Tools that do the math and show their work
Free construction calculators — every formula stated, every worked example verified against the same test vectors our apps use. Imperial and metric, switchable mid-calculation.
Calculators
- Concrete Slab Calculator
Concrete slab volume in cubic yards or cubic meters, plus 80 lb, 60 lb, or 25 kg bag counts — free, imperial + metric, with waste factor.
- Rafter Length Calculator
Common rafter length from run and roof pitch (rise-in-12 or degrees) — line length, rise, and plumb-cut angle. Free, imperial + metric.
- Stair Layout Calculator
Riser count, exact riser height, treads, and total run from floor-to-floor rise — with IRC and DIN 18065 comfort checks. Free, imperial + metric.
The apps we're building
Three field apps, one rule: pay once, own it forever. No subscriptions, no ads, no accounts required — they work fully offline.
- Tenon Calc
Construction calculator that turns any calculation into a client-ready, branded PDF quote. Feet-inch-fraction math, live metric⇄imperial switching.
- Tenon Cam
Timestamp field camera. No ads, no vendor logo — your logo on the stamp — and whole projects export as a PDF photo binder.
- Tenon Log
The solo-crew site diary: a day's record in under a minute, signed PDFs. Not per seat — your whole crew, one price.
Get the mobile apps when they launch
Tenon Calc, Tenon Cam, and Tenon Log — pay once, own forever. One email when each ships. No spam, unsubscribe anytime.