📏 Length converter

Inches to Millimeters Converter

Convert inches (in) to millimeters (mm) instantly. Includes formula, worked example, and a full reference chart from 1 to 1000 in.

Inches

Millimeters

How to convert inches to millimeters

One inch equals exactly 25.4 millimeters. To convert inches to millimeters, multiply the inch value by 25.4. This is a commonly used conversion in engineering and machining.

Formula

millimeters = inches × 25.4

Worked example

Convert 1 in to mm:
1 in × 25.4 → 25.4 mm

Common inches to millimeters values

Quick reference for common inch values:

1 in = 25.4 mm
5 in = 127 mm
10 in = 254 mm
100 in = 2,540 mm

Inches to Millimeters conversion table

Full reference chart — useful for cooking, fitness, engineering, or homework.

Inches	Millimeters
1 in	25.4 mm
2 in	50.8 mm
3 in	76.2 mm
5 in	127 mm
10 in	254 mm
20 in	508 mm
25 in	635 mm
50 in	1,270 mm
75 in	1,905 mm
100 in	2,540 mm
250 in	6,350 mm
500 in	12,700 mm
1000 in	25,400 mm

Millimeters to Inches table (reverse)

Looking the other way? Here's the reverse conversion:

Millimeters	Inches
1 mm	0.0393701 in
2 mm	0.0787402 in
3 mm	0.11811 in
5 mm	0.19685 in
10 mm	0.393701 in
20 mm	0.787402 in
25 mm	0.984252 in
50 mm	1.968504 in
75 mm	2.952756 in
100 mm	3.937008 in
250 mm	9.84252 in
500 mm	19.685039 in
1000 mm	39.370079 in

Frequently asked questions

How many millimeters are in 1 inch?

There are 25.4 mm in 1 in.

How many millimeters are in 10 inches?

10 in = 254 mm.

How many inches are in 1 millimeter?

1 mm = 0.0393701 in.

What is the formula to convert inches to millimeters?

The formula is millimeters = inches × 25.4.