Slingwright Rigging Calculator

Slingwright is a rigging calculator and sling angle calculator for riggers, signal persons, crane crews, lift planners and students. It works like a hardware calculator: a safety-orange chassis, real keys and a clear LCD, with each answer labelled so you know what you are reading.

SLING ANGLES
• Sling angle from horizontal, typed or solved from any two of sling length, hook height and span
• Angle factor 1 ÷ sin(angle), with a built-in sling angle chart from 90° down to 20°: the factor, plus leg tension and horizontal force per 1000 for two legs
• Angles under 30° are flagged LOW ANG, as ASME B30.9 discourages them

LEG TENSION
• Tension per leg for 1 to 4 legs, with the vertical and horizontal force per leg
• For 3 or 4 legs only 2 are assumed to carry the load
• Horizontal force per leg: the compression in a spreader beam

OFFSET CENTRE OF GRAVITY
• Two-leg bridle: the load share at each pick point
• With the hook height set, each leg's tension, angle and length for a level lift with the hook over the centre of gravity
• Centre of gravity of several items along a line, with the total stored as the load

LOAD WEIGHT
• Estimated weight of a box or plate, round bar or pipe in steel, stainless, cast iron, aluminium, copper, concrete, water or wood
• Pounds and US tons, or kilograms and tonnes

PERCENT OF CAPACITY
• Type the rated capacity from the equipment tag or load chart and see the load and the leg tension as a percentage of it
• Slingwright holds no sling, hardware or crane capacities: you enter them

WORKS THE WAY YOU DO
• Feet and inches or metres
• A results strip shows every solved value at once
• 10 memories, a tape of your calculations, reference tables (angle factors, material densities) and a key guide
• Export a job strip: the tape with inputs, stamped and ready to attach to a lift plan, sign-off or take-off, as text or PDF

TRY PRO FREE FOR 7 DAYS
Try every feature free for 7 days, then keep Pro with a yearly subscription. Cancel anytime in Google Play. No ads, works offline.

PRIVATE BY DESIGN
Works offline, no account, no data collected.

How it's calculated: the formulas and tables behind every result, at https://wrightcalc.app/slingwright/

Questions or feedback: [email protected]

FOR LIFT PLANNING ONLY. Slingwright computes geometry and statics; it is not certified and does not replace a lift plan. Check every result against the rated capacities on the equipment tags and load charts, and have a qualified person review the lift. Weights from shapes use nominal densities: use the actual weight when it is known. The developer accepts no liability for loss, damage or injury arising from use.