Fractional Inch to Decimal Converter
Fractional inch to convert
Enter a fractional inch, such as 7 over 16, to convert
it to decimal inches, millimetres and centimetres.
Decimal inches
awaiting inputAwaiting input.
Enter a fraction to convert.
- Millimetres
- —
- Centimetres
- —
- Simplified fraction
- —
- Meters
- —
To convert a fractional inch to decimal and metric units, divide the numerator by the denominator, then multiply by 25.4 for millimetres. 7/16" = 7 ÷ 16 = 0.4375", and 0.4375 × 25.4 = 11.1125 mm.
From a Ruler to a Drawing
A fractional inch is what a tape measure or ruler shows; decimal inches and millimetres are what a drawing, a caliper or a spreadsheet expects.
Fractional measurements come off physical tools — a tape measure marked in sixteenths, a socket set labelled in eighths. The moment that measurement needs to go into a CAD drawing, a machining tolerance or a metric bill of materials, it has to become a decimal or millimetre value first, because those systems don't understand "7/16" as an input.
This is the exact reverse of the decimal to fractional inch converter: instead of rounding a decimal to the nearest tidy fraction, here you start with an exact fraction and expand it to its precise decimal and metric equivalents — no rounding involved at all.
The Fraction to Decimal & Metric Formula
Two steps take a fractional inch all the way to millimetres.
V is the fraction's decimal value, found by ordinary division. MM is that decimal multiplied by 25.4, the exact number of millimetres in one inch.
- NThe numerator of the fractional inch. In 7/16", N = 7.
- DThe denominator of the fractional inch. In 7/16", D = 16.
- VThe decimal inch value, N ÷ D.
- MMThe millimetre value, V × 25.4 — an exact conversion factor, not an approximation.
Worked calculation — 7/16"
- 7 ÷ 16 = 0.4375Divide the numerator by the denominator
- 0.4375 × 25.4 = 11.1125Multiply by the exact mm-per-inch factor
- 11.1125 ÷ 10 = 1.11125Divide by 10 for centimetres
7/16" = 0.4375" = 11.1125 mm = 1.11125 cm
Sixteenths of an Inch in Millimetres
Every sixteenth from 1/16" to a full inch, converted exactly.
| Fraction | Millimetres | Centimetres |
|---|---|---|
| 1/16" | 1.5875 mm | 0.15875 cm |
| 2/16" | 3.175 mm | 0.3175 cm |
| 3/16" | 4.7625 mm | 0.47625 cm |
| 4/16" | 6.35 mm | 0.635 cm |
| 5/16" | 7.9375 mm | 0.79375 cm |
| 6/16" | 9.525 mm | 0.9525 cm |
| 7/16" | 11.1125 mm | 1.11125 cm |
| 8/16" | 12.7 mm | 1.27 cm |
| 9/16" | 14.2875 mm | 1.42875 cm |
| 10/16" | 15.875 mm | 1.5875 cm |
| 11/16" | 17.4625 mm | 1.74625 cm |
| 12/16" | 19.05 mm | 1.905 cm |
| 13/16" | 20.6375 mm | 2.06375 cm |
| 14/16" | 22.225 mm | 2.2225 cm |
| 15/16" | 23.8125 mm | 2.38125 cm |
| 16/16" | 25.4 mm | 2.54 cm |
Converting Without a Calculator
- Divide the numerator by the denominator. 3 ÷ 8 = 0.375.
- Multiply the decimal by 25.4 for millimetres. 0.375 × 25.4 = 9.525 mm.
- Divide the millimetre value by 10 for centimetres, or by 1000 for meters. 9.525 mm = 0.9525 cm.
Frequently Asked Questions
How many millimeters is 7/16 of an inch?
7/16" equals 11.1125 mm. Convert to decimal first — 7 ÷ 16 = 0.4375" — then multiply by 25.4: 0.4375 × 25.4 = 11.1125 mm.
What is 1/2 inch in cm?
1/2" is 1.27 cm. As a decimal, 1/2" = 0.5", and 0.5 × 25.4 mm = 12.7 mm, which is 1.27 cm after dividing by 10.
Why do fractional inches convert to irregular millimeter values?
Because 25.4, the exact number of millimetres in an inch, isn't a round multiple of the power-of-two denominators (2, 4, 8, 16, 32, 64) that fractional inches use. Multiplying an eighth or sixteenth by 25.4 rarely lands on a whole or tidy decimal millimetre value — 1/3" would, but 1/16" gives 1.5875 mm.
Is 25.4 mm always exactly one inch?
Yes. Since the international yard and pound agreement of 1959, one inch has been defined as exactly 25.4 millimetres — not a rounded approximation. Every conversion on this page multiplies by that exact figure, so the millimetre results shown are exact, not estimates.
How do I convert a mixed number fraction, like 1 3/8", to mm?
Convert the mixed number to a decimal first: 1 3/8" = 1 + 0.375 = 1.375". Then multiply by 25.4: 1.375 × 25.4 = 34.925 mm. The whole-number part converts the same way as the fractional part — there's no separate rule for it.
Decimal & Fraction Tools
Every other calculator in this cluster, one click away.