Build any floor plan or plot from simple shapes - rectangles, circles, triangles, trapezoids and ovals - add the parts, subtract the cut-outs, and get the total area in square metres, square feet, square yards and hectares.
Counts toward the total
Build any floor plan or lot from simple shapes. Switch a shape to Subtract - it turns red and is marked a cut-out - to remove a stair void, a kitchen island or anything the area wraps around, and use Quantity for repeated bays. The total is the added shapes minus the subtracted ones, shown in every common area unit.
Square feet
215 sq ft
Square yards
23.9 sq yd
Hectares
0.0020
Net area 20 m². Feed it into the tile, paint, flooring or carpet calculator to turn it into material.
Area is just length times width - but real rooms and lots are rarely one clean rectangle. The trick is to break the space into simple shapes, work out each one, and add them up. Anything that should not count - a stair void, a kitchen island, a pond the deck wraps around - is worked out the same way and subtracted:
rectangle = length × width
circle = π × (diameter ÷ 2)²
triangle = base × height ÷ 2
trapezoid = (side A + side B) ÷ 2 × gap
oval = π ÷ 4 × length × width
total = (sum of added shapes) − (sum of subtracted shapes)
Each shape can repeat with a quantity, so five identical alcoves are one row. The subtracted shapes come off the added ones, and the net total is held at zero - an over-large cut-out can never push the area below nothing. The answer is shown in every common unit at once, so the same measurement works whether you think in square feet, square metres, square yards or acres.
This example follows the unit system you pick in the calculator above.
An open living area: a 6 × 4 m main room, plus a triangular bay (3 m base, 2 m deep), minus a round kitchen island 2 m across:
Measure each piece, pick the matching shape, and the calculator applies the formula. The two main dimensions mean slightly different things per shape:
| Shape | What to measure | Area formula |
|---|---|---|
| Rectangle / square | Length and width | length × width |
| Circle | Diameter (straight across) | π × (diameter ÷ 2)² |
| Triangle | Base and perpendicular height | base × height ÷ 2 |
| Trapezoid | The two parallel sides and the gap between them | (side A + side B) ÷ 2 × gap |
| Oval / ellipse | The two full axes (length and width) | π ÷ 4 × length × width |
The calculator shows all of these together; this table is for quick mental checks.
| From | To | Multiply by |
|---|---|---|
| Square feet | Square metres | 0.0929 |
| Square metres | Square feet | 10.764 |
| Square feet | Square yards | ÷ 9 |
| Square metres | Square yards | 1.196 |
| Square feet | Acres | ÷ 43,560 |
| Square metres | Hectares | ÷ 10,000 |
| Square feet | Building “squares” | ÷ 100 |
This is the starting point - once you have the area, the material calculators take it from there:
In the United Kingdom, floor and room area is usually quoted in square metres (m²), and land in hectares, or acres on older land titles. Property is measured to the RICS Code of Measuring Practice and the International Property Measurement Standards, most often as gross internal area.
For the local measuring rules, see the RICS Code of Measuring Practice.
For a plain rectangular room, multiply the length by the width - a 4 m by 3 m room is 12 square metres. For a room that is not a simple rectangle, split it into rectangles, triangles and curved pieces, work out each one, and add them up. Enter each piece above and the calculator does the adding, and gives the same total in square feet, square yards and hectares.
Yes. In metric mode every measurement is a single metre box, so a 3.85 m wall goes straight in as 3.85 - enter the value just as you read it off the tape. Switch the toggle to imperial to enter feet and inches instead, in separate boxes. Whichever you pick, the answer is shown in square metres, square feet, square yards and hectares at once.
A hectare is 10,000 square metres, which is about 2.47 acres, 107,640 square feet or 11,960 square yards. Pictured as a square it is 100 m on each side, and it is a little larger than an international rugby pitch. Enter a plot above and the calculator shows its size in hectares alongside the square metres.
Break it into shapes that you can measure. An L-shaped room is two rectangles; a room with an angled wall is a rectangle plus a triangle; a bay window adds a trapezoid or part of a circle. Add each piece as its own shape above. Anything that should not count - a stair void, a kitchen island, a structural column - is added as a shape set to Subtract, so it comes off the total.
One square metre is about 10.76 square feet or 1.196 square yards. One square yard is 9 square feet, or about 0.836 square metres. So to go from square metres to square feet, multiply by 10.76; to square yards, multiply by 1.196. The calculator shows all of these at once, so you do not have to convert by hand.
A circle area is pi times the radius squared, where the radius is half the diameter. Measure straight across the widest point to get the diameter, pick the Circle shape and enter that one figure - the calculator squares the radius and multiplies by pi for you. For a half-round, work out the full circle and use a quantity of half, or split it off as its own shape.
It depends what the area is for. For flooring or tile you usually do subtract a fixed island or a column base, because you do not lay material under it - set that shape to Subtract. For paint you size off wall area, not floor area, so this tool feeds the wall calculators rather than replacing them. When in doubt, measure the gross area and the cut-outs separately so you can decide either way.
A "square" is a trade unit of about 9.29 square metres (100 square feet), used for whole-house size in Australia and New Zealand and for roofing and siding in North America. So a "30-square" home is about 279 m² (roughly 3,000 sq ft). This calculator works in square metres and square feet; to get squares, divide the square-metre figure by 9.29, or the square-foot figure by 100.
For buying materials, measure to the nearest couple of centimetres - small errors barely move the total, and the material calculators add a waste allowance on top. For a property listing or a planning submission, follow the local measuring standard - the RICS code in the UK, for example - because what counts as floor area is defined precisely and can change the figure.
The length-times-width method for rooms, walls and irregular shapes, with a room-size table.
Read guide→Measure a whole house room by room or from outside, and know what counts as living area.
Read guide→The square feet to square metres conversion both ways, with a ready-reckoner table.
Read guide→An acre is 43,560 sq ft - with a fractions-of-an-acre table and how big an acre really is.
Read guide→Square feet to square yards is a divide-by-9 - with a table and the carpet and concrete context.
Read guide→What 1,000 sq ft looks like - dimensions, metric size and everyday comparisons.
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