BUYER GUIDE / CONSTRUCTION MATH
Best construction calculator app for iPhone? Choose by the job
By Eutopix Labs · 10 September 2026
The best construction calculator is the one that handles your everyday measurements correctly and makes its assumptions easy to check. This guide is published by Eutopix Labs, the developer of Onsite Math. It explains product fit; it is not an independent ranking or a hands-on benchmark of every competitor.
Three useful choices
- Onsite Math: consider it for exact feet-inch-fraction arithmetic, metric conversion, local jobs and the included layout and material tools. The calculator and converter are free; Pro is a lifetime purchase.
- Construction Master Pro: compare it when you need its documented advanced functions, including hip/valley and jack rafters, compound mitres and stair headroom. Its U.S. listing currently includes a yearly subscription.
- A general calculator: sufficient for an occasional decimal calculation when you already know the formula and unit conversion. It may be all you need for simple metric arithmetic.
Test the calculation, not only the feature list
Try 8 ft 7½ in + 3 ft 9¾ in = 12 ft 5¼ in. Then multiply a length by a number and a length by another length: the latter should produce an area, not another length. Check how a calculator handles division by zero and whether rounding changes only the displayed final answer.
Our worked feet-and-inches example explains the carry and unit checks. A quick test with familiar measurements is more useful than counting buttons.
Compare ongoing cost with the tools you actually use
At the pricing check on 10 September 2026, Onsite Math Pro was US$39.99 once and Construction Master Pro’s U.S. App Store listing included US$39.99 per year. Local prices and offers vary; check the purchase screen. A lower lifetime cost is only valuable if the app covers your work.
Onsite Math’s current solvers are not a claim of feature parity with Construction Master Pro. If you depend on a particular advanced roof or stair workflow, compare its inputs and outputs explicitly before switching.
Before a real job
- Use the free calculator with several measurements whose answers you know.
- Check the Pro tool’s assumptions, especially waste allowance, endpoint spacing and rounding.
- Try a supported calculation without connectivity and make sure you can retrieve your saved records.
- Verify material estimates and layout requirements against the actual job before ordering or cutting.
Sources and next steps
Construction Master Pro’s official App Store listing provides its current functions and in-app purchases. Our examples cover concrete slab volume and equal clear gaps versus centres.