Structure and measuring calculators
Five calculators that start with geometry: the area of a room, the face of a wall, the rise of a stair, and the pitch and area of a roof.
Last updated: September 29, 2026
In this section
- Room areaCalculate the floor area of a rectangular, L-shaped or irregular room in square metres and square feet, with the perimeter for skirting and trim.
- BrickCalculate how many bricks a wall needs from its size, the brick size and the mortar joint, with a breakage allowance and the volume of mortar in the joints.
- StairsRisers, treads, total run and a stringer layout to 1/16 in or 1 mm, with the first-riser cut, a throat check for 2×12 or 2×10 and landings when needed.
- RoofingCalculate the area of a pitched roof from its footprint and pitch, and the number of bundles of shingles to buy, with an allowance for waste.
- Roof pitchConvert roof pitch between rise and run, inches per 12, degrees and percent, get the pitch multiplier and a pitch chart, and learn how to measure it.
Start with the area
Most material is bought by area. The room area calculator handles rectangles, L-shaped rooms and rooms that you measure as several rectangles, and it shows the result in square metres and square feet at the same time.
You can then enter that area in the tile and flooring calculators.
Quantities are not design
Stairs, roofs and brick walls are regulated by building codes, and the rules differ between countries, states and provinces. The calculators on this site count material and show dimensions. They do not check your project against a code.
Before you build, confirm the limits that apply to you with your local building authority or with a qualified professional.
Frequently asked questions
- How do I measure a room that is not a rectangle?
- Divide the floor into rectangles, measure the length and width of each one, and add the areas. The room area calculator does this for up to four rectangles. For an L-shaped room you can also enter the full length and width and the size of the missing corner.
- Does the stair calculator follow my building code?
- Only as far as you tell it. You enter the highest riser that your code allows and the tread depth you want, and the calculator divides the total rise into equal risers that stay within your limit. Other rules, such as headroom, width, handrails and landings, are not checked.
- Why is the roof area larger than the area of the house?
- A sloping roof covers more surface than the ground below it. The roofing calculator multiplies the area seen from above by a factor that depends on the pitch: 1 divided by the cosine of the pitch angle. The roof pitch calculator converts a pitch such as 6/12 into degrees and gives that factor.
- How many bricks are in a square metre of wall?
- It depends on the size of the brick and of the mortar joint. A brick of 215 by 65 millimetres with 10 millimetre joints takes up 225 by 75 millimetres of wall, which gives about 59.3 bricks for each square metre of a wall that is one brick-width thick.