## Conversion formula

The conversion factor from inches to millimeters is 25.4, which means that 1 inch is equal to 25.4 millimeters:

1 in = 25.4 mm

To convert 20 inches into millimeters we have to multiply 20 by the conversion factor in order to get the length amount from inches to millimeters. We can also form a simple proportion to calculate the result:

1 in → 25.4 mm

20 in → L(mm)

Solve the above proportion to obtain the length L in millimeters:

L(mm) = 20 in × 25.4 mm

L(mm) = 508 mm

The final result is:

20 in → 508 mm

We conclude that 20 inches is equivalent to 508 millimeters:

20 inches = 508 millimeters ## Alternative conversion

We can also convert by utilizing the inverse value of the conversion factor. In this case 1 millimeter is equal to 0.0019685039370079 × 20 inches.

Another way is saying that 20 inches is equal to 1 ÷ 0.0019685039370079 millimeters.

## Approximate result

For practical purposes we can round our final result to an approximate numerical value. We can say that twenty inches is approximately five hundred eight millimeters:

20 in ≅ 508 mm

An alternative is also that one millimeter is approximately zero point zero zero two times twenty inches.

## Conversion table

### inches to millimeters chart

For quick reference purposes, below is the conversion table you can use to convert from inches to millimeters

inches (in) millimeters (mm)
21 inches 533.4 millimeters
22 inches 558.8 millimeters
23 inches 584.2 millimeters
24 inches 609.6 millimeters
25 inches 635 millimeters
26 inches 660.4 millimeters
27 inches 685.8 millimeters
28 inches 711.2 millimeters
29 inches 736.6 millimeters
30 inches 762 millimeters