20 inches to millimeters

20 inches = 508 millimeters

Rounded to a practical precision: 508 mm.

inches

millimeters

How the calculation works

One inch is 25.4 millimeters, so:

20 in × 25.4 = 508 mm

Reversing it, 508 millimeters ÷ 25.4 returns 20 inches.

Nearby values

Inches	Millimeters
16 in	406.4 mm
17 in	431.8 mm
18 in	457.2 mm
19 in	482.6 mm
20 in	508 mm
21 in	533.4 mm
22 in	558.8 mm
23 in	584.2 mm
24 in	609.6 mm

About these units

Inch (in) — An inch is exactly 25.4 millimetres and is used for screen sizes, pipe diameters and paper dimensions.

Millimeter (mm) — A millimetre is one thousandth of a metre and is the default unit on engineering drawings and rulers.

Frequently asked questions

How many millimeters is 20 inches?

20 inches is 508 millimeters.

How do I convert inches to millimeters myself?

Multiply by 25.4. To go back, divide by 25.4 — or multiply by 0.0393701.

Is this figure exact?

The conversion factor between the inch and the millimeter is fixed by definition. The figure above is rounded for readability; the converter carries full precision.

Convert other values

Full inches to millimeters converter · All length converters