Room Size Calculator
Enter the room's length, width and ceiling height, and how many doors and windows it has. You get floor and wall area, volume, the paint and flooring to buy and the skirting length.
- Feet or metres
- Paint and flooring
- Doors and windows removed
For rectangular rooms. Split an L-shaped room into two rectangles and add the results.
One set of measurements answers most decorating questions. Floor area tells you how much carpet or tile to buy. Wall area, less doors and windows, gives the paint. Volume is what heaters, air conditioners and dehumidifiers are sized by. The perimeter, less door openings, is your skirting board.
Typical room sizes
Common rooms in homes in the UK and US. Search by room type or size.
| Room | Size (m) | Area (m²) | Size (ft) | Area (sq ft) |
|---|---|---|---|---|
| Single bedroom | 2.4 × 3.0 | 7.2 | 8 × 10 | 77 |
| Double bedroom | 3.0 × 3.6 | 10.8 | 10 × 12 | 116 |
| Main bedroom | 3.6 × 4.2 | 15.1 | 12 × 14 | 163 |
| Bathroom | 2.0 × 2.5 | 5 | 7 × 8 | 54 |
| Kitchen | 3.0 × 4.0 | 12 | 10 × 13 | 129 |
| Living room | 4.0 × 5.0 | 20 | 13 × 16 | 215 |
| Home office | 2.7 × 3.0 | 8.1 | 9 × 10 | 87 |
| Garage, single | 3.0 × 6.0 | 18 | 10 × 20 | 194 |
Room sizes vary a lot by age of the house. Victorian bedrooms are often larger than new-build ones, while open-plan living spaces in new homes can be bigger than any older room.
Room length and wall area
A room 3.5 m wide with a 2.4 m ceiling. Slide the length.
Wall area grows more slowly than floor area as rooms get bigger. A small room uses more paint per square metre of floor than a large one.
How to measure a room
A tape or laser measure and a notepad. Follow these steps.
Measure the length
Along the longest wall, skirting to skirting.
Measure at floor level and again at waist height. Old walls are rarely straight, and using the larger figure means you will not run short.
Metres or feet
Both work. Stick to one. Pick a unit system.
Used for building plans and materials in most countries. Paint tins list coverage in square metres.
Used for room sizes in the US and in UK estate agent listings.
Most mistakes come from mixing units. If your tape shows both, choose one and use it for every measurement.
Before buying materials
Order once, not twice. Tick each item.
Tick each item as you go.
Buy flooring and tiles from the same batch, as colour can vary slightly between production runs.
Everything from one measurement
Six answers for planning a room. Each tile explains one result.
For carpet, flooring, rugs and underlay.
Less doors and windows, for paint and wallpaper.
For heating, cooling and ventilation.
Litres and gallons for two coats.
Perimeter less door openings.
Use the volume figure when sizing heaters, air conditioners and dehumidifiers. Those calculators on this site take it directly.
Frequently Asked Questions
No question matches that search.
How do I calculate the square footage of a room?
Multiply the length by the width in feet. A room 12 by 14 feet is 168 square feet.
How do I calculate wall area for painting?
Add the lengths of all walls and multiply by the height. Subtract about 1.9 m² per door and 1.5 m² per window.
How much paint do I need for a room?
About 1 litre per 11 m² per coat. A typical 4.5 × 3.6 m bedroom needs about 7 litres for two coats on the walls.
How much extra flooring should I buy?
10% for straight lay boards and tiles, 15% for diagonal or herringbone patterns.
How do I measure an L-shaped room?
Split it into two rectangles, measure each and add the areas.
What is the average bedroom size?
About 11 m² (120 sq ft) for a double bedroom.
How do I convert square metres to square feet?
Multiply by 10.764. 15 m² is about 161 sq ft.
Measure once, plan everything
Take the length, width and height, count the doors and windows and let the calculator do the rest. You will have the floor, wall and volume figures for every job from painting to heating.
More size calculators
Each one has its own calculator, worked examples and answers to common questions.