Measure the length and width of the space in feet
Multiply length × width to get square footage (for rectangles)
For multiple rooms, calculate each room’s square footage separately and add them together
For irregular shapes, split the area into rectangles or triangles, calculate each part, then add the results
For a triangle, calculate square footage as (base × height) ÷ 2
For a circle, calculate square footage as π × (radius × radius)
For an area with semicircles, add the rectangle area plus the semicircle area (semicircle = (π × r²) ÷ 2)
If measurements are in inches, convert to feet by dividing by 12 before calculating
If measurements are in meters, convert to feet by multiplying by 3.28084 before calculating
Round square footage to the nearest whole number or to your preferred precision
If you have a plan or drawing, use the scale to convert dimensions to real feet, then calculate as above