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Feet and Inches Calculator

Arithmetic in ft and in. Free online Feet and Inches Calculator. Calculate feet and inches online — fast, accurate, mobile-friendly, no signup needed.

Total (ft’ in”)
8' 11"

Derivation

  1. ├── 01Givenft1 = 5, in1 = 7, ft2 = 3, in2 = 4
  2. ├── 02Formula{const t=12 × e.ft1+e.in1+(12 × e.ft2+e.in2),a=floor(t / 12),n=t%12;return"".concat(a,"' ").concat(n,'"')}
  3. ├── 03Substitute{const t=12 × e.5+e.7+(12 × e.3+e.4),a=floor(t / 12),n=t%12;return"".concat(a,"' ").concat(n,'"')}
  4. └── 04Compute Total (ft’ in”)—
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§01What is

Understanding the Feet and Inches Calculator

The Feet and Inches Calculator computes Total (ft’ in”) from 4 inputs: feet 1, inches 1, feet 2, inches 2. Arithmetic in ft and in.

On a construction site, estimates that come in 10% off add up to six-figure overruns. Running the quantities with a calculator instead of a rule-of-thumb gets you closer to the truth with zero extra effort. The Feet and Inches Calculator sits in that toolkit — it arithmetic in ft and in. Enter your numbers above and the result updates instantly; every step of the math is shown in the Derivation panel so you can see exactly how the answer was reached.

§02The Formula

How it’s calculated

{const t=12 × e.ft1+e.in1+(12 × e.ft2+e.in2),a=floor(t / 12),n=t%12;return"".concat(a,"' ").concat(n,'"')}

Where

ft1
Feet 1
in1
Inches 1
ft2
Feet 2
in2
Inches 2
§03Practical Example

Step-by-step walkthrough

Scenario

Apply the formula to a realistic set of inputs: Feet 1 = 5, Inches 1 = 7, Feet 2 = 3, Inches 2 = 4.

  1. 01Start by noting the input — Feet 1: 5.
  2. 02Start by noting the input — Inches 1: 7.
  3. 03Start by noting the input — Feet 2: 3.
  4. 04Start by noting the input — Inches 2: 4.
  5. 05Substitute these values into the formula: {const t=12 × e.ft1+e.in1+(12 × e.ft2+e.in2),a=floor(t / 12),n=t%12;return"".concat(a,"' ").concat(n,'"')}
  6. 06Compute Total (ft’ in”): the calculator returns 8' 11".
  7. 07Cross-check the answer by opening the Derivation panel above — every line of math is shown so you can follow the computation end-to-end.
§04FAQ

Frequently asked questions

Yes. The calculator implements the standard formula as documented and returns exact floating-point results. No approximations are used unless noted in the formula.
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