Calculate Square Footage of a Room

Square Footage Calculator

Calculation Results

Standard Square Footage: 0 sq ft

With 10% Waste Factor: 0 sq ft

Estimated Material Cost: $0.00

function calculateSquareFootage() { var lenFt = parseFloat(document.getElementById('room_length_ft').value) || 0; var lenIn = parseFloat(document.getElementById('room_length_in').value) || 0; var widFt = parseFloat(document.getElementById('room_width_ft').value) || 0; var widIn = parseFloat(document.getElementById('room_width_in').value) || 0; var price = parseFloat(document.getElementById('price_per_sqft').value) || 0; // Convert everything to total feet var totalLength = lenFt + (lenIn / 12); var totalWidth = widFt + (widIn / 12); if (totalLength <= 0 || totalWidth 0) { document.getElementById('total_cost').innerText = "$" + totalCost.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); document.getElementById('cost_row').style.display = 'flex'; } else { document.getElementById('cost_row').style.display = 'none'; } document.getElementById('sqft-results').style.display = 'block'; }

How to Calculate Square Footage

Calculating the square footage of a room is an essential step for DIY projects like installing new flooring, painting walls, or purchasing area rugs. The basic formula is straightforward: Length × Width = Area. However, real-world rooms often involve inches, irregular shapes, and the need for extra materials.

The Basic Calculation Method

To find the square footage manually, measure the two longest sides of the room. If your measurements include inches, convert them to decimals by dividing the inches by 12. For example, if a wall is 10 feet 6 inches, you calculate 6 ÷ 12 = 0.5, making the length 10.5 feet.

• Step 1: Measure the length in feet and inches.
• Step 2: Measure the width in feet and inches.
• Step 3: Multiply the decimal length by the decimal width.

Why Add a 10% Waste Factor?

Experienced contractors always recommend purchasing 10% more material than the actual square footage calculated. This is known as the "waste factor." This extra material accounts for:

• Cuts and Snaps: Hardwood or tile needs to be cut to fit edges.
• Breakage: Materials can break during transport or installation.
• Pattern Matching: Some designs require more material to align patterns correctly.
• Future Repairs: Having a few spare planks or tiles ensures you can fix damage years later with the same dye lot.

Handling Irregular Rooms

If your room is L-shaped or has alcoves, do not try to measure it as one giant block. Instead, divide the room into smaller rectangles or squares. Calculate the square footage for each individual section and then add those totals together for the final sum.

Pro Tip: When measuring for paint, subtract the square footage of large windows and doors (usually about 15-20 sq ft each) from your total wall area to get a more accurate estimate of how many gallons of paint you need.