Square Footage Calculator: Rooms, Total Area and Cost

Calculate your quantities

Enter your measurements below. Change the example allowance, product information and price to match your project.

Enter measurements and select Calculate.

Prices use your chosen currency. A zero price leaves cost at zero. Material estimates exclude labor, tax, delivery and accessories. Enter decimal feet, not feet-and-inches notation. Decimal point or comma accepted; omit thousands separators.

How to use this square footage calculator

Split an L-shaped room into two non-overlapping rectangles. Enter decimal feet: 10 ft 6 in = 10.5 ft, not 10.6. This is a measured area estimate, not a legal or appraisal definition of living area.

Measure the relevant area or volume using the units shown beside each input.
Replace example product values with the supplier's yield, coverage, density or pack quantity where applicable.
Set the extra allowance explicitly. Enter zero when you want the geometric quantity without an allowance.
Select Calculate, then compare the unrounded purchasing basis with whole bags, boxes or packs where displayed.

Formula

Net ft² = first length × width + second length × width − deductions. Material area = net area × (1 + extra / 100). m² = ft² × 0.09290304.

Worked example

A 10 × 10 ft room plus an 8 × 5 ft alcove totals 140 ft². Subtract 10 ft² for an excluded area to get 130 ft²; adding 10% yields 143 ft² of material.

Six calculated examples

Only the first length changes in this table. All other inputs use the calculator's reset values shown above. These are mathematical scenarios, not measured supplier quotes.

square footage quantity examples
First length	Calculated quantities
5 ft	Net area (ft²): 50; Net area (m²): 4.645; Material area (ft²): 55
8 ft	Net area (ft²): 80; Net area (m²): 7.432; Material area (ft²): 88
10 ft	Net area (ft²): 100; Net area (m²): 9.29; Material area (ft²): 110
12 ft	Net area (ft²): 120; Net area (m²): 11.148; Material area (ft²): 132
15 ft	Net area (ft²): 150; Net area (m²): 13.935; Material area (ft²): 165
20 ft	Net area (ft²): 200; Net area (m²): 18.581; Material area (ft²): 220

Frequently asked questions

Can I add more rooms?

Calculate groups separately and add their net areas. Avoid overlapping rectangles.

Are square feet and feet interchangeable?

No. Feet measure length; square feet measure area.

Does extra material increase my room area?

No. Net area stays unchanged; the allowance changes only estimated material quantity.

Units and calculation limits

One foot is 0.3048 meters; one cubic yard is 27 cubic feet. Calculations retain precision until display; whole-package quantities are rounded up. Outputs estimate quantities from your measurements and assumptions. Confirm product coverage and units before ordering.

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