Calculator
Formula used
Let x be the decimal inches and D the selected maximum denominator (2, 4, 8, 16, 32, or 64).
- Split x into whole inches w and fractional part r:
w = floor(x),r = x - w. - Compute the raw numerator:
n_raw = r × D. - Apply rounding: nearest →
n = round(n_raw)• down →n = floor(n_raw)• up →n = ceil(n_raw). - If
n == D, carry 1 to w and setn = 0. - Reduce
n/Dby dividing numerator and denominator by their greatest common divisor.
For improper output, compute N = w×D + n and display N/D. Also report the rounded decimal (w + n/D) and the absolute error from the original value.
How to use
- Enter your decimal inches value.
- Choose a maximum denominator to control precision.
- Select a rounding method that matches your requirement.
- Pick mixed or improper style for the display.
- Click Add to table to log the result below.
- Use Download CSV or Download PDF to export the table.
Results
| # | Input (in) | Denominator | Rounding | Fraction | Mixed | Improper | Rounded decimal | Error (in) | Timestamp |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 3.375 | 16 | Nearest | 3/8 | 3 3/8 | 27/8 | 3.375 | 0.0000 | |
| 2 | 2.625 | 16 | Nearest | 5/8 | 2 5/8 | 21/8 | 2.625 | 0.0000 | |
| 3 | 1.2 | 8 | Nearest | 1/4 | 1 1/4 | 10/8 | 1.25 | 0.0500 |
FAQs
1) What denominators are supported?
Halves, quarters, eighths, sixteenths, thirty-seconds, and sixty-fourths. Choose the highest you need for the desired precision.
2) Which rounding method should I use?
Nearest is typical. Use down for conservative cuts and up when you prefer slightly larger measurements.
3) Does the tool reduce fractions?
Yes. The numerator and denominator are divided by their greatest common divisor for a simplified fraction.
4) What if my fraction equals the denominator?
If the rounded numerator equals the denominator, one whole inch is carried and the fractional part becomes 0.
5) Can I see both mixed and improper?
Yes. The results table shows both styles, plus the rounded decimal and absolute error from your original value.
6) How accurate is sixty-fourths?
Sixty-fourths provide precision to 0.015625 inches per tick before rounding. Consider your tool tolerance and material expansion.
7) How do I export my data?
Use the CSV button for spreadsheets. Use the PDF button to generate a printable report right in your browser.