Inches to MM Converter — Free Converter
Use our free inches to mm converter for instant inch to millimeter results. The inches to mm formula multiplies inches by 25.4. See also Wikipedia on the millimetre and the NIST unit conversion guide.
🔩 Inches to MM Converter
How to Convert Inches to Millimeters
Multiply by exactly 25.4 — the defined international standard.
Inches to MM Conversion Table
Common inch values converted to millimeters at a glance.
| Inch (in) | Millimeter (mm) |
|---|---|
| 0.5 in | 12.7 mm |
| 1 in | 25.4 mm |
| 2 in | 50.8 mm |
| 3 in | 76.2 mm |
| 5 in | 127 mm |
| 10 in | 254 mm |
| 15 in | 381 mm |
| 20 in | 508 mm |
| 25 in | 635 mm |
| 50 in | 1,270 mm |
Real-Life Inches to MM Examples
When your inch measurement needs to be in millimeters.
🔧 Tools & Hardware
US socket sets, wrenches, and drill bits are sized in inches; metric versions use millimetres. A 1/2-inch socket = 12.7 mm. A 3/4-inch drill bit = 19.05 mm. When shopping for replacement tools or working on metric-spec machinery, the mm equivalent is essential.
Automotive repair in metric-spec vehicles (most non-US cars) requires metric tools. Converting your existing inch-sized tools to mm tells you which metric size to buy as a replacement or upgrade.
🖥️ Screen Bezel & Panel Specs
Display manufacturers publish screen dimensions and bezel thickness in millimetres. If you know a monitor's bezel is about 0.5 inches = 12.7 mm, you can compare it against the spec sheet directly. A 1-inch border = 25.4 mm.
Tech integrators mounting screens in custom enclosures or cabinetry need precise mm dimensions to route cables and cut apertures. Converting inch measurements from US tooling specs to mm ensures millimetre-accurate fabrication.
🪛 3D Printing & Prototyping
3D printing software and CNC machines worldwide operate in millimetres. A part designed with a 2-inch hole = 50.8 mm. A 0.25-inch wall thickness = 6.35 mm. Entering inch dimensions directly into mm-native software without converting causes scaled errors.
US engineers and hobbyists designing in inches for international manufacturers must provide mm specs. Converting at the design stage — not after the prototype arrives — prevents costly reprints and rework.
💍 Ring & Jewellery Sizing
Ring diameters and jewellery wire gauges are specified in mm internationally. A US size 7 ring has an inner diameter of about 0.676 in = 17.17 mm. Jewellers worldwide work in mm for precision stone settings and band sizing.
Ordering custom jewellery from overseas workshops requires sending measurements in mm. Converting your inch-based ring size or bracelet length into mm gives the craftsperson the exact figure they need.
Frequently Asked Questions
Frequently Asked Questions
1 Inch (in) equals 25.4 Millimeters (mm).
Multiply the value in Inchs by 25.4. For example, 10 Inchs = 254 Millimeters.
Yes. ConvertNow uses precise factors for all unit calculations. Currency conversions use live exchange rates updated regularly.
Yes — type into the right-hand field to reverse the conversion.