Area Calculator: Free Online Area Measurement Tool
Use our free area calculator to measure square footage, square meters, and acres from a simple length and width. Built for flooring, landscaping, real estate, and construction projects, it takes your measured dimensions and instantly returns the area in all three units so you can compare against material coverage rates or lot listings without doing the conversion math yourself.
How to use this calculator.
- Measure your space. Use a tape measure or plans to get the length and width of the area in feet.
- Enter the length. Input the longer dimension of the area.
- Enter the width. Input the shorter dimension.
- Review your results. The calculator displays area in square feet, square meters, and acres instantly.
- Break up irregular shapes first. For L-shaped or multi-section areas, split the space into rectangles, run each through the calculator separately, and add the totals together.
How do you calculate area measurements?
For any rectangular area, multiply length by width to get square feet, then apply a fixed conversion factor to reach square meters or acres.
Area (sq ft) = Length (ft) × Width (ft)
Area (m²) = Area (sq ft) × 0.092903
Area (acres) = Area (sq ft) ÷ 43,560
Where:
- Length: The longer dimension of the area, in feet.
- Width: The shorter dimension of the area, in feet.
- 0.092903: The squared conversion factor between feet and meters (0.3048²), used because area is a two-dimensional measurement.
- 43,560: The number of square feet in one acre, the standard US land measurement unit.
Example calculation.
Let's calculate the area of a rectangular building lot.
Scenario: A lot measures 100 ft long by 60 ft wide.
- Calculate square feet: 100 ft × 60 ft = 6,000 sq ft
- Convert to square meters: 6,000 × 0.092903 = 557.42 m²
- Convert to acres: 6,000 ÷ 43,560 = 0.1377 acres
Result: The lot measures 6,000 sq ft, equivalent to 557.42 m² or 0.1377 acres.
Tips from the field.
- Always add 5-10% for waste. When ordering flooring, tile, or landscaping materials, overage accounts for cuts and irregular edges.
- Break irregular shapes into rectangles. Calculate each section separately, then sum the totals rather than trying to force one formula onto the whole footprint.
- One acre equals 43,560 sq ft. A typical suburban lot is about 0.25 acres (10,890 sq ft), which is a useful benchmark when comparing property listings.
- Divide square feet by 9 for square yards. Carpet and some flooring materials are priced by the square yard, not the square foot.
- Use survey figures for legal purposes. A tape-measure or calculator estimate is fine for materials and planning, but deeds and property lines should reference an official survey.
- Double-check odd-shaped rooms before ordering. Bay windows, closets, and jogs in a wall can throw off a quick length-times-width estimate. Measure the largest rectangle first, then add or subtract the smaller sections.
Disclaimer: This calculator provides estimates for planning purposes only. Actual area may vary based on measurement accuracy, irregular boundaries, and rounding. For legal property descriptions or official land records, consult a licensed surveyor. PavementCalculator.com assumes no liability for material overages or shortages resulting from these estimates.
Cost, price, and density figures on this page reflect approximate U.S. averages as of August 2026 and vary by region, supplier, and material availability.
Frequently asked questions.
How do I calculate the area of a room?
Multiply length × width in feet to get square footage. For a 12×15 ft room: 12 × 15 = 180 sq ft. For irregular rooms, break into rectangles, calculate each, and sum. Use our calculator above: enter dimensions for instant results.
How do I convert square feet to acres?
Divide square feet by 43,560. For example, 87,120 sq ft ÷ 43,560 = 2 acres. One acre is approximately 208.7 ft × 208.7 ft.
How many square feet are in an acre?
One acre equals 43,560 square feet. A typical suburban lot is 0.25 acres (10,890 sq ft). A football field (including end zones) is about 1.32 acres (57,600 sq ft).
How do I calculate area for a triangle?
Area = (base × height) ÷ 2. For a triangular garden bed with 20 ft base and 8 ft height: (20 × 8) ÷ 2 = 80 sq ft. For other shapes, break the area into rectangles and triangles.
How do I calculate area for a circle?
Area = π × radius². For a circular patio with 10 ft diameter (5 ft radius): π × 5² = 78.5 sq ft. Use 3.1416 for π. Our calculator handles rectangular areas: for circles, calculate radius × radius × 3.1416 separately.