Chain Sling Calculator
Estimate alloy chain sling capacity from grade, chain size, load-carrying legs, sling angle, hitch type, temperature derate, edge or D/d derate, load weight, component limits, and safety factor.
⚙Real Chain Sling Presets
📏Chain Sling Inputs
⛓Chain Grade / Spec Grid
📊Single-Leg Vertical WLL Reference
| Chain size | Metric size | Grade 80 vertical WLL | Grade 100 vertical WLL |
|---|---|---|---|
| 9/32 in | 7 mm | 3,500 lb | 4,300 lb |
| 5/16 in | 8 mm | 4,500 lb | 5,700 lb |
| 3/8 in | 10 mm | 7,100 lb | 8,800 lb |
| 1/2 in | 13 mm | 12,000 lb | 15,000 lb |
| 5/8 in | 16 mm | 18,100 lb | 22,600 lb |
| 3/4 in | 20 mm | 28,300 lb | 35,300 lb |
| 7/8 in | 22 mm | 34,200 lb | 42,700 lb |
| 1 in | 26 mm | 47,700 lb | 59,700 lb |
| 1-1/4 in | 32 mm | 72,300 lb | 90,400 lb |
📐Sling Angle and Leg Reference
| Angle from horizontal | sin(angle) factor | Tension factor | Planning note |
|---|---|---|---|
| 90° | 1.000 | 1.00 times load share | Vertical leg, best geometry |
| 75° | 0.966 | 1.04 times load share | Very good bridle angle |
| 60° | 0.866 | 1.15 times load share | Common preferred minimum |
| 45° | 0.707 | 1.41 times load share | Capacity drops quickly |
| 30° | 0.500 | 2.00 times load share | Generally avoid without qualified lift planning |
🔥Temperature Derating Reference
| Maximum chain temperature | G80 while hot | G100 while hot | Action |
|---|---|---|---|
| Below 400°F | 1.00 | 1.00 | Normal WLL range down to -40°F |
| 400°F | 0.90 | 0.85 | Apply heat reduction |
| 500°F | 0.85 | 0.75 | Check manufacturer chart |
| 600°F | 0.80 | 0.70 | Also consider permanent reduction |
| 700°F | 0.70 | 0.60 | Severe service; inspect before reuse |
| 800°F | 0.60 | 0.50 | Qualified approval needed |
| 900°F | 0.50 | 0.40 | Very limited remaining capacity |
| 1000°F | 0.40 | 0.30 | Maximum listed temperature |
| Over 1000°F | Remove | Remove | Remove sling from service |
🛡Hitch, Edge, and Formula Reference
| Item | Factor / formula | Where used | Important limit |
|---|---|---|---|
| Rated capacity | WLL x legs x sin(angle) x hitch x heat x edge | Before safety factor | Never above tag or lowest component |
| Adjusted capacity | Rated capacity / safety factor | Main pass/fail card | Safety factor is extra reserve over WLL |
| Required leg WLL | Load x safety factor / all factors | Minimum chain leg rating | Round up to an actual tagged assembly |
| Vertical / bridle | 1.00 | Straight legs | Angle factor still applies |
| Choker hitch | 0.80 x choke angle factor | Chain choker estimate | Use tag if choker WLL is marked |
| Basket hitch | 2.00 before angle and derates | Both sides support load | Uneven contact can reduce capacity |
| Four-leg bridle | Usually count 3 effective legs | Default leg rule | Use all 4 only if equalized and verified |
| Sharp edge / D/d | 1.00 to 0.50 | Contact derating | Protect edges; redesign severe contact |
💡Chain Sling Calculation Tips
A chain sling calculator are used to determine the actual capacity of a chain sling under specific conditions. Many people know the working load limit of a chain sling, but that working load limit change with the angle of the lift, the temperature of the environment in which the chain sling is used, and how the load may affect the chain sling. Since the working load limit is based upon ideal conditions, the use of a chain sling calculator to determine the actual capacity of the chain sling under these other conditions are essential.
To use the calculator, there are several specific variables that must be entered. The grade and size of the chain sling will provide the initial working load limit for the chain sling. However, the other variables will reduce the initial working load limit of the chain sling.
How to Find the Real Capacity of a Chain Sling
If the load is being lifted with a two leg bridle at a sixty degree angle, the tension in each of those leg will be higher than the weight of the load. The calculator will use the sine of the angle to calculate this value, saving the user from have to manually calculate the sine of the angle. Additionally, the hitch that the user uses can affect the capacity of the chain sling.
A choker hitch, for example, does not have the same capacity as a vertical leg hitch. The choke angle for a choker can be entered into the calculator to determine how this may impact the capacity of the chain sling. The temperature at which the chain sling is used can impact the capacity of that chain sling.
An alloy chain sling will lose strength as the temperature increase. To account for this, the temperature derate can be entered into the calculator to reflect the impact of the temperature on the capacity of the chain sling. Additionally, if the load has any sharp edge or tight bends, the calculator will reduce the capacity of the chain sling to account for the effect of those sharp edges.
The d/D or edge derate function within the calculator will account for the impact of these sharp edges on the chain sling. When the calculator is run, the actual capacity of the chain sling will be shown. The adjusted capacity will take into account all derate factors entered into the calculator, and will include the safety factor that the user selected when using the calculator.
The required WLL per leg will tell the user what size of chain sling would of been required if the current chain sling cant meet the requirements of the load. The tension of the load will be calculate for the user. Additionally, if the chain sling is found to be over it’s capacity, the status line within the calculator will tell the user the specific reasons that the chain sling is over its capacity.
Four leg bridles require special consideration when determining the working load limit of the chain sling. Many people believe that the weight is distribute equally to each of the four legs of a four leg bridle. However, in many cases, one of the four legs of the bridle may be slack, indicating that the remaining three legs are bearing the full weight of the load.
Using the four leg bridle option in the calculator will treat the four leg bridle as if it were a three leg bridle rather than a four leg bridle. This is the standard practice in the industry in relation to four leg bridles. An alternative option allows the user to enter the load as an unequal load bridle if the load is off center relative to the four leg bridle.
The hardware that the user will use during the lift also should be considered when calculating the capacity of the lift. Master links, hooks, and shortening clutches are three of the hardware components of a chain sling. These components are often the weakest part of the sling.
By entering the strength of the weakest piece of hardware into the calculator, the capacity of the lift will reflect the capacity of the weakest part of the chain sling assembly. This will ensure that the user does not make the mistake of using a hardware component that is under the strength of the chain sling itself. By using a chain sling calculator before beginning the lift, the rigger can determine if there are any problem with the rigging prior to lifting the load with the crane.
If problems are found, they can be corrected before the lift begins. Using the calculator will save the rigger from having to manually calculate the mathematics of the lift. Additionally, it will allow the rigger to ensure that the chain sling will match the actual conditions of the lift.
