Exact match at the selected denominator.
Decimal inch to fraction converter
Convert decimal inches to the nearest common fraction and millimeters. You can also enter a fraction like 3/8 or 1 1/2 to get decimal inches, mm, and thou.
Convert inches, fractions, and mm
Pick the input type, enter a value, then choose how fine the nearest inch fraction should be.
0.375 inch equals 3/8 inch, 9.525 mm, and 375 thou.
Common decimal inch to fraction chart
Quick answers for common shop, hardware, craft, and layout measurements.
| Decimal inch | Fraction | Millimeters | Thou |
|---|
How to use this converter
- Choose whether you are entering decimal inches, a fraction, or millimeters.
- Type the measurement, such as 0.3125, 5/16, or 8 mm.
- Select the nearest fraction denominator: 1/16, 1/32, 1/64, or another option.
- Use the result as a practical measuring approximation, especially when marking with a ruler or tape measure.
When rounding matters
A decimal inch can be an exact fraction, or it may land between two ruler marks. This tool shows the nearest selected fraction and the difference in thou so you can decide whether the rounded value is close enough.
For machining, drilling, and tight fit work, keep the decimal or millimeter value. For quick woodworking, craft, and layout marks, a nearby 1/16 or 1/32 inch fraction is often easier to use.
Decimal inch fraction FAQ
What is 0.375 as a fraction?
0.375 inch is exactly 3/8 inch. It is also 9.525 millimeters and 375 thou.
What is 0.125 as a fraction?
0.125 inch is exactly 1/8 inch. It is also 3.175 millimeters and 125 thou.
Can I enter mixed numbers?
Yes. Enter values like 1 1/2, 2-3/8, or 2 3/8. The converter treats them as inch fractions.