Quick Summary
- One chart per model: Every crane has its own load chart showing rated capacity across different lift ranges and angles.
- Total load includes everything: Your load weight must include the object plus all lifting gear, hooks, rigging, ropes, and harnesses.
- Ideal conditions only: Rated capacities assume fully extended outriggers, properly prepared ground, minimal obstructions, and good weather.
- Read at the furthest point: Base your capacity on the furthest range of extension the lift will require.
- 75% is the critical threshold: A lift at 75% or more of the crane's capacity is a critical lift and needs a critical lift plan.
- Free help is available: Parker's Crane offers free on-site quotes and evaluations, plus lift plans.
What a Crane Load Chart Tells You
A load chart is the reference document for a crane's capabilities and limits. It covers the crane's dimensions and weight, its outrigger setup, and the maximum load it can handle at various combinations of boom extension and lift angle.
The maximum capacity advertised for any crane can only be reached under optimal conditions, which rarely occur on an active site. Ground stability, physical obstructions, and weather can all reduce what a crane can safely lift. For example, our Grove GMK5150L has a maximum capacity of 175 US tons, but that top figure does not apply at every boom length and angle. The load chart tells you what the crane can actually handle for the lift you are planning.
Step One: Calculate the Total Load Weight
The first step in understanding crane lifting capacity is determining exactly what you need to lift, how heavy it is, and where it needs to travel from and to. Your crane rental company will ask for the total weight of the load, and that number must be as accurate as possible.
Load calculations should account for the weight of everything the crane will pick up, including:
- The object being lifted
- All lifting gear
- Hooks and rigging
- Ropes and harnesses
- Beams and chains
- Any construction materials on the load
Ways to Find Your Load Weight
Start with the simplest method that applies to your load:
- Check for a marked weight on the object itself or its packaging.
- Review your records, design plans, or engineering paperwork.
- Look at the bill of sale or shipping label, which often lists weight.
- Contact the manufacturer for specifications on individual parts that you can add together.
- Use an industrial scale, often found in shipping and receiving departments.
- Attach a dynamometer directly to the rigging for an accurate reading before each lift.
- Calculate it manually by finding the object's volume and multiplying it by the weight per cubic foot of its material.
For a deeper walkthrough of each method, read our guide on how to calculate load before renting a crane.
Step Two: Review the Crane's Dimensions and Setup
The first section to look at on a load chart covers the crane itself. Each chart shows the crane's dimensions and weight, along with information on standard operating features such as outriggers. This data tells you how the crane will sit on your site and helps you identify space constraints and special site preparation needs.
If you need to work in a confined space that will not allow full outrigger deployment, the crane's stability changes and its maximum capacity drops significantly. Ground conditions also play a major role. Before your lift, evaluate whether the crane will sit on solid ground, bedrock, soft soil, or clay, and whether recent rain has affected the surface. Matting may be needed to support the crane on certain sites.
Our article on how to properly prep your site for crane arrival covers ground conditions, access, and clearances in detail.
Step Three: Determine Lift Range and Lift Angle
Before you look up a capacity figure, you need to know how the load will move. Cranes rarely lift loads straight up and down, so both range and angle shape your available capacity.
Lift Range
Lift range is how far the boom needs to extend to pick up and place the load, taking both distance and height into account. Calculate this carefully for every lift. When the load will travel through several positions, select your maximum capacity based on the furthest range of extension the lift will require.
Lift Angle
Lift angle plays a significant role in determining maximum capacity. As the boom extends further, the maximum capacity decreases. The angle places strain on the crane's stability, and exceeding the rated capacity for a given angle greatly increases the chance of tipping.
Step Four: Find the Rated Capacity on the Chart
With your load weight and lift path known, follow the chart's axes for distance and angle, and the point where they meet shows the maximum load weight for that configuration. Compare that figure to your total load, including all rigging.
This rated capacity represents the ideal lift, so factor in real site conditions before you finalize the plan.
Factors That Reduce Real-World Capacity
- Outrigger limitations: Partial outrigger extension in tight spaces lowers stability and capacity.
- Ground conditions: Soft, wet, or uneven ground can compromise the crane's footing.
- Obstructions: Buildings, structures, and overhead power lines may limit the boom's position.
- Wind and weather: Wind adds force to a suspended load, which is why a wind gauge (anemometer) is often used throughout critical lifts.
- Lift speed: Any movement adds force to the load, and those forces belong in your calculations.
- Side pull: Cranes are designed to lift within the vertical plane, and pulling a load from the side shifts the center of balance and increases the risk of tipping. Learn more in our article on side pull and how to avoid it.
When a Lift Becomes a Critical Lift
If your planned lift exceeds 75% of the crane's determined capacity, a critical lift plan must be formed and followed. Other conditions can also make a lift critical, including:
- The lift requires more than one crane
- The lift calls for atypical rigging or highly technical processes
- The load will be outside the operator's field of view at some point
- Damage to or loss of the load would cause significant financial consequences or substantial project delays
Critical lifts call for dedicated personnel, each focused on a single task. A typical team includes a certified rigger, a certified signal person, a certified operator, a site supervisor, and a certified lift director. Our guide to developing your critical lift plan explains the full process.
Selecting the Right Crane for Your Load
No matter the job, the right crane makes the work safer and smoother. Parker's Crane operates a fleet of well-maintained hydraulic truck cranes with a range of capacities:
- Grove GMK5150L: Up to 175 US tons, 197 ft main boom, 318.2 ft maximum tip height
- Grove TMS9000-2: Up to 115 US tons, 36 to 169 ft main boom, 263.4 ft maximum tip height
- Grove TMS9000E: Up to 110 US tons, 142 ft maximum tip height
- Grove TMS700E (two units): 50 to 60 US tons, 36 to 110 ft main boom, 212 ft maximum tip height
You can review full specifications on our crane list. When you call for a quote, have these details ready:
- Job location
- Set-up area
- Ground conditions
- Overhead obstructions
- Load dimensions
- Load weight
If you are new to the process, our step-by-step guide to renting a crane for the first time explains what to expect from the first call through lift day.
Frequently Asked Questions
Who needs to understand the crane load chart?
Everyone involved in the lift should understand the chosen crane's capabilities and limits, including operators, supervisors, and planners. A qualified crane operator understands load charts, crane limitations, and environmental factors. Every operator on the Parker's Crane team holds NCCCO certification.
Does the weight of the rigging count toward the load?
Yes. The crane lifts everything attached to the hook, so hooks, slings, ropes, harnesses, beams, chains, and any other lifting gear must be added to the weight of the object.
Can a crane lift its maximum rated capacity in any configuration?
No. Maximum capacity is reached only under optimal conditions and at specific configurations. As the boom extends further and the lift angle changes, the crane's capacity decreases.
What should I do if my lift is close to the crane's limit?
A lift at 75% or more of the crane's capacity is a critical lift, and it requires a formal critical lift plan. In many cases, selecting a larger crane provides a safer margin. Our team can help you evaluate both options.
Plan Your Next Lift With Confidence
Reading a crane load chart comes down to four steps: calculate the full load weight, understand the crane's setup requirements, determine your lift range and angle, and confirm the rated capacity for that configuration. Parker's Crane Service is a family-owned company that has served the Carolinas for over 40 years, with a Zero Accident Philosophy guiding every lift. If you would like help reading a load chart or choosing the right crane for your project, contact our team for a free on-site quote.