Enter your measurement
Formula used
Decimal inches = Whole inches + (Numerator ÷ Denominator) Total inches = (Feet × 12) + Inches + (Numerator ÷ Denominator) Decimal feet = Total inches ÷ 12 Millimeters = Decimal inches × 25.4 Centimeters = Decimal inches × 2.54
How to use this calculator
- Select the required conversion mode.
- Enter the measurement using separate fields or quick typing.
- Choose decimal precision, rounding, and fraction accuracy.
- Press Calculate to view conversions and calculation steps.
- Copy, print, share, or download the result.
Common inch fractions
| Inch measurement | Decimal inches | Decimal feet | Millimeters |
|---|---|---|---|
| 1/8 inch | 0.125 | 0.010417 | 3.175 |
| 1/4 inch | 0.25 | 0.020833 | 6.35 |
| 3/8 inch | 0.375 | 0.03125 | 9.525 |
| 1/2 inch | 0.5 | 0.041667 | 12.7 |
| 5/8 inch | 0.625 | 0.052083 | 15.875 |
| 3/4 inch | 0.75 | 0.0625 | 19.05 |
| 7/8 inch | 0.875 | 0.072917 | 22.225 |
Worked examples
| Input | Operation | Result |
|---|---|---|
| 5 3/8 inches | 5 + (3 ÷ 8) | 5.375 inches |
| 2 ft 6 1/2 in | ((2 × 12) + 6.5) ÷ 12 | 2.541667 feet |
| 7.6875 inches | 0.6875 × 16 = 11 | 7 11/16 inches |
Accuracy and rounding notes
Higher denominators provide finer fractional accuracy. Machining often uses thirty-seconds or sixty-fourths. Construction commonly uses eighths or sixteenths for measurements.
Standard rounding gives the closest displayed value. Upward rounding always increases the stored measurement slightly. Downward rounding always reduces the stored measurement slightly.
Frequently asked questions
What is a decimal inch?
A decimal inch expresses an inch fraction as a base-ten number. For example, one-half inch equals 0.5 inches. This format simplifies calculations in technical measurement work.
How do I convert 3/8 inch?
Divide three by eight to obtain the decimal value. The resulting value is 0.375 decimal inches. The same length equals 9.525 millimeters exactly.
Can I enter mixed measurements?
Yes, the quick field accepts common mixed formats. You may enter 5 3/8 or 5-3/8. Decimal entries such as 5.375 also work directly.
What denominator should I select?
Select the denominator matching your required measurement precision. Sixteenths work well for many construction projects. Sixty-fourths provide finer accuracy for detailed machining tasks.
Does the calculator simplify fractions?
Yes, converted fractions are reduced to their simplest form. Eight thirty-seconds becomes one-quarter automatically. Improper fractions are displayed as readable mixed numbers.
How are millimeters calculated?
Every inch equals exactly 25.4 millimeters. The calculator multiplies decimal inches by 25.4. This standard conversion supports engineering and international measurement work.
What does rounding difference mean?
Rounding difference shows the change from the original value. Positive numbers indicate an increased rounded measurement. Negative numbers indicate the rounded measurement became smaller.
Can I convert decimal feet?
Yes, select decimal feet to feet and inches. The calculator separates complete feet from remaining inches. It then converts the remainder into a fraction.
Can I export the result?
Yes, results can be copied or downloaded as CSV. PDF export creates a clean calculation summary. Printing and sharing options are also included.