Calculator
Fraction and measurement helper
Shop math in tape-measure fractions. Type sizes the way you read them, like 23 1/2 or 23-1/2.
JavaScript is off, so this page cannot do the math. The tips below still work by hand.
Fraction math
Inches. Examples: 3 5/16, 3-5/16, 3.3125, 2' 6".
Result —
Decimal —
Inches and millimeters
Type in either box. 1 inch = 25.4 mm exactly; results are rounded for display.
Equal spacing
Space slats, balusters, or shelf pins evenly along a board.
Gap —
| Slat | Left edge | Center | Right edge |
|---|
Doing it by hand
- To add fractions, give them the same bottom number first. 5/16 + 7/8 is 5/16 + 14/16 = 19/16, which is 1 3/16.
- Equal gaps: take the board length, subtract all the slat widths, and divide by the number of slats plus one. Ten ¾″ slats across 36″: (36 − 7.5) ÷ 11 = 2.5909″, a bit under 2 19/32″.
- Mark from one end with the same tape, and check your last mark against the far end. Small rounding errors add up across many slats.
This tool is for planning. Results are rounded to the nearest 1/16″ or 1/32″ (your choice), so small errors can add up across many parts. Measure twice before you cut.
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