If you've ever pulled out your phone's calculator on a job site, tried to add 12 ft 6-3/8 in to 0.63 m, and given up — HammerCalc is built for exactly that moment.
What it does
HammerCalc replaces the awkward juggling of a standard calculator, a unit converter, and a fraction-to-decimal lookup. You enter measurements naturally, combine imperial and metric in one equation, and get an instant, accurate result you can convert to any unit with a single tap.
On top of the calculator itself, it bundles the tools a tradesperson reaches for again and again:
- Multi-unit math — feet, inches, millimeters and meters together in one calculation
- Tape Measure widget — tap fractions off a ruler instead of typing them
- Custom fraction rounding — 1/16", 1/32", 1/64", or decimal
- Specialized tools — stairs, rafters, roofs, circle & arc, triangle & polygon, square footage, and drywall, each with sliders and a live diagram
- Built-in plan viewer — open PDFs or photos and jump back to the exact page, zoom and position later
- Notes system — save any calculation into a project note with full history
Who it's for
HammerCalc is made for people who work with precise measurements: carpenters, contractors, framers, engineers, machinists, architects, designers, estimators, and inspectors. If your day involves a tape measure and a set of plans, it's built for you. It's equally at home for a serious DIYer tackling a deck, a staircase, or a tiling job who wants pro-grade answers without the guesswork.
How it works
Type an equation the way you'd say it out loud. Need a fraction? Tap it on the Tape Measure. Need a stair layout? Open the Stair tool, drag the sliders, and read the rise, run, and stringer values off a diagram that updates in real time. Working from a drawing? Load the PDF in the plan viewer, and when you switch back to the keypad your place is saved. Found a number worth keeping? Drop it into a note.
"12 ft 6-3/8 in + 0.63 m = 14 ft 7-3/16 in" — one line, mixed units, exact fraction. That's the whole idea.
What makes it different
Plenty of construction calculators exist. HammerCalc's focus is speed and clarity for everyday measuring work: mixing units in one running equation, the fastest possible fraction entry, and keeping your plans and notes in the same place so you're not app-switching mid-task. It also has a modern, legible interface with dark mode for low-light sites — and, notably, it collects no data; everything stays on your device.
If you want a detailed head-to-head with the other popular options, see our comparison of HammerCalc vs Construction Master Pro.
Platforms and pricing
HammerCalc runs on iPhone (iOS 16+), iPad (iPadOS 16+), and Mac (macOS 12+), and one subscription covers all of your Apple devices. It starts with a 7-day free trial, then costs $3.99/month or $24.99/year (USD; pricing varies by region). You can cancel anytime from your Apple ID subscription settings.