What is 1/20 as a decimal?

1/20 is exactly 0.05 as a decimal.

How many millimetres is 1/20 of an inch?

1/20 of an inch is 1.27 mm, computed with the exact definition 1 inch = 25.4 mm.

1/20

Fraction1/20

Decimal0.05

Percent5%

1 of 20 equal parts filled .

Where the decimal comes from

1/20 equals 5/100 equals 0.05.

Multiply the top and bottom by 5 and the denominator becomes 100. A fraction over 100 is what a decimal is: 0.05 means 5 hundredths.

5 of 100 squares — 0.05 of the whole. The same squares read as a percentage: 5%, because percent means per hundred.

Every way to write it

Decimal: 0.05
Percent: 5%
Ratio: 1 : 20 (part to whole)
As inches: 1/20″ = 1.27 mm

Equivalent fractions

Multiply the top and bottom of 1/20 by the same number and the value does not change:

1/20 = 2/40 = 3/60 = 4/80 = 5/100 = 6/120 · more, or pick a denominator

On the number line

As a measurement

Read as inches, 1/20″ is 1.27 mm exactly. The nearest marks on the finer rules:

Rule	Nearest mark	Decimal inches	mm	Difference
16ths	1/16″	0.0625	1.5875	+0.3175 mm
32ths	1/16″	0.0625	1.5875	+0.3175 mm
64ths	3/64″	0.046875	1.1906	−0.0794 mm

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

Common questions

What is 1/20 as a decimal?: 1/20 is exactly 0.05 as a decimal.
What is 1/20 as a percentage?: 1/20 is exactly 5%.
How many millimetres is 1/20 of an inch?: 1/20 of an inch is 1.27 mm, computed with the exact definition 1 inch = 25.4 mm.

Fraction–decimal chartThe everyday set, printable.Rule charts16ths, 32nds, 64ths, 128ths.The rulerSee 1/20 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.