Sling Tension Calculator

Sling Tension Calculator gives riggers, crane operators, lifting supervisors and engineers the sling-leg tension for a lift in seconds — with a clear diagram, the full formula, and a check against your sling's rated capacity. Pick the hitch, enter the load and sling angle, and the result updates as you go. Lower sling angles mean higher tension; the app shows exactly how much. CALCULATE • Vertical, 2-leg bridle, 4-leg bridle, basket and choker hitches • Tension per leg and total sling force • Required capacity with an optional safety factor (1.0, 1.25, 1.5 or custom) • Capacity check against the rated capacity (WLL) you enter: PASS or CAPACITY EXCEEDED, with % of WLL used • Angle measured from horizontal or vertical — converted automatically SEE IT • Live sling diagram that redraws as you change the angle • Large, high-contrast result built for use on site • Angle guidance that flags increasing, high and very high tension UNDERSTAND IT • Show Formula on every result, with step-by-step working • Four-leg bridles let you choose how many legs are assumed to carry the load — because four physical legs rarely share load equally • Learn section: sling angle, configurations, capacity, load sharing and common mistakes, plus an angle-factor table UNITS • Load: kg, metric tonnes, lb, US tons • Results and capacity: kg, t, lb, US tons, N, kN, lbf • Metric and Imperial presets SAVE & SHARE • Automatic calculation history with search, filters and sort • Name calculations (e.g. "Warehouse Beam Lift") and save common setups as presets • Share a clean text summary or a PDF report via the iOS share sheet PRIVATE & OFFLINE • No account, no sign-up • Works 100% offline — calculations, history, diagrams and learning content • Your data stays on your device Designed for iPhone and iPad. IMPORTANT This calculator provides mathematical estimates for educational and planning purposes. It does not replace a qualified person, manufacturer's Working Load Limit tables, engineering calculations, lifting plans, or applicable regulations and standards. Always verify the sling type, hitch, angle, configuration, hardware, load conditions and manufacturer's rated capacity before lifting.