MM → Inches
Working in millimeters and need a quick inches reference? This is your cheat sheet. Bookmark it, print it, use it forever.
0.5 mm to 30 mm · decimal + fraction
Quick anchors to memorize
25.4 mm
equals exactly
1.0000″
memorize this one
12.5 mm
is close to
1/2″
half inch landmark
6.5 mm
is close to
1/4″
quarter inch landmark
Full conversion table
mmdecimalfraction
mmdecimalfraction
whole mm
half mm
key anchor
How to actually use this
Tips for thinking in mm
- Start with 25.4. That’s 1 inch exactly. Everything else is just math from there. Half of 25.4 is 12.7, which is just about half an inch.
- Use the anchors as mental checkpoints. When you see a number, ask: is it closer to 6.5 (1/4″), 12.5 (1/2″), or 25.4 (1″)? That gets you in the ballpark instantly.
- Fractions are approximations. The decimal column is the exact conversion. The fraction column is the closest standard imperial fraction you’d find on a ruler, which is close enough for most design work.
- For laser and 3D print work, you’re usually dealing with tolerances in the 0.1-0.5mm range. That’s less than 1/32 of an inch, so if something fits in mm, it’s going to fit.
