Will the slings hold? Sling & rigging calculator

Chain, wire rope, webbing or roundsling: pick the sling, the number of legs and the angle — the calculator checks the load and shows the force in every leg.

Example A ready example: the inputs are locked. Your own check and the force in every leg come with Hobby; asymmetric lifts, centre of gravity, formulas and the lifting plan come with Pro.

Hobby The check runs on the server: every “Check” uses 1 of your monthly calculations (shared with 1D and 2D cutting). Asymmetric lifts, centre of gravity, formulas and the lifting plan come with Pro.

Inputs

Example

Inputs

1Load

Load weight

Work out the weight in the weight calculator →

Rigging below the hook

shackles, spreader, the slings themselves — added to the load

Origin of the weightThe crane is not a scale: a weight read off the crane’s load indicator is “estimated” (WSH). The reserve is added to the load before every check.

Reserve on the weight

2Sling

Chain diameter

Textile materiallabel colour: blue PES, green PA, brown PP

3How the load is slung

Number of legs

Hitch

Angle β from the vertical

β is the angle between the leg and the vertical through the hook. The angle between two legs is 2β.

The centre of gravity is off-centre / the legs differ in length Pro

Asymmetric 2-leg lift — the force in each leg separately — with Pro.

Rules of use

The sling is marked for angles up to 60° Check the tag: a marked sling also shows a WLL for 45–60°. Without the marking — up to 90° between the legs (β ≤ 45°).

4Conditions and accessories

Sling temperature

Shackle on each leg (as marked)

Connection to the hook

Hook WLL (as marked)

Master link WLL (as marked)

Empty = not checked. Directly in the hook: at most 2 legs and only with an angle between them up to 90° (β ≤ 45°); more legs or a wider angle — through a master link or a bolt type shackle (Crosby, ASME B30.10). Do not overcrowd the hook — join the upper ends of the legs in a shackle or link (LEEA COPSULE 14.5.2.6, note). The sling passes over sharp edges of the load

Shock during the lifte.g. a slack sling snatched tight, or a load that slips

Lift diagram

Will it hold?

Example

chain grade 8 ⌀10 mm · 2 legs · straight Weight 3000 kg, calculated + 5 % = 3150 kg · + rigging 50 kg = 3200 kg Rules of use: Europe / UK (EN + LEEA)

YES, 76 % utilisation

Governs: the sling WLL (mode factor method)

The force in each leg — with Hobby.

Load the shackle in line. At a side angle (bolt or screw pin shackles, Crosby): up to 10° — 100 %, 11–20° — 85 %, 21–30° — 75 %, 31–45° — 70 %, 46–55° — 60 %, 56–70° — 55 %, 71–90° — 50 %. Never side-load a round pin shackle.

The hook carries the whole load W (with rigging and reserve). The master link must sit freely in the bowl of the hook and the latch must not carry load (Crosby). Check that the hook takes the sling’s master link by size.

Your own check comes with Hobby or Pro.

Valid for slings with a legible tag, in good working order and with a valid periodic inspection. It does not replace the check before lifting.

Scope and limits

The calculation assumes that the slings, shackles and hook are in good working order: legibly marked, free of unacceptable wear, deformation, cracks, cuts or corrosion, and with a valid periodic inspection. The check before every lift, maintenance, inspections and discard are the responsibility of the owner and user of the slings and of the competent slinger, under the applicable rules. The result is an aid and does not replace the judgement of the person in charge.
The mode factor method (EN 818-4, EN 13414-1, EN 1492-1/-2) applies to symmetric loading: load under 80 % of the WLL, legs at least 15° from the vertical, leg angles within 15°. Otherwise the sling is rated with one leg less.
Rules of use “Europe / UK”: β up to 60° from the vertical (angle between the legs up to 120°) with the EN 45–60° factors (EN 818-6, EN 13414-1, EN 1492, LEEA COPSULE). The rules of use are national — check yours (the list is in the lifting plan).
Catalogue values are for one leg in a straight pull. For a 2–4 leg chain sling the lower of M · WLL₁ and the EN 818-4 table is used (grade 10: the manufacturer’s table). The marking (tag, label) of your sling governs.
The hook and the master link are checked only by WLL (against the whole load with rigging and reserve) and by the number of legs in the hook (at most 2, angle up to 90°). Not checked: eyebolts, lugs on the load and spreader beams — check them separately.
Shock: medium — the sling, shackle and hook WLL × 0.7, heavy — not allowed (pewag, LINX-8). Wind and a jerky crane start are not included — lift smoothly.
The reserve on the weight follows its origin: calculated 5 %, weighed 3 %, estimated 25 % (defaults, can be changed). The crane is not a scale — a weight from the crane’s load indicator is “estimated” (WSH).
The result is an aid. The person in charge of the lift is responsible for it.

Pro: asymmetric lifts and unequal legs, centre of gravity of an assembly, 4 points on a rigid load, step-by-step formulas, a printable “Lifting plan” and saved calculations.Unlock with Pro

Step-by-step calculation

Pro

Mode factor, sling WLL, leg force and utilisation — with the formulas and the numbers.

Unlock with Pro

Centre of gravity

Pro

A list of parts (weight and coordinates) → total weight and centre of gravity; the forces at 2 and 4 lifting points.

Unlock with Pro

Lifting plan

Pro

A printable document: inputs, diagram, leg forces, formulas, warnings, standards and signature lines.

Unlock with Pro

Saved calculations

Pro

Save your calculations and open them again.

Unlock with Pro

How the calculator checks the slings

Enter the weight of the load, the sling (grade 8 or 10 chain, wire rope, webbing sling or roundsling), the number of legs, the hitch and the angle β from the vertical, or the leg length and the distance between the lifting points. A reserve is added to the weight by its origin (calculated, weighed or estimated), and so is the rigging below the hook.

The result is YES or NO with the utilisation. The strictest of four checks governs: the sling WLL by the mode factor method, the most loaded leg, the shackle and the hook or master link. Temperature, sharp edges, shock and the symmetry of the lift are taken into account.

The larger the angle, the larger the force in the legs: with two legs at 45° each leg carries about 71 % of the weight, and at 60° the whole weight. Above 60° from the vertical the lift is not allowed.

Rules of use: Europe / UK and Bulgaria

The EN standards for slings are common across Europe, but the rules of use are national. Under “Europe / UK” β goes up to 60° with the EN factors for 45–60° (LEEA COPSULE). Under “Bulgaria” the angle between the legs is limited to 90° (β ≤ 45°) by art. 69 of the Bulgarian regulation on lifting equipment; a larger angle only with a sling marked for it.

In Great Britain a lifting operation is planned by a competent person under LOLER 1998 (reg. 8). The lifting plan (Pro) switches the roles and signature lines with the chosen rules: LOLER and BS 7121-1 for Europe / UK, the Bulgarian regulation for Bulgaria.

Frequently asked questions

What is the working load limit (WLL) of a sling?

It is the load on the sling’s tag for one leg in a straight lift. The WLL of the whole sling depends on the number of legs, the angle and the hitch: a choke takes 20 % off, a basket with parallel legs doubles it. The list shows the catalogue WLL next to each size; the tag on your sling governs.

Why does the angle between the legs matter so much?

The force in every leg grows with the angle. That is why a two-leg sling carries 1.4 times one leg only up to 45° from the vertical, and from 45° to 60° just as much as one leg. Above 60° the lift is not allowed; under the Bulgarian rules above 45° only with a sling marked for it.

Which standards are the tables based on?

Grade 8 chain: EN 818-4; grade 10 chain: the makers’ tables (it is not in EN 818); wire rope: EN 13414-1; webbing slings and roundslings: EN 1492-1 and EN 1492-2 with the colour code; shackles: the EN 13889 series. Use: EN 818-6, EN 13414-2 and LEEA COPSULE.

Does the calculator replace the check of the slings?

No. The result is an aid and holds for slings with a legible tag, in good working order and with a valid periodic inspection. The check before every lift, the inspections and discard remain the duty of the owner and user of the slings and of the slinger.

Is the sling calculator free?

Without an account and on the free plan you see a ready example. With Hobby you check your own slings: every check uses 1 of 30 calculations a month, shared with 1D and 2D cutting. Pro and Lifetime add asymmetric two-leg lifts, the centre of gravity, step-by-step formulas, a printable lifting plan and saved calculations.