Square Footage Calculator

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square footage calculator
Rectangle / SquareCircleTriangle
Results:
function updateInputs(){var shape=document.getElementById('shape_type').value;var row2=document.getElementById('row2');var l1=document.getElementById('label1');var l2=document.getElementById('label2′);if(shape==='rectangle'){row2.style.display='table-row';l1.innerHTML='Length (ft):';l2.innerHTML='Width (ft):';}else if(shape==='circle'){row2.style.display='none';l1.innerHTML='Radius (ft):';}else if(shape==='triangle'){row2.style.display='table-row';l1.innerHTML='Base (ft):';l2.innerHTML='Height (ft):';}}function calculateSqFt(){var shape=document.getElementById('shape_type').value;var v1=parseFloat(document.getElementById('input1').value);var v2=parseFloat(document.getElementById('input2').value);var price=parseFloat(document.getElementById('inputPrice').value)||0;var waste=parseFloat(document.getElementById('inputWaste').value)||0;var showSteps=document.getElementById('steps').checked;if(isNaN(v1)||(shape!=='circle'&&isNaN(v2))){alert('Please enter valid numerical dimensions.');return;}var area=0;var formulaText=";if(shape==='rectangle'){area=v1*v2;formulaText='Area = Length × Width = '+v1+' × '+v2;}else if(shape==='circle'){area=Math.PI*Math.pow(v1,2);formulaText='Area = π × r² = 3.14159 × '+v1+'²';}else if(shape==='triangle'){area=0.5*v1*v2;formulaText='Area = ½ × Base × Height = 0.5 × '+v1+' × '+v2;}var wasteAmount=area*(waste/100);var totalArea=area+wasteAmount;var totalCost=totalArea*price;var resultHTML='
Total Area: '+totalArea.toFixed(2)+' sq ft
';resultHTML+='Base Area: '+area.toFixed(2)+' sq ft
';if(waste>0){resultHTML+='Waste ('+waste+'%): '+wasteAmount.toFixed(2)+' sq ft
';}if(price>0){resultHTML+='Estimated Total Cost: $'+totalCost.toLocaleString(undefined,{minimumFractionDigits:2,maximumFractionDigits:2});}document.getElementById('answer').innerHTML=resultHTML;if(showSteps){var stepsHTML='Calculation Steps:
1. '+formulaText+' = '+area.toFixed(4)+' sq ft
';if(waste>0){stepsHTML+='2. Waste = '+area.toFixed(2)+' × ('+waste+'/100) = '+wasteAmount.toFixed(2)+' sq ft
';stepsHTML+='3. Total = '+area.toFixed(2)+' + '+wasteAmount.toFixed(2)+' = '+totalArea.toFixed(2)+' sq ft
';}if(price>0){stepsHTML+='4. Cost = '+totalArea.toFixed(2)+' sq ft × $'+price.toFixed(2)+' = $'+totalCost.toFixed(2);}document.getElementById('stepDetails').innerHTML=stepsHTML;document.getElementById('stepDetails').style.display='block';}else{document.getElementById('stepDetails').style.display='none';}document.getElementById('calculatorAnswer').style.display='block';}function resetCalc(){document.getElementById('calculatorAnswer').style.display='none';document.getElementById('stepDetails').style.display='none';}

How to Use the Square Footage Calculator

A square footage calculator is an essential tool for homeowners, contractors, and real estate professionals. Whether you are ordering new hardwood flooring, painting a room, or measuring a lot for landscaping, knowing the exact surface area ensures you purchase the correct amount of materials and avoid costly overages or delays.

To get started, select the shape of the area you are measuring and enter the dimensions in feet. Our calculator handles the math for you, including complex shapes like circles and triangles.

Shape Selection
Choose between Rectangle, Circle, or Triangle based on the layout of your space.
Dimensions (ft)
Enter the measurements in feet. If you have measurements in inches, divide them by 12 first (e.g., 6 inches = 0.5 feet).
Waste Factor
Most pros recommend adding 5-10% to account for cuts, breakage, or mistakes during installation.

The Square Footage Formulas

When using a square footage calculator, it helps to understand the underlying geometry. Depending on the shape of your room or project area, different mathematical formulas apply:

Rectangle/Square: Length × Width = Area

Circle: π (3.14159) × Radius² = Area

Triangle: ½ × Base × Height = Area

  • Length/Base: The longest horizontal distance.
  • Width/Height: The distance perpendicular to the length/base.
  • Radius: The distance from the center of a circle to its outer edge.

Practical Calculation Example

Scenario: You are installing tile in a rectangular kitchen that measures 15 feet long and 12 feet wide. The tile costs $5.50 per square foot, and you want to include a 10% waste factor for diagonal cuts.

Step-by-step solution:

  1. Find Base Area: 15 ft × 12 ft = 180 sq ft
  2. Calculate Waste: 180 × 0.10 = 18 sq ft
  3. Total Square Footage: 180 + 18 = 198 sq ft
  4. Calculate Cost: 198 sq ft × $5.50 = $1,089.00

Common Questions (FAQ)

How do I calculate square footage if my room is L-shaped?

For irregular or L-shaped rooms, divide the space into two or more simple rectangles. Calculate the square footage of each rectangle separately using the square footage calculator, then add the results together for the total area.

How do I convert square inches to square feet?

Since there are 144 square inches in a square foot (12″ × 12″), you must divide your total square inches by 144 to get the square footage. For example, 1,440 sq. in. ÷ 144 = 10 sq. ft.

What is a standard waste factor for flooring?

For standard layouts (straight planks or tiles), 5% to 10% is typical. For complex patterns like herringbone or rooms with many alcoves, 15% is safer to ensure you don't run out of material.

Tips for Accurate Measuring

To get the most out of our square footage calculator, follow these professional tips:

  • Measure twice to verify your numbers. Even a 6-inch mistake can significantly change your material order.
  • Measure into doorways and closets if you plan to run the same flooring through them.
  • Subtract "islands" or permanent fixtures (like a kitchen island or a built-in tub) from your total if you won't be covering that area.
  • Always round up to the nearest inch when taking initial measurements.

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