Why we store everything in millimetres
Display in whatever units you like — but pick one canonical unit under the hood, or rounding will eat you alive.
Start Here shows measurements in millimetres or inches, your choice. But internally, every value is stored in millimetres. That's a deliberate engineering decision.
Convert at the edges, not the middle
The moment you store the same measurement in two units, they drift. Round-trip a value through inches and back and you accumulate error. Store one canonical unit and convert only for display and export, and the numbers stay exact.
It keeps exports honest
A cut list that says 240.0mm and one that says 9.449in should describe the same cut. Because we convert from a single mm source at render time, they always do — no matter which unit you were looking at when you entered it.
Small decision, big payoff: no mystery gaps at glue-up.
Frequently asked questions
- Why store measurements in millimetres instead of inches?
- Storing one canonical unit and converting only for display keeps the numbers exact. The moment you store the same measurement in two units they drift, and round-tripping a value through inches and back accumulates rounding error.
- Can I still work in inches?
- Yes. Start Here displays in millimetres or inches, your choice — the mm-only rule is internal. You enter and read whatever unit you like; the storage underneath stays in millimetres.
- Does converting units introduce error?
- Only if you convert in the middle. Convert at the edges — display and export — from a single mm source, and a cut list reading 240.0mm and one reading 9.449in describe the exact same cut. No mystery gaps at glue-up.