Conversion formula

The conversion factor from millimeters to inches is 0.039370078740157, which means that 1 millimeter is equal to 0.039370078740157 inches:

1 mm = 0.039370078740157 in

To convert 521 millimeters into inches we have to multiply 521 by the conversion factor in order to get the length amount from millimeters to inches. We can also form a simple proportion to calculate the result:

1 mm → 0.039370078740157 in

521 mm → L_(in)

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

L_(in) = 521 mm × 0.039370078740157 in

L_(in) = 20.511811023622 in

The final result is:

521 mm → 20.511811023622 in

We conclude that 521 millimeters is equivalent to 20.511811023622 inches:

521 millimeters = 20.511811023622 inches

Alternative conversion

We can also convert by utilizing the inverse value of the conversion factor. In this case 1 inch is equal to 0.048752399232246 × 521 millimeters.

Another way is saying that 521 millimeters is equal to 1 ÷ 0.048752399232246 inches.

Approximate result

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

521 mm ≅ 20.512 in

An alternative is also that one inch is approximately zero point zero four nine times five hundred twenty-one millimeters.

Conversion table

millimeters to inches chart

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