INCHES TO DECIMAL CALCULATOR
How it works
A tape reading of 5 and 5/8 inches.
- Convert the fraction: 5/8 = 5 ÷ 8 = 0.625.
- Add the whole inches: 5 + 0.625 = 5.625 inches.
- Divide by 12 for feet: 5.625 ÷ 12 = 0.46875 feet.
- Multiply by 25.4 for millimetres: 5.625 × 25.4 = 142.875 mm.
5.625 inches — 0.46875 feet, or 142.875 millimetres.
Constants
| Constant | Value |
|---|---|
| Millimetres per inch | 25.4 mm |
| Inches per foot | 12 in |
| Sixteenths as decimals | 1/16 = 0.0625, 3/16 = 0.1875, 5/8 = 0.625 |
SOURCE — 1 inch = 25.4 mm exactly, by international definition (1959).
SOURCE — 1 foot = 12 inches, by definition.
SOURCE — n/16 as a decimal is n ÷ 16; since 16 is a power of two, every sixteenth divides exactly, with no repeating digits.
Quick answers
5-5/8 inches equals exactly 5.625 decimal inches. Every sixteenth converts to a decimal with no repeating digits, because 16 is a power of two.
5.625 inches is 0.46875 feet — divide decimal inches by 12 to get decimal feet, the same division this calculator runs on every submit.
5.625 inches is 142.875 millimetres exactly, because one inch is defined as exactly 25.4 millimetres — the conversion never rounds.
3/16 inch is 0.1875 as a decimal, and 5/8 inch is 0.625 — every tape fraction from 1/16 to 15/16 converts to an exact decimal, never a repeating one.
A tape read to the nearest sixteenth carries four decimal places of real precision: 1/16 = 0.0625, and a finer measurement only needs more digits, not different math.
FAQ
What is 5/8 as a decimal?
0.625. Divide the numerator by the denominator: 5 ÷ 8 = 0.625 — and because 8 is a power of two, the division ends cleanly with no repeating digits.
What is 3/16 as a decimal?
0.1875. Any sixteenth converts the same way: divide the numerator by 16. Every result from 1/16 through 15/16 terminates exactly, the way 5/8 = 0.625 does.
How do I read a tape measure in decimals?
Read the whole inch, then the nearest fraction mark, then divide that fraction. A reading of 5 and 5/8 inches is 5 + 0.625 = 5.625 decimal inches — that whole conversion is what this page does.
How do I convert inches to millimetres?
Multiply decimal inches by 25.4. The factor is exact, not approximate, because an inch has been legally defined as 25.4 millimetres since 1959, so 5.625 inches is exactly 142.875 millimetres.
How do I convert inches to feet?
Divide decimal inches by 12. 5.625 inches ÷ 12 = 0.46875 feet — the same division whether the inches came from a whole number or a fraction.
Why does my fraction need a denominator?
Because 3 alone is not a fraction — 3/8 and 3/16 are different numbers, 0.375 and 0.1875. Leaving the denominator blank is a real ambiguity, so this calculator asks rather than guessing which one you meant.