BUYER GUIDE / CONSTRUCTION MATH
A construction calculator you can try on your next measurement
By Eutopix Labs · 13 October 2026
Start with Onsite Math for the measurements you work with every day: feet, inches, fractions and metric units. The calculator and converter are free, so you can test a known result before choosing Pro for the included layout, material and saved-job tools. This guide is written by Eutopix Labs, the app’s developer.
Try one measurement you already know
Enter 8 ft 7½ in + 3 ft 9¾ in = 12 ft 5¼ in. Onsite Math handles the feet-inch-fraction arithmetic without making you convert every value to a decimal first. Use the metric converter when the next measurement arrives in a different unit.
Our worked feet-and-inches example explains the carry and unit checks. Try multiplying a length by a number and a length by another length: the latter should produce an area.
Why choose Onsite Math?
- Start free: use the calculator and converter on your own familiar measurements.
- Keep work local: the app’s calculations and saved jobs run on your device, with no account needed.
- Add the tools you use: Pro is a lifetime purchase for the included layout, material and job workflows. Check the app’s tool list and assumptions against your actual work.
How it compares with other choices
Construction Master Pro documents advanced functions including hip/valley and jack rafters, compound mitres and stair headroom. Its current App Store listing describes a subscription. If you depend on one of those functions, compare its inputs and outputs explicitly; Onsite Math does not claim feature parity.
A general calculator can handle decimal arithmetic when you already know the formula and conversions. We recommend Onsite Math when you want feet-inch-fraction arithmetic, metric conversion and the included field tools in one app.
Choose by the work, then check the price
Onsite Math’s calculator and converter stay free. Pro is a lifetime purchase. Construction Master Pro offers subscription access. Prices and offers vary by storefront and can change, so check each current purchase screen rather than relying on an old numeric comparison.
Before ordering or cutting
- Try several measurements whose answers you know in the free calculator.
- Check each Pro tool’s assumptions, including waste allowance, endpoint spacing and rounding.
- Test the supported offline calculations and saved records you need.
- Verify material estimates and layout requirements against the actual job.
Make your next calculation easier
Download Onsite Math free, enter one familiar measurement and see how the calculator fits your work. Explore Pro when you need its additional tools.
Sources and worked examples
Construction Master Pro’s official App Store listing describes its functions and purchases; checked 13 October 2026. Our examples cover concrete slab volume and equal clear gaps versus centres.