Choosing the Correct Lifting Sling
Knowing how to choose a lifting sling comes down to a few questions: how much the load weighs and where its center of gravity is, how you will rig it, what angle the legs will make, and what the sling will be exposed to. This guide walks through each step and compares the five most common sling types, chain, nylon web, polyester web, polyester round and wire rope, so you can match the sling to the lift.
Safety first: Never exceed the rated load shown on the sling tag for the hitch and angle you are using. This guide is a summary; always follow the sling manufacturer’s instructions and the current OSHA 1910.184 and ASME B30.9 requirements.
Quick Comparison of Sling Types
Each sling material has strengths and trade-offs. Use this table to narrow the field, then work through the steps below. Rated capacities vary by size and construction, so check the tag or our capacity charts for exact figures.
Sling type comparisonGeneral characteristics; the manufacturer’s tag and instructions govern.
| Property | Grade 100 chain | Nylon web | Polyester web | Polyester round | Wire rope |
|---|---|---|---|---|---|
| Strength-to-weight | Lowest; heaviest to handle | High; light and easy to rig | High; light and easy to rig | Highest; very light for its rating | Moderate; heavier than synthetics |
| Abrasion & cut resistance | Excellent; most durable | Low; needs wear pads and edge protection | Low; needs wear pads and edge protection | Low; cover protects the core but cuts easily | Good abrasion resistance; can be crushed or kinked |
| Heat | Best of the five; most manufacturers rate it at full capacity up to 400°F, with reductions above that | OSHA limits nylon and polyester web slings to 180°F | OSHA limits nylon and polyester web slings to 180°F | Follow the manufacturer’s temperature limit | Fiber core: OSHA limit 200°F. Steel core (IWRC): up to 400°F; above 400°F per the manufacturer |
| Chemicals | Avoid acids and caustics; ask the manufacturer | Not where acid or phenolic fumes or vapors are present (OSHA) | Not where caustic fumes or vapors are present (OSHA) | Polyester fiber: same as polyester web; check the manufacturer | Corrodes; avoid acids and caustics; ask the manufacturer |
| Stretch | Very little | Most stretch of the five | Less than nylon | Low | Low |
| Load-surface protection | Poor; can mar finished surfaces | Excellent; soft and wide | Excellent; soft and wide | Excellent; conforms to the load | Fair; can mark finished surfaces |
| Design factor | 4:1 | 5:1 | 5:1 | 5:1 | 5:1 |
| Typical uses | Steel, foundries, hot or rough loads, adjustable bridles | General lifting, finished or delicate loads | Finished loads, low-stretch placement, acid environments | Machinery, pipe, irregular shapes, chokers | Construction, steel erection, abrasive loads |
Swipe the table sideways to see all five sling types.
How to Choose a Lifting Sling, Step by Step
1. Know the load weight and center of gravity
Start with the actual weight of the load, from a scale, shipping papers or the manufacturer’s data, not a guess. Include any rigging hardware below the sling. Then find the center of gravity: the hook must be directly above it, or the load will tilt or swing when it leaves the ground. On an off-center load, the legs closest to the center of gravity carry more of the weight.
Design factor: wire rope and synthetic slings use a 5:1 design factor and alloy chain slings use 4:1, meaning the minimum breaking strength is four or five times the working load limit. That margin is built in for wear and dynamic forces; never treat it as extra capacity.
2. Choose the hitch (single-leg slings)
For a single-leg sling, the vertical rating on the tag is its full rated capacity. The hitch you rig changes that, and the tag or chart lists a rated load for each hitch the sling is approved for.
- Vertical: one end on the hook and one on the load. Uses the full vertical rating with no reduction, but gives little control, so use a tagline and do not use it on loose or long loads.
- Choker: the sling wraps around the load and passes through its own eye, gripping as it tightens. A choker reduces capacity by 20% for nylon and polyester web, polyester round and Grade 100 chain slings, and by 25% for wire rope. Use the choker value on the tag or chart. ASME B30.9 requires a further reduction when the angle of choke is less than 120°. The choke point should sit on the sling body, never on a fitting, splice or tag.
- Basket: the sling cradles the load with both ends on the hook. With both legs vertical, a basket is rated at twice the vertical rating. When the basket legs are angled, that capacity is reduced by the same sling-angle effect described in step 4. Keep the load balanced so it cannot tip out.
Single-leg sling: capacity by hitchCompared with the tag’s vertical rating
| Hitch and sling type | Capacity |
|---|---|
| VerticalAll sling types | No reduction |
| ChokerNylon & polyester web, polyester round, Grade 100 chain | 20% reduction |
| ChokerWire rope | 25% reduction |
| Basket (legs vertical)All sling types | 2× vertical rating |
Choker capacity = Vertical rating − (Vertical rating × reduction)
Reduction: enter .20 for nylon, polyester, round or chain (20%). Enter .25 for wire rope (25%).
Example only, not a rating:
- 10,000 − (10,000 × .20) = 8,000 lb in a choker
- Wire rope: 4,000 − (4,000 × .25) = 3,000 lb in a choker
A choke angle under 120° reduces capacity further, and the rating on the sling tag always governs.
D/d ratio (bend tightness): in a basket hitch or over a pin or hook, D/d is the diameter of the surface the sling bends around (D) divided by the sling diameter (d). A tight bend reduces capacity. For example, a 1/2″ wire rope sling bent around a 10″ pipe has a D/d of 20:1 (10 ÷ 0.5 = 20). Standard wire rope basket ratings assume a D/d of roughly 25:1 or greater, and chain or synthetic slings bent over small pins or sharp corners also lose capacity; follow the manufacturer’s D/d chart.
3. Decide how many legs
A single-leg sling suits loads with one lifting point. Two-, three- and four-leg bridle slings spread the load across several pick points and give better control. On a rigid load, legs of a multi-leg sling rarely share the weight equally, so many riggers rate three- and four-leg bridles as if only two legs carry the load. Follow the tag and a qualified person’s judgment.
4. Account for the sling angle (multi-leg bridles)
Two-, three- and four-leg bridle slings are rated differently from single-leg slings: the tag or chart rating is already given at a 60° sling angle, measured from the horizontal. So at 60° you get 100% of the rated capacity. Our chain sling and wire rope sling capacity charts list 2-, 3- and 4-leg bridle ratings at 60°, 45° and 30°.
If the legs are flatter than 60°, each leg pulls harder and the capacity drops below the 60° rating. Use the chart’s 45° or 30° column, or choose a larger sling. ASME B30.9 does not allow horizontal sling angles below 30° unless approved by the sling manufacturer or a qualified person. If the legs are steeper than 60°, still use the tag rating unless the manufacturer’s chart lists higher-angle values.
Multi-leg bridle: reduction from the 60° tag ratingAngle measured from horizontal
| Sling angle | Reduction | Relative |
|---|---|---|
| 60° (tag rating) | No reduction (100%) | |
| 45° | Reduced by 18% | |
| 30° | Reduced by 42% | |
| Below 30° | Not recommended | — |
Example only, not a rating: a 2-leg bridle tagged 10,000 lb at 60° is good for about 8,200 lb at 45° and about 5,800 lb at 30°. Always use the values on your sling’s tag or chart.
When the angle is too flat: if wide pick points or low headroom would push the sling angle below 30° (or cut too much capacity), use a spreader beam or lifting beam so the slings hang vertically or at a steeper angle.
5. Check the environment
- Heat: OSHA 1910.184 does not allow nylon or polyester web slings above 180°F. For wire rope slings, fiber core must be removed from service after exposure above 200°F, and steel core (IWRC) may be used up to 400°F (above 400°F, follow the manufacturer). Alloy chain handles the most heat: most Grade 100 manufacturers rate it at full capacity up to 400°F and reduce the rating above that, so use the manufacturer’s chart; OSHA requires permanent removal of alloy chain heated above 1000°F.
- Chemicals: OSHA 1910.184 says nylon web slings are not to be used where acid or phenolic fumes or vapors are present, and polyester web slings are not to be used where caustic fumes or vapors are present. Chain and wire rope can corrode. For any chemical exposure, check with the sling manufacturer.
- Edges and abrasion: rough surfaces and sharp corners wear synthetics quickly. Use chain or wire rope, or protect synthetic slings (see edge protection below).
- Finished surfaces: nylon, polyester web and round slings are the least likely to scratch or crush a load.
6. Get the right length and reach
Length controls the sling angle. A sling that is too short forces a flatter angle and lowers the capacity; a sling that is too long can use up your headroom or let the load swing. Measure the distance between pick points and the available hook height before you order. Chain and wire rope reach is measured from bearing point to bearing point, as shown on the tag.
7. Match the fittings
Every hook, link and shackle in the rigging must be rated at least as high as the load it carries. Sling eyes should seat in the hook without being pinched or bunched; when they do not fit, connect with a shackle. Choose sling hooks, grab hooks for adjustable chain legs, or a master link sized for your crane hook, and check our shackle capacity chart when sizing shackles.
Our Custom Sling Builder covers nylon, chain, wire rope and round slings. Or browse chain slings, nylon slings, round slings, wire rope slings and shackles.
Edge Protection
A synthetic sling pulled tight over a sharp corner can be cut without warning, even well below its rated load. ASME B30.9 requires slings to be protected from sharp edges, protrusions and abrasive surfaces.
- Place pads, sleeves or corner protectors between the sling and any sharp edge, and make sure they stay in place as the load lifts.
- A wear sleeve is not cut protection unless the manufacturer rates it that way.
Pick a Sling by Situation
Quick guideA starting point only; confirm the rating for your hitch and angle.
| If you have… | Consider |
|---|---|
| Painted, polished or delicate load | Nylon or polyester web, or a round sling, with edge protection |
| Hot work, or temperatures above 180°F | Grade 100 alloy chain, within the manufacturer’s temperature chart |
| Sharp edges or rough castings | Chain, or a synthetic sling with suitable edge protection |
| Acid fumes or vapors | Polyester (not nylon); confirm with the manufacturer |
| Caustic (alkaline) fumes or vapors | Nylon (not polyester); confirm with the manufacturer |
| Precise placement, little stretch | Polyester web or round sling, chain or wire rope |
| Round or irregular loads in a choker | Polyester round sling |
| Repeated, heavy, rough service | Grade 100 chain |
| Legs that must be adjusted | Multi-leg chain sling with grab hooks |
| Construction and general rigging | Wire rope sling |
When to Retire a Sling
Inspect every sling before each use. Take it out of service immediately if you find any of these removal conditions:
Remove from service if you see…
| Sling type | Retire the sling if you find |
|---|---|
| All slings | Missing or illegible identification tag, knots in any part of the sling, or cracked, bent, twisted or worn hooks and fittings (including a hook opened more than 15% or twisted more than 10°). |
| Synthetic web (inspection guide) | Acid or caustic burns, melting or charring, holes, tears, cuts, snags, broken load-bearing stitching, excessive abrasive wear, or red warning yarns showing. |
| Polyester round (inspection guide) | Any cut, hole, tear, snag, burn, heat damage or weld splatter that exposes the core yarns, or broken or lumped core yarns felt through the cover. |
| Wire rope (inspection guide) | 10 randomly distributed broken wires in one rope lay or 5 broken wires in one strand in one rope lay (strand-laid slings), kinking, crushing, birdcaging, heat damage, or corrosion. |
| Grade 100 chain (inspection guide) | Cracks or breaks, stretched links, links that do not hinge freely, excessive wear, nicks or gouges, weld splatter, or heat damage (including exposure above 1000°F). |
Frequently Asked Questions
What is the most important factor when choosing a lifting sling?
The rated load for the way you will use it. Start with the actual load weight, then make sure the sling’s rated capacity for your hitch (single-leg slings) or sling angle (multi-leg bridles) is at or above that weight. The tag shows the rated loads.
Should I use a nylon or polyester sling?
Both are light and protect finished surfaces. Nylon stretches more than polyester and is not to be used where acid fumes are present; polyester stretches less and is not to be used where caustic fumes are present. Choose polyester for low-stretch, precise placement.
When should I use a chain sling instead of a synthetic sling?
Use Grade 100 alloy chain for hot work, rough or abrasive loads, sharp edges and heavy repeated service, or when you need adjustable legs. Chain is heavier and can mark finished surfaces.
How does sling angle affect the capacity of a multi-leg sling?
Two-, three- and four-leg bridle ratings are given at a 60° sling angle measured from the horizontal, so 60° is 100% of the rated capacity. Flatter angles reduce it: by about 18% at 45° and about 42% at 30°. ASME B30.9 does not allow angles below 30° without approval from the manufacturer or a qualified person.
How do hitches change the capacity of a single-leg sling?
The vertical rating on the tag is the full rating, with no reduction. A choker hitch reduces capacity by 20% for nylon and polyester web, polyester round and Grade 100 chain slings, and by 25% for wire rope. Use the choker rating on the tag or chart. It drops further when the angle of choke is less than 120°. A basket hitch with both legs vertical is rated at twice the vertical rating; angled basket legs reduce that.
Sources: OSHA 29 CFR 1910.184, Slings; ASME B30.9, Slings; WSTDA WS-1 (synthetic web slings) and RS-1 (polyester round slings) recommended standards; sling manufacturers’ instructions. This guide summarizes those requirements and does not replace them.