MasaApps360
English
RigMaster

Sling angle factor chart and what the multiplier means

The sling angle factor is 1 ÷ sin of the horizontal sling angle: 1.000 at 90°, 1.155 at 60°, 1.414 at 45° and 2.000 at 30°. Multiply each leg's share of the load by it to get the leg tension. RigMaster's free Angle Reference screen shows the full table and curve.

3 min read · Updated 2026-09-16

Download on the App Store

What is sling angle factor?

It's the number that tells you how much extra tension a sling leg takes on because it isn't hanging straight down. A factor of 1.155 means the leg sees 15.5% more than its vertical share of the load.

The factor depends only on the angle, not the weight or the sling type. One chart covers every pick, which is the whole point of printing it once.

Sling angle factor formula

Factor = 1 ÷ sin(θ), with θ measured from the horizontal. Because sin θ is the vertical height divided by the sling length, the factor is also sling length ÷ height. A 10 ft sling that hangs 8 ft vertically has a factor of 10 ÷ 8 = 1.250.

Sling angle factor chart

Tension multiplier by horizontal sling angle, as listed in RigMaster's Angle Reference
Horizontal angleFactorTension on each of 2 legs, 2,000 lb loadBand
90°1.0001,000 lbOK
85°1.0041,004 lbOK
80°1.0151,015 lbOK
75°1.0351,035 lbOK
70°1.0641,064 lbOK
65°1.1031,103 lbOK
60°1.1551,155 lbOK
55°1.2211,221 lbOK
50°1.3051,305 lbOK
45°1.4141,414 lbOK
40°1.5561,556 lbcaution
35°1.7431,743 lbcaution
30°2.0002,000 lbcaution, the limit

Read down the table and the factor barely moves from 90° to 60°, then climbs quickly. Between 45° and 30° it rises by more than it did in the whole range from 90° to 45°.

Sling angle factor at 60 degrees

At 60° the factor is 1.155. It is a common target on site because the extra tension is modest and the legs do not need to be very long. At 45° you are at 1.414, and many riggers treat that as the point to start paying close attention.

Multiplier vs. load angle factor: two charts, one idea

Some charts list a load angle factor of sin θ instead: 0.866 at 60°, 0.707 at 45°, 0.500 at 30°. That version reduces the sling's capacity, where the multiplier increases the tension. They are reciprocals and give the same answer; just make sure you multiply with the right one. RigMaster uses the multiplier, 1 ÷ sin θ, everywhere.

Look it up in RigMaster

  1. Open Angle Reference from the Calculators list.
  2. Follow the curve: it turns yellow below 45°, with dashed lines at 45° and 30°.
  3. Scroll to Tension Multiplier by Sling Angle for the 5° table from 90° to 30°.
  4. For an angle between the steps, open Sling Tension, set the exact Horizontal Angle and read the Angle Factor with three decimals.

Angle Reference has no inputs, so there is nothing to save there. It works offline like the rest of the app.

Why low angles are dangerous

  • Below 45°, small angle errors cause big tension errors. Misjudging 35° as 40° understates the factor by about 0.19.
  • Below 30°, the pick is not permitted by standard rigging practice. RigMaster still shows the number under a red placard so you can see why.
  • Low angles also squeeze the load sideways, which can crush or tip it, something no factor chart shows.

Questions and answers

How do you calculate sling angle factor?
Divide 1 by the sine of the horizontal angle, or divide the sling length by the vertical height. For 45°, 1 ÷ 0.7071 = 1.414.
What is the sling angle factor at 30 degrees?
2.000. Each leg of a 2-leg sling then carries the full weight of the load, which is why 30° is the usual lower limit.
Is there a free sling angle chart app?
RigMaster's Angle Reference chart is free and works offline on iPhone and iPad, with the 13 factors from 90° to 30° and a curve.
Why does my chart show 0.707 at 45 degrees?
That chart lists sin θ, a capacity reduction factor. It is the reciprocal of the 1.414 multiplier, so both lead to the same safe load.

You might also like

More RigMaster guides