What is 3/8 as a decimal?

3/8 is exactly 0.375 as a decimal.

How many millimetres is 3/8 of an inch?

3/8 of an inch is 9.525 mm, computed with the exact definition 1 inch = 25.4 mm.

3/8

Fraction3/8

Decimal0.375

Percent37.5%

3 of 8 equal parts filled — the same share as a bar and as a circle.

Where the decimal comes from

3/8 equals 375/1,000 equals 0.375.

Multiply the top and bottom by 125 and the denominator becomes 1,000. A fraction over 1,000 is what a decimal is: 0.375 means 375 thousandths.

Every way to write it

Decimal: 0.375
Percent: 37.5%
Ratio: 3 : 8 (part to whole)
As inches: 3/8″ = 9.525 mm

Equivalent fractions

Multiply the top and bottom of 3/8 by the same number and the value does not change:

3/8 = 6/16 = 9/24 = 12/32 = 15/40 = 18/48 · more, or pick a denominator

On the number line

As a measurement

Read as inches, 3/8″ is 9.525 mm exactly. The nearest marks on the finer rules:

Rule	Nearest mark	Decimal inches	mm	Difference
16ths	3/8″	0.375	9.525	exact
32ths	3/8″	0.375	9.525	exact
64ths	3/8″	0.375	9.525	exact

Need a different rule or a tolerance? Nearest fraction · Within tolerance

Common questions

What is 3/8 as a decimal?: 3/8 is exactly 0.375 as a decimal.
What is 3/8 as a percentage?: 3/8 is exactly 37.5%.
How many millimetres is 3/8 of an inch?: 3/8 of an inch is 9.525 mm, computed with the exact definition 1 inch = 25.4 mm.

Fraction–decimal chartThe everyday set, printable.Rule charts16ths, 32nds, 64ths, 128ths.The rulerSee 3/8 in its place.

Where this comes from. Exact rational arithmetic on the values shown — fractions are pairs of integers until display, and inch–metric conversion uses 25.4 mm to the inch, exact by definition since 1959. See the full methodology.

3/8