Calculate Room Square Footage

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Room Square Footage Calculator

Accurately determine the floor area of any room for flooring, painting, or renovation projects. Enter your dimensions in feet and inches below.

Feet
Inches
Feet
Inches
0% (Exact Area) 5% (Simple Installation) 10% (Standard Recommendation) 15% (Diagonal / Complex Pattern) 20% (High Waste) Professionals recommend adding 10% for cuts and mistakes.
Net Area
0 sq ft
Total Materials Needed (incl. waste)
0 sq ft
(0 sq meters)

How to Calculate Room Square Footage

Calculating the square footage of a rectangular room is a fundamental skill for home improvement. The basic formula is Length × Width = Area. However, real-world rooms often involve partial inches and irregular shapes.

The Calculation Process

  1. Measure Length and Width: Use a tape measure to find the longest points of the room. Record both feet and inches.
  2. Convert to Decimals: To multiply easily, convert inches to decimal feet by dividing the inches by 12. (e.g., 6 inches = 0.5 feet).
  3. Multiply: Multiply the decimal length by the decimal width.
  4. Add Waste Factor: If you are buying flooring or tiles, add 10% to your total to account for cuts and corners.

Examples of Common Room Sizes

Room Type Dimensions Total Square Feet
Small Bathroom 5′ x 8′ 40 sq ft
Standard Bedroom 10′ x 12′ 120 sq ft
Master Bedroom 14′ x 16′ 224 sq ft
Standard 2-Car Garage 20′ x 20′ 400 sq ft

Measuring Irregular Rooms

If your room is L-shaped or has alcoves, do not try to calculate it as one large rectangle. Instead, divide the floor plan into smaller rectangles (Area A, Area B, Area C). Calculate the square footage for each rectangle separately and then add the totals together for your final measurement.

function calculateRoomArea() { // Get input values var lFt = document.getElementById("lenFt").value; var lIn = document.getElementById("lenIn").value; var wFt = document.getElementById("widFt").value; var wIn = document.getElementById("widIn").value; var wastePercent = document.getElementById("wasteFactor").value; // Basic validation if (lFt === "" || wFt === "") { alert("Please enter at least the feet for both length and width."); return; } // Convert to floats var lenFt = parseFloat(lFt) || 0; var lenIn = parseFloat(lIn) || 0; var widFt = parseFloat(widFt) || 0; var widIn = parseFloat(widIn) || 0; var wasteFactor = parseFloat(wastePercent) / 100; // Math logic var totalLength = lenFt + (lenIn / 12); var totalWidth = widFt + (widIn / 12); var netArea = totalLength * totalWidth; var totalWithWaste = netArea * (1 + wasteFactor); var areaMetric = totalWithWaste * 0.092903; // Display results document.getElementById("netResult").innerText = netArea.toFixed(2) + " sq ft"; document.getElementById("totalResult").innerText = totalWithWaste.toFixed(2) + " sq ft"; document.getElementById("metricResult").innerText = "(" + areaMetric.toFixed(2) + " sq meters)"; // Show the box document.getElementById("results-box").style.display = "block"; }

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