How do you add feet and inches together?

Convert everything to inches, add, then convert back — or skip the busywork entirely. 7′ 4¼″ + 3′ 9⅝″ is 11′ 1⅞″, and the feet-inch calculator produces that directly from the tape-measure reading, fractions and all.

How do I convert feet and inches to decimal feet?

Divide the inches by 12 and add to the feet: 8′ 6″ is 8.5 feet, and 10′ 3″ is 10.25 feet. Decimal feet are what most material formulas expect — the calculator shows both formats for every result.

Can the calculator solve equations?

Yes. Enter a linear equation like 2x + 3 = 7 and it solves for the unknown. It is built for the moments when a plan gives you a relationship between dimensions instead of the dimension itself.

Is the MatCalc360 calculator free?

Completely free — no login, no signup, no paywall. The same is true of every tool on MatCalc360, from the roofing calculator to the unit converter.

Engineer reviewing calculations on a tablet at a job site

MC360 // Tools & Converters

THE CALCULATOR THATSPEAKS FEETAND INCHES.

7′ 4¼″ plus 3′ 9⅝″ — construction math breaks normal calculators. This one handles feet, inches and fractions natively, with scientific functions and equation solving when the takeoff gets exotic. Free, no login.

Try the Calculator See how it works

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The Instrument

The Feet & Inches Calculator, up close

MC360 // feet-inch-calculatorLive in app

Inputs

Entry7′ 4¼″ + 3′ 9⅝″

ModeFeet-Inch

FunctionScientific

Equation2x + 3 = 7

Outputs

Result11′ 1⅞″

Decimal11.156 ft

Equationx = 2

Modes3 in 1

Opens the live calculator on matcalc360.pro

Run your own numbers

Process

Three steps. Zero guesswork.

Enter your measurements

Length, width, depth, pitch — the numbers you already pace off on site. No blueprints, no signup, no spreadsheet.

Calculate materials

The calculator applies the right formulas, density factors and waste allowances for your specific material.

Get your results

Squares, yards, tons, boards or sheets — a clean order list you can hand straight to the supplier.

Field Guide

CONSTRUCTION MATH WITHOUT THE HEADACHE

CH.01

Feet-inch-fraction is the native language

Standard calculators force you to convert everything to decimals and back — and that is where quarter-inch errors sneak into a cut list. This calculator accepts 7′ 4¼″ directly, adds it to 3′ 9⅝″, and answers 11′ 1⅞″ without a single manual conversion.

Type measurements as you read the tape
Fractions stay fractions — no decimal drift
Add, subtract, multiply, divide

CH.02

Scientific functions on standby

Trigonometry for roof angles, square roots for diagonal bracing, powers for volume work — the scientific mode covers the math behind stair layouts, rafter cuts and slope conversions without reaching for a second app.

Trig for rafter and stair angles
Square roots for diagonals
Powers and roots built in

CH.03

Equation solving when the plan is vague

When the drawing gives you a relationship instead of a number — 2x + 3 = 7 — the equation solver isolates the unknown directly. Solve for the missing dimension, the pitch variable or the spacing value right where you are standing.