Feet & Fraction Calculator
Add, subtract, multiply, and divide feet-inch-fraction measurements with exact rational math — free in your browser. The iPhone app keeps construction-length math handy without a laptop.
Feet & Fraction Calculator
Add, subtract, multiply, or divide construction measurements with exact fraction math.
Left measurement
Right measurement
Factor
Result
- Expression
- Decimal feet
- Total inches
App screenshots
Real Feet & Fraction Calculator screens from the App Store listing.
How to use this calculator
- Enter feet, inches, and optional fraction for each operand.
- Choose operation and precision (denominator limit for results).
- For multiply/divide, use a numeric factor on the right when not adding lengths.
Features
- Feet + inches + fraction inputs
- Exact rational arithmetic
- Precision down to 1/64″
- Decimal feet and inches
- Offline iPhone workflow
Formula
Measurements convert to rational inches internally; results are rounded to your chosen fraction precision for display.
5′ 6½″ + 2′ 3¼″
Sum = 7′ 9¾″ (exact rational inches preserved before rounding for display).
Practical notes
- Precision controls the maximum denominator shown (up to 1/64″).
Take it to the job site
Use Feet & Fraction Calculator on your iPhone for fast repeat calculations and the full native workflow — wherever you're working.
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Related guides
- How to Lay Out Stair Stringers — Translate rise/run math into a stringer cut layout.
- How to Calculate Board Feet — Use the classic lumber board-foot formula.
- Feet, Inches, and Fraction Math on the Job — Add and subtract construction measurements without decimal mistakes.
FAQ
Can I type inches like 6 1/2?
Yes. The inches field accepts whole inches, decimals, or fractions like 6 1/2 or 6.5.
Always verify critical cuts on site with a physical tape.