Digital calipers and CAD drawings give decimal inches, while tape measures are marked in halves, quarters, eighths, sixteenths and sometimes thirty-seconds. This converts between the two.
How to use the Inches to Fraction Calculator
- Decimal measurement
- Precision
Results update as you type, and every field accepts the units shown in its menu.
How it works
Your value is multiplied by the chosen denominator, rounded to the nearest whole number and divided back, then reduced to its simplest fraction.
Decimal to fraction chart (1/16″)
| Fraction | Decimal inch | mm |
|---|---|---|
| 1/16″ | 0.0625 | 1.587 |
| 1/8″ | 0.1250 | 3.175 |
| 3/16″ | 0.1875 | 4.762 |
| 1/4″ | 0.2500 | 6.350 |
| 5/16″ | 0.3125 | 7.938 |
| 3/8″ | 0.3750 | 9.525 |
| 7/16″ | 0.4375 | 11.112 |
| 1/2″ | 0.5000 | 12.700 |
| 9/16″ | 0.5625 | 14.287 |
| 5/8″ | 0.6250 | 15.875 |
| 11/16″ | 0.6875 | 17.462 |
| 3/4″ | 0.7500 | 19.050 |
| 13/16″ | 0.8125 | 20.637 |
| 7/8″ | 0.8750 | 22.225 |
| 15/16″ | 0.9375 | 23.812 |
Inputs explained
| Field | What to enter |
|---|---|
| Decimal measurement | Units: in, cm, mm, ft |
| Precision | Choose one: 1/2″, 1/4″, 1/8″, 1/16″ … |
What each result means
- Nearest fraction = round([Decimal measurement] ÷ 0.0254 × [Precision]) ÷ [Precision]
- In feet and inches = round([Decimal measurement] ÷ 0.0254 × [Precision]) ÷ [Precision]
- Rounding error = (round([Decimal measurement] ÷ 0.0254 × [Precision]) ÷ [Precision] – [Decimal measurement] ÷ 0.0254) × 25.4
- Exact value in mm = [Decimal measurement] × 1000
Formula
fraction = round(decimal × denominator) ÷ denominatorWorked example
Inputs — Decimal measurement: 2.3125 in; Precision: 1/16″.
Results — Nearest fraction = 2 5/16; In feet and inches = 0 ft 2 5/16 in; Rounding error = 0 mm; Exact value in mm = 58.738 mm.
Frequently asked questions
What is 0.375 inch as a fraction?
3/8″.
What is 0.6 inch to the nearest 1/16?
5/8″ (0.625″).
How do I convert mm to a fraction of an inch?
Choose mm as the unit; the calculator converts to inches first.
What formula does the Inches to Fraction Calculator use?
fraction = round(decimal × denominator) ÷ denominator.