Crane Lift Calculator
A crane lift calculator helps riggers, lift supervisors, and project managers determine whether a proposed crane lift is within safe operational limits. The total lift weight includes not only the load itself but also rigging hardware, lifting beams, and the crane's own hook block. This total must be compared against the crane's rated capacity from the load chart at the actual working radius. This calculator determines the gross lift weight, calculates the utilization percentage against the crane's rated chart capacity, and flags whether the lift qualifies as a critical lift requiring an engineered lift plan. Always verify against the specific crane's load chart before executing any lift.
Crane lift calculation
Gross Lift Weight = Load + Rigging + Hook Block
Allowable Capacity = Chart Capacity x (De-rating% / 100)
Utilization = (Gross Lift / Chart Capacity) x 100
Critical lift if Utilization > 75% of chart capacity
The utilization is calculated against the full chart capacity per ASME B30.5 definitions. Lifts exceeding 75% of chart capacity are critical lifts and require an engineered lift plan.
Frequently asked questions
What is the rated capacity of a crane?
The rated capacity is the maximum load a crane is certified to lift at a specified boom length and radius combination, as shown on the crane's load chart. ASME B30.5 requires crane manufacturers to publish load charts based on structural and tipping stability limits. Rated capacities must never be exceeded.
What is lift radius in crane operations?
Lift radius (or working radius) is the horizontal distance from the crane's centerline of rotation to the center of the suspended load. As the radius increases, the crane's rated capacity decreases significantly. Always check the load chart for the specific radius and boom configuration being used.
What percentage of rated capacity should I use for crane lifts?
ASME B30.5 recommends keeping lifts within 75-85% of rated capacity for routine lifts. For critical lifts (defined as exceeding 75% of rated capacity, or involving multiple cranes), a formal lift plan is required. Many companies set a de-rating policy of 80% of the chart capacity for all lifts.
What is included in the total lift weight?
Total lift weight includes the weight of the load itself, all rigging hardware (slings, shackles, hooks, spreader bars), and any lifting attachments. The crane must also carry the weight of its own hook block and any auxiliary rigging. Deduct the hook block weight from the chart capacity to get the available net load capacity.
What is a critical lift?
A critical lift as defined by ASME B30.5 is any lift that exceeds 75% of the crane's rated capacity at the working radius, involves tandem lifting with more than one crane, or involves lifting personnel. Critical lifts require an engineered lift plan, a lift director, and enhanced pre-lift inspections.
Official sources
- ASME: ASME B30.5 Mobile and Locomotive Cranes Safety Standard.
- OSHA: OSHA 29 CFR 1926 Subpart CC - Cranes and Derricks in Construction.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.