RigCalcPro: Rigging Calculator

RigCalc Pro turns your iPhone into a complete rigging calculator for every rigger, crane operator, and lift supervisor in the field — 100% offline, no signal required. Get accurate sling tensions, load weights, and capacity checks before the load leaves the ground — all in one app, with no brand lock-in.

Stop guessing your rigging. Whether you're calculating sling leg tension at a tight angle, estimating the weight of a steel plate, finding the center of gravity of an asymmetric load, or checking crane capacity against the load chart, RigCalc Pro delivers the numbers you need to plan a safe lift.

RIGGING CALCULATORS:

• Sling Load Calculator — Leg tension for 1 to 4 leg slings. Enter the sling angle directly or let the app compute it from height and length. Instant warnings when angles drop below 30 degrees and tensions multiply.

• Load Weight Estimator (Premium) — Estimate load weight from shape and material. Plates, pipes, cylinders, blocks, and I-beams in steel, aluminum, concrete, wood, and more.

• Center of Gravity Calculator (Premium) — Two-point lifts on asymmetric loads. Get the share of load at each pick point and the CoG position before you rig.

• Crane Capacity Check (Premium) — Load weight plus rigging weight plus hook block against chart capacity. See utilization percentage and safety status at a glance.

• Drift / Headroom Calculator (Premium) — Hook height and sling lengths in, clearance above the load out. Know your headroom before the lift, not during it.

REFERENCE GUIDES:

• Shackle WLL Chart — Working load limits by shackle size for screw pin anchor shackles.

• Wire Rope Sling Capacity — Capacities by rope diameter and hitch: vertical, choker, and basket.

• Chain Sling Capacity — Grade 80 and Grade 100 chain by leg count and sling angle.

• Web Sling Capacity — Synthetic web sling capacities for every common hitch.

• Eyebolt Capacity — Rated loads with angle reduction factors.

• Crane Hand Signals — Illustrated guide to standard crane hand signals.

• Hitch Types Guide — Visual reference for vertical, choker, and basket hitches.

• Unit Converter — Tons, pounds, kilograms, feet, meters, and more.

YOUR DATA, YOUR WAY:

• Calculation History — Every calculation is saved automatically. Review and compare past results.

• 100% Offline — No internet required. Every calculation runs on-device. Use it on the deck, in the yard, or on remote sites with zero connectivity.

• Dark Mode — Designed for bright outdoor glare and low-light night shifts.

FREE vs PREMIUM:

Free includes the Sling Load Calculator, crane hand signals, hitch types guide, unit converter, and calculation history.

Premium unlocks the Load Weight Estimator, Center of Gravity, Crane Capacity Check, and Drift/Headroom calculators, all capacity reference charts, and every future calculator and reference tool as they are added.

IMPORTANT SAFETY NOTICE: RigCalc Pro is a planning aid for trained and qualified rigging personnel. All values are for reference only — always verify capacities with the manufacturer's tag and current ASME B30 / OSHA 1926.251 requirements before lifting. Never exceed rated capacities.

SUBSCRIPTION

Premium requires a paid auto-renewing subscription: US$1.99 per week (with a 1-week free trial) or US$19.99 per year (with a 1-month free trial). When the free trial ends, the subscription renews automatically and your Apple Account is charged, unless you cancel at least 24 hours before the current period ends. You can manage or cancel your subscription in your Apple Account settings.

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