Designed to help guide doggers and riggers understand and visualise angle factors and their relative sling tensions for safe lifting. The calculator includes variables such as: included angle (θ between sling legs), load weight,
sling tension per leg, 2/3/4‑legged sling configurations, plus
a quick sanity check and option to print results.
θ = included angleSymmetric defaultEducation tool
10,000kg
Tip: swap to kilograms if you prefer. This slider is in t and will convert automatically.
90°
Assumptions: symmetrical lift, equal leg lengths, level pick points, steady lift. 3/4‑leg mode assumes
only 2 legs effectively carry the load unless your lift plan states otherwise.
Angle factor
—
Formula: 2 × cos(θ/2)
Tension per leg
—
Formula: Load Weight ÷ Angle Factor
Angle risk bar (rule‑of‑thumb)—
Minimum gear (3 options only):
—
Suggestions are based on required per‑leg WLL (tension × margin).
Quick sanity check values (for your entered load):
Included angle
Angle factor
Tension / leg
Disclaimer: This calculator is provided for educational purposes only. It does not replace a lift plan
or the judgment of a competent person. Always confirm Working Load Limits (WLL) using the sling or chain tag and
current manufacturer data before conducting any lift.
How it works
Included angle θ is the angle between sling legs at the hook.
Angle factor = 1 / cos(θ/2).
Tension per leg = Load / (2 × cos(θ/2)).
3/4‑leg mode assumes only 2 legs share the load unless your lift plan says otherwise.
This tool is educational. It doesn’t replace a lift plan or a competent person’s judgment. Always verify WLL against the specific sling/chain tag and manufacturer data.