Quick Calculators · Free to use
Square Footage & Area Calculator
Add rectangular sections, then subtract any openings or excluded areas.
Your estimate
Enter your measurements to see the estimate.
Net total area
sq ft- Gross rectangular area
- sq ft
- Area deducted
- sq ft
- Rectangular sections
- sections
Each rectangle contributes length × width. Overlapping sections would be counted twice.
Rectangles only, up to 50 sections. Divide irregular spaces into non-overlapping rectangles and enter deductions separately. No blueprint takeoff, slope correction, or automatic opening measurement is included.
How to Use This Calculator
Add rectangular sections, then subtract any openings or excluded areas.
Decimals and fractions accepted for dimensions. Unmarked values use the labeled unit; explicit feet/inches are converted. For example, 10' 6 1/4" is an explicit length; 10.6 means 10.6 of the labeled unit. Rates, prices, counts and areas use numbers only.
Inputs and where to find them
Length (ft). Measure one side of a rectangular section in feet. Add another rectangle for each separate part of an irregular area, taking care not to count overlapping sections twice. Fractional dimensions can be entered directly.
Width (ft). Measure the other side of the same rectangle, perpendicular to its length. Each added rectangle has its own length and width. Sloped surfaces should be measured on their actual surface if that is the area you need.
Openings / deductions (sq ft). Enter the combined square-foot area of openings or other portions to remove from the total. This field needs area, not a length. Leave it blank if the rectangles already exclude those portions; deductions cannot exceed their combined area.
Results, example and assumptions
Gross area is the sum of the active rectangles. Deducted area is the single exclusion total you entered, and net area is what remains. The rectangle count helps confirm how many sections were included. The result measures area only and does not add material waste or convert a plan footprint into sloped surface area.
Each section area = length (ft) × width (ft).
Gross area = sum of all section areas.
Net area = gross area − openings/deductions (sq ft).
Worked example: A 12 × 10 ft section is 120 sq ft and a 6 × 4 ft section is 24 sq ft. Together they are 144 sq ft. Subtracting 12 sq ft gives 132 sq ft net.
Rectangles only, up to 50 sections. Divide irregular spaces into non-overlapping rectangles and enter deductions separately. No blueprint takeoff, slope correction, or automatic opening measurement is included.