Square meter calculator
Room area in square meters, from a tape reading in m and cm.
By Rohit GaurLast updated October 30, 2026Report a mistake
A tape reading good to 10 mm either way makes a 4 × 3 m room anything from 11.93 to 12.07 m². Set what your measurements are good to and the total says so — and the estimators order for the top of the range, because ordering for the middle is ordering too little half the time.
Bigger boxes, Enter for the next measurement, and the screen kept awake — for measuring with a tape or a laser meter in hand.
Rooms
Cutouts (taken off)
Photo notes
Extra areas (added on)
A cutout's area comes off the room. Draw one in the floor plan editor and it keeps its place as well.
Show how this was worked out
Room 1
3.6 × 3.6 = 12.96 m²
1 room counted: 12.96 m²
Waste and cost
- Area to buy
- 14.26 m²
Add a price to see the cost.
Materials only — labour, delivery and fittings are not included.
Make a quote for a client
Check a quote
Work the whole house out to the ANSI Z765 standard, with these rooms
Share this calculation
The link holds the measurements themselves, so it opens the same calculation on any device.
Recent calculations
Calculations you make are listed here, on this device only.
A room’s area in square meters is its length times its width, both in meters: a room 4 m long and
3 m wide is 4 × 3 = 12 m². Type the two sides above as your tape reads them — 3,5 and 3.5
both work, and 350 cm or 2 m 40 cm are understood too — and the result appears with square
feet beside it, 129.17 sq ft for that room.
Formulas for other shapes
| Shape | Area in m² | Example |
|---|---|---|
| Rectangle | length × width | 4 × 3 m = 12 m² |
| L-shape | split into two rectangles, add | 4 × 3 + 2 × 1.5 = 15 m² |
| Triangle | base × height ÷ 2 | 3 × 2 ÷ 2 = 3 m² |
| Circle | 3.1416 × radius × radius | radius 1.5 m: 7.07 m² |
| Room with a chimney box | whole rectangle − the box | 12 − 0.6 × 0.4 = 11.76 m² |
The calculator draws each of these to scale, so a side typed wrong shows up as a shape that looks wrong. The how to calculate square footage guide walks through every shape step by step; the method is the same in meters.
The centimeter trap
Most mistakes in metric area come from mixing units, not from the multiplication. 350 cm × 280 cm
is 98,000 square centimeters, which is 9.8 m², not 98: there are 10,000 cm² in a square meter, not 100. Give both sides in the same unit, or let the calculator read 350 cm for you and do the
conversion.
Round only at the end. Three rooms of 12.54 m² rounded down to 12 m² each lose 1.62 m² between them — about a box of flooring.
Why a listing’s figure may not match your tape
A floor area on a property listing is often measured to a different line than your tape. In the United Kingdom, a home’s energy performance certificate gives its total floor area, which counts the whole dwelling rather than the rooms one by one; in Australia builders still quote houses in “squares” of 100 sq ft, or 9.29 m² (Henley). Measure room by room and the total usually comes in under the listed figure, because walls and hallways are not in it.
What people use it for
- Flooring and tile, which are sold per square meter across Europe, Australia and most of Asia — add about 10% for cuts before you buy.
- Paint, where coverage is quoted in square meters per liter.
- Checking a listing against what you measure, room by room.
Already have a figure in square feet? Convert square feet to square meters instead. Switching the unit at the top of the calculator converts what you have typed rather than resetting it.