Lifting Lug Capacity Calculator
Estimate the tension capacity of a padeye or lifting lug at its net section through the pin hole, using plate thickness, lug width, hole diameter, steel yield strength and a safety factor. This is a first-pass sizing check only, not a full padeye design.
Enter Values
Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Enter the plate thickness t, lug width W and pin hole diameter, all in millimetres.
- Optionally override the steel yield strength (default 250 MPa) and safety factor (default 3); leave blank to use the defaults.
- Read the net section area, allowable tensile stress and the resulting lug tension capacity in kN.
How it works
The net width at the hole is W minus the hole diameter. The net section area is that width times the plate thickness. The allowable tensile stress is the yield strength divided by the safety factor, and the tension capacity is allowable stress times net area, divided by 1000 to convert N to kN. The hole diameter must be smaller than the lug width or there is no net section to carry load.
Worked example
Worked example. A 20 mm plate, 100 mm wide, with a 40 mm hole, fy = 250 MPa and SF = 3: net width = 100 - 40 = 60 mm, net area = 20 x 60 = 1200 mm2, allowable = 250 / 3 = 83.33 MPa, so P = 83.33 x 1200 / 1000 = 100 kN.
Common mistakes
- Treating this net-section value as the full lug capacity — bearing, pin shear, weld and out-of-plane checks usually govern.
- Ignoring the sling angle, which increases the load in each lug well above the vertical share.
- Using an unrealistically low safety factor; lifting standards typically require generous factors and design by a competent person.
Frequently asked questions
Does this replace a proper padeye design?
No. It only checks tension across the net section at the pin hole. A compliant design must also address bearing, pin shear, welds, cheek plates and out-of-plane loading, and be certified by a competent person per the lifting code.
What safety factor should I use?
Lifting codes commonly require a factor of 3 or more on yield, and higher on ultimate. The default of 3 is a conservative starting point — always follow the governing standard for your jurisdiction and duty.
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Tip: Enter any known values to calculate the remaining results.
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