1/3 as a decimal
1/3 = 0.(3) (0.333333…) inches = 8.4667 mm.
0.(3)
1/3 of an inch — the bracketed digits repeat forever, so this form is exact where 0.333333… is not
Millimetres
8.4667 mm
Centimetres
0.84667 cm
Percent
33.3333%
Decimal
repeats
Where 1/3 falls at each precision, and whether the mark is the value exactly
| Rule | Nearest mark | Exact? |
|---|---|---|
| 1/16 | 5/16 | nearest |
| 1/32 | 11/32 | nearest |
| 1/64 | 21/64 | nearest |
Converting 1/3 to a decimal
A fraction is a division. 1/3 = 1 ÷ 3 = 0.(3) (0.333333…). The decimal repeats forever, written 0.(3) with the repeating digits bracketed. That happens because 3 factors into 3, which includes a prime other than 2 or 5 — so no power of ten is divisible by it and the long division never terminates.
In metric that is 8.4667 millimetres (0.84667 cm), since one inch is exactly 25.4 mm. As a percentage of an inch it is 33.3333%.
1/3 is not a mark on any imperial rule — the denominators on a rule are all powers of two, and 3 is not one. The nearest marks are 5/16 on a 1/16 rule, 11/32 on a 1/32 rule, 21/64 on a 1/64 rule, none of them exact.
Going the other way
To turn 0.333333 back into a fraction, pick the precision you are working to and multiply. At 1/16: 0.333333 × 16 = 5.3333, giving 5/16 after rounding to the nearest mark. At 1/32: 0.333333 × 32 = 10.6667, giving 11/32 after rounding to the nearest mark. At 1/64: 0.333333 × 64 = 21.3333, giving 21/64 after rounding to the nearest mark.
What is 1/3 as a decimal?
1/3 as a decimal is 0.(3) (0.333333…). Divide the numerator by the denominator: 1 ÷ 3 = 0.(3) (0.333333…). The division never comes out exactly, so the digits repeat.
What is 0.(3) (0.333333…) as a fraction?
0.333333… as a fraction is 1/3, in lowest terms.
How many millimetres is 1/3 of an inch?
1/3 of an inch is 8.4667 mm, or 0.84667 cm. An inch has been defined as exactly 25.4 mm since 1959, so this conversion is a definition rather than a measurement.
Where is 1/3 on a tape measure?
1/3 is not a mark on any imperial rule — the denominators on a rule are all powers of two, and 3 is not one. The nearest marks are 5/16 on a 1/16 rule, 11/32 on a 1/32 rule, 21/64 on a 1/64 rule, none of them exact.