Understanding your result
Base area multiplies length by width and quantity. The allowance increases that base by the selected percentage, then the result is converted to the alternate area unit.
For flooring, the Tile Calculator converts surface area into tile and box quantities using tile dimensions and waste allowance.
For walls, the Paint Calculator accounts for openings, coats, and the product’s coverage rate.
The formula
Area units are squared. One square metre equals approximately 10.7639 square feet; it is not converted with the linear metre-to-foot factor.
Two 12 ft by 10 ft rooms
Each room is 120 ft², so two rooms total 240 ft². A 10% allowance adds 24 ft² for a planning total of 264 ft².
How to use this calculator
- Choose feet or metres and enter the rectangle dimensions.
- Enter how many equal areas you have and any extra allowance.
- Calculate the base, added, and converted areas.
Split irregular plans into rectangles
Measure each rectangle separately when a floor, wall, or yard is not one simple shape. Add the section areas for the complete total.
The quantity field is convenient only when the rectangles have identical dimensions.
Choose allowance for the material
Cutting loss and breakage differ by product, layout, and room shape. The editable percentage is a planning input rather than a universal rule.
For products sold by boxes or containers, use the dedicated tile or paint calculator to include package rounding.
Assumptions & limitations
What this calculation assumes
- Every repeated area has the same length and width.
- The surface is a flat rectangle.
- The allowance is applied after multiplying all equal areas.
What to keep in mind
- Curves, triangles, and cutouts are not modeled.
- Measurements and allowance determine the estimate accuracy.
- Supplier package sizes are not included.
Common questions
How do I calculate several different rooms?
Calculate each distinct rectangle separately, then add their base or adjusted areas.
Why is the conversion factor squared?
Area has two dimensions, so both length and width must be converted.
Should I always add 10%?
No. Choose an allowance based on the material, layout, cuts, and supplier guidance.