Fraction to Decimal Calculator
With value 0.375, fraction to decimal comes to 0.37500 — as a decimal. It is reached in 6 steps, the last of which is value, and each one is printed on the page with its numbers filled in. The formula is the one published by NIST Office of Weights and Measures, not an approximation fitted to it.
Converts fractions to decimals and back, to the nearest 16th, 32nd and 64th, with the millimeter equivalent.
Formula and sources checked · How we check
Value 3/8
0.37500
As a decimal for the example below. Editing a field recomputes the calculator below; this figure holds the answer the page was loaded with.
It is written into the HTML rather than drawn by a script, so a search engine reading this page without running JavaScript still finds an answer.
- As a decimal
0.375- In sixteenths
round(0.375 * 16)6 /16- In thirty-seconds
round(0.375 * 32)12 /32- In sixty-fourths
round(0.375 * 64)24 /64- As millimeters, treating it as inches
0.375 * 25.49.525 mm- Error from rounding to the nearest 16th
abs(0.375 - round(0.375 * 16) / 16)0 in
Ask about this in the chatInch Fraction to Decimal Chart
Worked example
3/8 is 0.375 exactly — 6/16, 12/32, 24/64 and 9.525 mm. Fractions with a power-of-two denominator convert exactly; 1/3 does not, which is why tape measures are divided in halves all the way down rather than in thirds.
How to work it out yourself
- 1.Type the fraction directly, as 5/8 or 3 1/4. It parses the same way the rest of the site does.
- 2.Read the nearest sixteenth, thirty-second and sixty-fourth. A tape measure is marked in those, so the decimal alone does not tell you where to put the pencil.
- 3.Check the rounding error line before cutting. A decimal that lands between marks is where the sixteenth you choose decides whether the joint closes.
Inch fraction to decimal and millimeter chart
| Value | As a decimal | As millimeters, treating it as inches |
|---|---|---|
| 1/16 | 0.06250 | 1.59 mm |
| 1/8 | 0.12500 | 3.18 mm |
| 3/16 | 0.18750 | 4.76 mm |
| 1/4 | 0.25000 | 6.35 mm |
| 5/16 | 0.31250 | 7.94 mm |
| 3/8 | 0.37500 | 9.52 mm |
| 7/16 | 0.43750 | 11.11 mm |
| 1/2 | 0.50000 | 12.7 mm |
| 9/16 | 0.56250 | 14.29 mm |
| 5/8 | 0.62500 | 15.88 mm |
| 11/16 | 0.68750 | 17.46 mm |
| 3/4 | 0.75000 | 19.05 mm |
| 13/16 | 0.81250 | 20.64 mm |
| 7/8 | 0.87500 | 22.22 mm |
| 15/16 | 0.93750 | 23.81 mm |
Every sixteenth of an inch. Fractions with a power-of-two denominator convert exactly; thirds and fifths never do.
The formula
- As a decimal
- In sixteenths
round(0.375 * 16) - In thirty-seconds
round(0.375 * 32) - In sixty-fourths
round(0.375 * 64) - As millimeters, treating it as inches
0.375 * 25.4 - Error from rounding to the nearest 16th
abs(0.375 - round(0.375 * 16) / 16)
Source: NIST Office of Weights and Measures, ASME Y14.5 dimensioning and tolerancing
Questions people actually ask
- Why are tape measures divided into sixteenths?
- Repeated halving. Halving a foot gives 6 in, then 3, then 1 1/2, and so on — every mark is reachable by folding, which is how the system worked before precision printing. Thirds and fifths cannot be found that way.
- How precise is the nearest 1/16?
- Within 1/32 in, or 0.031 in — about 0.8 mm. That is finer than wood moves seasonally, which is why framing works in sixteenths and machining does not.
- What is 5/4 lumber in decimals?
- 1.25 in nominal. Quarter sizing counts quarters of an inch of rough thickness: 4/4 is 1 in, 5/4 is 1.25, 8/4 is 2. After surfacing, 5/4 decking actually measures about 1 in.
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- Rounding CalculatorA number rounded every way there is — half up, half to even, down, up and truncated — with the ones that disagree shown together.
Where this one stops
Read first
- How to Read a Tape Measure — Why the marks are different lengths, and how to read a sixteenth without counting them: each halving is drawn one step shorter than the one above it.
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