RigMaster: Rigging Calculator
RigMaster is the rigging calculator built for working riggers, crane operators, and signal persons.
Version 1.5.0 Updated 2026-09-16 Requires iOS 17.0 Size 5 MB Price Free
What it does
Lift Plan Pdf (Pro)
- Turn any calculation into a one-page lift plan: diagram, inputs, results
- Room for notes and three signature lines — prepared by, signature, date
- Share it straight to the supervisor from the toolbar
Ipad & Units
- Universal app — two-column layout on iPad, any orientation
- Metric or imperial — kg and metres or lb and feet, switch any time
- Live sling diagram with the angle and tension on every leg
Free Calculators
- Sling Tension — 2-leg picks by angle, or by sling length & height (the way you actually measure)
- Hitch Capacity — vertical, choker, and basket capacity from YOUR sling's tag rating
- Angle Reference — the tension multiplier table, always in your pocket
Pro Calculators
- 3 & 4-leg bridles with rigid/flexible load sharing
- Unequal Legs / CoG Offset — tension per leg when the center of gravity isn't centered
- Load Weight Estimator — steel, concrete, aluminum and more, by shape and dimensions
- Ad-free
Questions people ask about RigMaster
Does it work offline?
Yes. Every calculation runs on the phone. No signal needed on site.
Do I need an account?
No. There is no login and no sign-up.
What is free?
Sling Tension, Hitch Capacity and the Angle Reference table are free. Pro adds 3 and 4-leg bridles, unequal legs with CoG offset, the load weight estimator and the lift plan PDF, and removes the ads.
Metric or imperial?
Both, switchable at any time — kg and metres, or lb and feet.
Can I hand the result to the supervisor?
Yes. Pro turns any calculation into a one-page lift plan PDF: diagram, inputs, results, notes and three signature lines.
Does it replace the sling tag or the load chart?
No. It is an estimation aid for qualified riggers. The sling tag, the load chart and your site's rigging plan always come first.
Does it work on iPad?
Yes. Universal app, two-column layout on iPad, any orientation.
What's new in 1.5.0
Corrected the rigging terminology inside the app. Several languages had been machine-translated with the wrong sense of the word: "sling" came out as the catapult, "leg" as the body part, "hitch" as a jerk, and in one language "unequal legs" read as "equal legs" — on the screen that splits the load between uneven legs. Thirty-two terms rewritten by hand across seven languages.
Privacy and support
RigMaster works offline and does not require an account. Read the privacy policy and the terms for this app, or write to us if something is wrong.