

Many mobile crane load charts provide different capacity ratings depending on which direction the crane is lifting relative to the carrier (truck body). Lifting "over the rear" (over the counterweight) typically provides the highest capacity. Lifting "over the side" provides lower capacity because the crane's stability is reduced. Lifting "over the front" (over the cab) usually has the lowest capacity. Always use the correct quadrant chart for your planned lift direction.

On Outriggers vs. On Rubber

Hydraulic truck cranes and rough-terrain cranes have different load charts for "on outriggers" (outriggers fully extended and set) versus "on rubber" (operating on tires without outriggers). Capacity on outriggers is significantly higher. Some charts also provide ratings for partially extended outriggers, though many manufacturers and lift plans require full extension for all lifts. Never assume the outrigger configuration - check which chart applies to your setup.

Counterweight Configuration

Large mobile cranes and crawler cranes operate with removable counterweight blocks. The load chart specifies the counterweight configuration (in pounds or tons) that corresponds to the rated capacities in the table. If your crane has less counterweight installed than the chart assumes, the actual capacity is lower than what the chart shows. Verify counterweight before every lift.

Reading a Load Chart Step by Step

Step 1: Identify the Correct Chart

Most crane manuals contain multiple load charts for different configurations. Select the chart that matches your crane's actual setup: boom type (main boom vs. jib), outrigger position, counterweight installed and quadrant of operation. Using the wrong chart is one of the most common and dangerous mistakes.

Step 2: Determine Your Radius

Calculate or measure the operating radius for your lift. This is the horizontal distance from the crane's center of rotation to the point where the hook will be positioned over the load. If the crane will need to swing or change radius during the lift, determine the maximum radius that will occur and use that for planning.

Step 3: Determine Your Boom Length

Identify the boom length needed to reach the pick point at the planned radius and lift height. Use the shortest boom length that achieves the required reach, because shorter booms provide higher capacity.

Step 4: Find the Intersection

Locate your radius on the left column of the chart and your boom length across the top row (or vice versa, depending on chart format). The cell at the intersection shows the maximum rated capacity for that combination. If your exact radius or boom length falls between values shown on the chart, use the next larger radius and next longer boom length - always round in the direction that gives the lower (more conservative) capacity.

Step 5: Deduct for Rigging and Below-the-Hook Equipment

The rated capacity on the load chart includes everything hanging from the boom tip: the hook block, wire rope, slings, shackles, spreader bars, personnel baskets and the load itself. You must subtract the weight of all rigging components from the chart capacity to determine the actual load weight you can lift.

Common deductions:

• Hook block - typically 200 to 2,000+ pounds depending on the crane size
• Wire rope (running lines from the boom tip to the hook) - weight per foot multiplied by the number of parts of line and the distance from boom tip to hook
• Slings, shackles, spreader beams and other rigging hardware
• Any below-the-hook lifting devices (magnets, vacuum lifters, personnel platforms)

Step 6: Apply Reduction Factors

Several conditions require further capacity reductions beyond what the chart shows:

• Wind - Wind loads on the boom and load reduce effective capacity; most lift plans require reduced operations or shutdown above specific wind speeds
• Dynamic loading - Sudden stops, starts or swings create dynamic forces that exceed the static load weight
• Ground conditions - Soft ground, slopes or uneven surfaces reduce the effectiveness of outriggers and tracks; the chart assumes a firm, level surface
• Multi-crane lifts - When two or more cranes share a load, each crane's capacity must be derated per the lift plan (typically to 75% of chart capacity)

Step 7: Verify the Safety Margin

Industry best practice requires a minimum safety margin. The total weight of the load plus all rigging should not exceed 75% to 85% of the crane's rated capacity for routine lifts. Critical lifts (over occupied buildings, near power lines, with personnel baskets or involving irreplaceable loads) typically require the total load to stay below 75% of chart capacity. Your lift plan should specify the acceptable load percentage.

Crane Load Chart Example

Consider a simplified example for a 50-ton hydraulic truck crane on fully extended outriggers, lifting over the side:

In this example, if you need to pick a load at a 30-foot radius with a 65-foot boom, the chart shows a rated capacity of 28,000 pounds. After deducting 1,500 pounds for the hook block and rigging, your maximum load weight is 26,500 pounds. Applying an 85% utilization limit, you should not lift more than approximately 22,500 pounds in this configuration for a routine lift.

Common Load Chart Mistakes

• Using the wrong chart - Selecting the over-rear chart when actually lifting over the side, or using full-outrigger ratings when outriggers are only partially extended
• Forgetting rigging deductions - Treating the chart capacity as the allowable load weight without subtracting hook block, wire rope and rigging hardware
• Ignoring radius changes during the lift - A load picked at 20 feet of radius that swings to 25 feet during travel may exceed the rated capacity at the new radius
• Estimating load weight - Guessing instead of calculating or weighing the load; always use verified weights from shipping documents, engineering drawings or a crane scale
• Not accounting for ground conditions - Chart capacities assume firm, level ground; soft or sloped surfaces dramatically reduce stability

Keep Load Charts Accessible and Current

Load charts must be available in the crane cab at all times. If the original chart is damaged or illegible, obtain a replacement from the manufacturer. Store digital copies in your document management system so lift planners and safety personnel can access them during pre-lift planning. Never use a load chart from a different crane model or configuration, even if the cranes appear identical.

Lift Smarter with the Right Tools

Reading a crane load chart accurately is a fundamental skill for every crane operator, rigger and lift planner. Pair that skill with thorough lift planning, verified load weights and properly maintained equipment to prevent overloading incidents. Make Safety Easy helps you store load charts, manage crane inspection records and document lift plans in a single platform. Request a demo to see how our tools support your crane operations, or view pricing to choose the right plan for your team.