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Crane Lift Calculator

Lift check sheet · ajmalps.com/toolbox/crane-lift-calculator/

Sling tension, ground bearing pressure and pad size, permissible wind speed, required boom length and headroom. Everything runs on your own device. Nothing is uploaded, nothing is stored, and it keeps working with no signal on site.

Read this before you use the numbers. This is an aid to checking, not a lift plan. It does not replace the crane manufacturer's load chart, a competent Appointed Person, or your site lifting risk assessment. Three things are deliberately simplified and you must allow for them yourself: outrigger force ignores working radius (a 5 m and a 20 m lift give the same figure here, but the real reaction rises sharply with radius); no shock or dynamic factor is applied; and the centre of gravity is assumed central. Confirm every figure against the crane OEM chart and your sling certificates before lifting.

Lift Data

T
T
T
T

Read from the crane load chart at your working radius and boom length.

Total lift weight
0.00 T
Crane utilisation
--

Ground Pressure

T
T

Share of the machine weight carried by the worst outrigger. A working estimate only.

T/m²
m
Max outrigger force
0.00 T
Required pad area
0.00 m²
Min pad size
0.000 m
Suggested pad size
0.00 m
Actual pad area
0.00 m²
Actual ground pressure
0.00 T/m²

This does not account for working radius. The load is added at 100%, so the same lift at 5 m and at 20 m gives the same figure here. Take the real reaction from the crane OEM outrigger load chart before setting pads. GBP must be the allowable bearing pressure, already factored, not the ultimate. Pad is assumed square.

Sling & Rigging

Legs assumed to carry: 2

T
m
°

 

m
m
m
Load on slings (load + gears)
0.00 T
Tension per leg
0.00 T
Sling utilisation
--
Status
—

Only 2 legs are assumed to carry the load, whatever number is fitted. This follows BS 7121 site practice. EN 13414 allows at most 3 on a rigid load with equalised legs. Never assume all 4 share. Below 30° from horizontal the check fails, because tension climbs steeply. Keep 45° to 60° or better. The hook block is excluded here because it hangs above the slings. Hitch percentages are guidelines, so confirm the rated capacity from your sling's tag or certificate.

Wind Speed

m/s
m²

Suggested sail area: 0.00 m² — the larger face, length or width by height, worst case.

m²/T

A fixed constant: the sail area per tonne the crane's load chart already assumes. This is not air density. Locked on purpose.

Load mass used (no hook block)
0.00 T
Sail area used
0.00 m²
Calculated from sail area
0.00 m/s
Max permissible wind
0.00 m/s

 

A simplified estimate. The result is capped at your V chart value, because the chart wind speed is the crane's structural limit and a compact load does not raise it. Always cross-check the manufacturer's chart before lifting.

Boom Geometry

m
m
m

Pivot height is the boom foot above ground, usually 1.5 m to 2.5 m on a truck crane. Check your machine.

Boom tip height needed
0.00 m
Rise above pivot
0.00 m
Required boom length
0.00 m
Required boom angle
0.00 °

The boom tip must clear the load, not just the building. This includes the full rigging stack from the Headroom card, so the length here is longer than target height alone would give. Use the working radius to pick chart capacity. Maximum boom length and angle are fixed by the manufacturer chart, so check this sits inside your crane's range. Radius is taken from the slew centre and the pivot's horizontal offset behind it is ignored, which errs in your favour.

Headroom Check

Target height comes from Boom Geometry. Load height, sling length and sling angle come from Sling & Rigging.

m
m
Sling vertical drop
0.00 m
Rigging stack (hook + sling + load)
0.00 m
Plus clearance margin
0.00 m
Boom tip height needed
0.00 m

This is the boom tip height needed above ground to place the load at target height, and it is the same number Boom Geometry uses. Check it against your crane's real maximum tip height on the load chart at this radius. The tool does not know your crane's actual reach.

Diagrams

Ground pressure
Force: 0.00 T 0.00 x 0.00 m —
Sling & rigging
— 60° Tension: 0.00 T/leg
Wind speed
Max: 0.00 m/s Permissible wind on this load Check crane chart wind limit too
Headroom check
Rig stack: 0.0m Target: 0.0m Total: 0.0m
Lift overview
R: 0.0m 0° 0.0m H: 0.0m

What this follows. Sling load sharing uses the BS 7121 site rule of two legs. Sling angle is measured from the horizontal, so tension per leg is the suspended weight divided by the legs sharing and by the sine of that angle. Wind uses the standard chart formula with a fixed 1.2 m²/T reference ratio, capped at the chart wind speed. Ground pressure is force divided by a square pad area. Boom geometry is a right triangle from the boom pivot to the required tip height.

Built by Ajmal P.S, MEP BIM Coordinator in Doha, Qatar. Found something wrong, or want a check added? Tell me and I will fix it.

Produced with the free crane lift calculator at ajmalps.com/toolbox/crane-lift-calculator/ · Aid to checking only. Not a lift plan, and no substitute for the crane manufacturer's load chart, a competent Appointed Person, or the site lifting risk assessment.

Prepared  ____________________   Checked  ____________________   Approved (Appointed Person)  ____________________   Date  ____________