Gross vs net capacity: the formulas
Here, G is the gross rating from the correct chart cell for your crane's configuration. D is the sum of all deductions required by that chart's notes. N is the net capacity available for the payload alone. Payload excludes the gear entered as deductions.
- Total deductions: D = d₁ + d₂ + … + dₙ.
- Net payload capacity: N = G − D.
- Remaining arithmetic capacity: N − payload. A negative value means the payload exceeds net.
- Percent of net capacity: payload ÷ N × 100, only when N > 0.
These are arithmetic definitions, also demonstrated in Boom Angle's original synthetic practice-chart specification and exercises. They do not derive a crane's rating. Your crane's own chart and notes determine the correct rating, what it includes and the required deductions. If the starting value already excludes an item, subtracting it again would double count.
Which deductions belong in the worksheet?
Review the hook block, headache ball, slings, shackles, spreader or lifting beam, jib position, jib extensions, load-line weight and any other item required by the chart notes. Enter chart-specified allowances where required; a jib deduction need not equal its physical weight. An erected jib may require a different chart or restriction, so subtracting its weight alone does not establish capacity. Add rows for other applicable items, and avoid counting a rigging total together with its individual parts.
Confirm the crane, chart revision, loaded radius, boom length, counterweight, support setup and permitted lift area before entering G. Follow the chart's rule for dimensions between listed entries; this worksheet provides no real-chart lookup or interpolation rule.
Worked crane load chart example: invented Practice A
The invented Practice A chart at exactly 30 ft loaded radius and 80 ft main boom gives 24,000 lb gross. Its fictional setup is 360° on fully extended outriggers, standard counterweight, level on firm support and stationary main-boom lifting with an unloaded stowed jib. Subtract a 600 lb hook block, 800 lb stowed jib allowance and 200 lb slings. No other suspended gear is present in this example.
D = 600 + 800 + 200 = 1,600 lb. N = 24,000 − 1,600 = 22,400 lb. A 16,800 lb payload leaves 22,400 − 16,800 = 5,600 lb and uses 16,800 ÷ 22,400 × 100 = 75% of net capacity. Total suspended weight divided by gross would instead be (16,800 + 1,600) ÷ 24,000 × 100 ≈ 76.667%; the measures differ.
Choose “Load invented worked example” above to inspect the labeled chart and change the deductions or payload. All chart values and allowances in that mode come from our existing Synthetic practice-chart specification v1, invented for teaching on 17 October 2026. No manufacturer's chart, NCCCO material or real or recalled exam question is reproduced.
Structural vs stability ratings and the bold line
A structural rating concerns the strength limits of the crane's components. A stability rating concerns resistance to overturning in the specified configuration. Both constrain lifting capacity. OSHA's 1926.1433(b)(1)–(2) distinguishes these rating bases; this worksheet cannot calculate either rating from crane geometry.
Where a chart uses a bold line to distinguish rating bases, read that chart's legend to identify each side. In our invented charts, S above the stepped line is structural and T below is stability. The line is a change in the governing limit, never a safe/unsafe divider or permission to exceed a rating. Your crane's own chart is the authority for its markings and limits.
Operating and configuration checks
OSHA 29 CFR 1926.1417(a), (c)(1), (o) addresses applicable manufacturer procedures, operator access to charts and procedures, load-weight verification and rated-capacity compliance. A correct subtraction cannot establish that the selected cell or load weight is correct.
OSHA 29 CFR 1926.1404(m), (q) addresses component configuration and outrigger/stabilizer setup, including manufacturer-permitted deployment specified in the chart. The assembly/disassembly rigging provisions in (r) have their own scope. This worksheet does not verify assembly, rigging capacity or setup compliance.
Check against your applicable code edition, procedure and the responsible inspector/engineer. Confirm the chart notes, lift plan and all equipment and site limits with the responsible qualified personnel. No percentage here accounts for changing radius, ground bearing, dynamic effects, wind, reeving or line-pull limits.
Net capacity calculator FAQ
How do I get net capacity from gross capacity?
Net capacity N = G − D, where G is the gross rating from your crane's own chart cell and D is the sum of the deductions that chart's notes require. In the invented Practice A example, G = 24,000 lb and D = 600 + 800 + 200 = 1,600 lb, so N = 22,400 lb.
How is the percent of net capacity worked out?
Payload ÷ N × 100, only when N is above zero. A 16,800 lb payload against 22,400 lb net leaves 5,600 lb and uses 75%. Total suspended weight divided by gross gives a different number, (16,800 + 1,600) ÷ 24,000 × 100 ≈ 76.667%, so say which measure you mean.
Which deductions belong in the worksheet?
The ones your chart's notes call for, such as the hook block, slings, shackles, a spreader or lifting beam, jib position and load-line weight. A jib deduction is a chart allowance and need not equal its physical weight. Do not count a rigging total together with its parts, and do not subtract an item the starting value already excludes.
Does a correct subtraction mean the lift is within capacity?
No. The worksheet is arithmetic for study and checking. It cannot confirm that you picked the right chart cell, that the load weight is right, or that the setup matches the chart. Your crane's chart, the lift plan and your qualified person govern a real lift, and the invented practice charts are never for lifting operations.
Not sure what the load itself weighs? The load weight calculator estimates it from shape and material, and lets you add the rigging weight.
Want the same lift as one number? The crane percent of capacity calculator adds the load and deductions into a total and shows the percent of chart capacity, with flags at marks you choose.