How to Figure Out How Many Tiles You Need

Working out how many tiles to buy can feel a bit stressful the first time. You don’t want to under-order and get stuck halfway through, but you also don’t want ten boxes left over at the end. The good news is a tape measure, and a calculator will do the job.

Step 1: Measure the floor

If the room is a simple rectangle or square:

Measure the length
Measure the width
Multiply them together

So, a room 5m long and 4m wide = 20sqm. Easy.

If the room is shaped differently (like an L or has a nook), just break it into smaller rectangles, measure those and add them all up.

Step 2: Measuring walls (if you're tiling them)

Walls are basically the same formula.

Measure the height (or the height to where you want to tile to)
Measure the width
Multiply them together

If you’ve got more than one wall, do them one by one and then add them together.

Tip: Don’t forget to take out windows and doors. Example:

Wall = 2.5m high × 3m wide = 7.5sqm
Window = 1m × 1.5m = 1.5sqm
So you only need to tile 6sqm.

Step 3: Add some extra (wastage)

Tiles aren’t like paint, you can’t use up every last bit. You’ll cut some, break some, and sometimes need extra to match a pattern. The safe bet is to add 15% more. If you’re laying something tricky like herringbone, bump that up to 20%.

Example: Room is 20sqm. Add 15% → 20 × 1.15 = 23sqm needed.

If you're using more than one tile

Keep the maths separate. Floor tiles in one column, wall tiles in another. Add 15% on each. That way you won’t accidentally short one style and over-order another.

An example of a bathroom

Floor = 20sqm
Walls to 1m high = 17.1sqm (after subtracting door etc)
So floor tile total = 37.1sqm → with wastage = 42.7sqm
Upper walls = 22.8sqm (after subtracting window etc)
With wastage = 26.2sqm

And remember: tiles are sold in boxes, so round up to the nearest box.

Elise Pride

eCommerce Manager

05 November 2025

Elise is a design-focused content creator at The Blue Space, offering practical renovation advice and trend-led insights to help customers style their dream spaces with confidence.