How Many Wall Tiles Do I Need? Bathroom, Shower and Kitchen Wall Guide

To work out how many wall tiles you need, calculate the area that will actually be tiled, subtract large doors or windows, add an allowance for cuts and breakage, then divide the result by the coverage of one box. The final number of boxes should always be rounded up.

The basic method is the same for bathroom walls, shower enclosures and kitchen backsplashes, but the waste allowance may change depending on tile size, pattern, wall shape and the number of corners, niches or outlets.

What measurements do you need?

Before choosing a waste percentage or counting boxes, measure the surfaces that will be covered. Use metres and square metres, or feet and square feet, but do not mix the two systems in one calculation.

• The width of every wall section that will be tiled.
• The height of the tiled area, which may be the full wall height or only part of the wall.
• The width and height of large doors, windows or untiled openings.
• The tile size shown on the packaging.
• The area covered by one box.
• The planned tile pattern: straight, offset, diagonal, herringbone or another layout.
• The number of external corners, niches, shelves, sockets and pipe penetrations.

How to calculate wall tile area step by step

1. Calculate the area of each tiled wall

Multiply the width of a wall by the height that will be tiled. If several walls have different dimensions, calculate them separately and add the results together.

2. Add all tiled wall sections

For a bathroom, this may include four full walls. For a shower, it may include two or three walls. For a kitchen backsplash, it may include several narrow sections between the worktop and wall cabinets.

3. Subtract large untiled openings

Subtract the area of large doors, windows or clearly untiled sections. Small sockets, pipe holes and narrow gaps are usually not worth subtracting because tiles still need to be cut around them and the offcuts may not be reusable.

4. Add a waste allowance

The waste allowance covers edge cuts, corners, broken tiles, pattern alignment and pieces that cannot be reused elsewhere. A simple straight layout on regular walls may need less spare material than a diagonal or herringbone pattern.

5. Divide by the coverage per box

Manufacturers normally state how many square metres or square feet one box covers. Divide the adjusted tile area by this figure and round up. Do not round the area down before calculating boxes.

Bathroom wall tile example

Suppose a bathroom is 2.4 m long, 1.8 m wide and tiled to a height of 2.4 m. All four walls will be tiled, but there is one door and one window.

• Bathroom perimeter: (2.4 m + 1.8 m) × 2 = 8.4 m.
• Gross wall area: 8.4 m × 2.4 m = 20.16 m².
• Door area: 0.9 m × 2.0 m = 1.8 m².
• Window area: 0.6 m × 0.8 m = 0.48 m².
• Net tiled area: 20.16 − 1.8 − 0.48 = 17.88 m².
• Area with 10% waste: 17.88 × 1.10 = 19.668 m².

How many tiles do you need for shower walls?

A shower calculation should include every wall inside the wet area, the full planned tile height and any returns around an entrance. Niches and ledges can increase cutting even when their surface area is small.

How many tiles do you need for a kitchen backsplash?

A backsplash usually covers a smaller area than a bathroom, but it often contains more sockets, switches, corners and short tile runs. Because the total area is small, rounding to complete boxes can create a larger percentage of surplus.

1. Measure the length of each backsplash section.
2. Measure the height from the worktop to the wall cabinets or chosen finish line.
3. Calculate each rectangular section separately.
4. Subtract only large untiled areas.
5. Add waste for sockets, corners and pattern alignment.
6. Divide by the box coverage and round up.

How much extra tile should you allow?

There is no single waste percentage that suits every wall. The figures below are practical starting points rather than guaranteed values. Complex layouts should be checked against an actual tile plan.

Should you subtract doors, windows and cabinets?

Large openings should normally be subtracted because they can remove a significant amount of tiled area. Small obstacles often should not be deducted because the surrounding tiles still need to be purchased and cut.

Tile size, grout joints and layout

For purchasing, box coverage is usually more reliable than counting individual tiles. The packaging already states how much surface the tiles in one box can cover. Counting tiles can still be useful for planning rows, checking symmetry and deciding where cut pieces will appear.

A simple area calculation does not show whether a particular tile size fits the wall neatly. Two projects with the same wall area may require different quantities if one layout creates many narrow edge cuts or unusable offcuts.

• Large-format tiles may produce fewer grout lines but larger unusable offcuts.
• Small tiles or mosaics may be easier around curves and niches but are often sold by sheet coverage.
• Grout joint width affects the visual layout and row positions.
• Feature patterns may require tiles to be centred rather than started from one corner.
• Rectified tiles and handmade tiles can have different installation joint requirements.

Why tile batch numbers matter

Tiles from different production batches can vary slightly in shade, pattern or calibration. This is one reason to buy the full expected quantity at the same time instead of planning to purchase the final box later.

Check that the boxes have matching shade and calibre information where the manufacturer provides it. Before installation, open several boxes and mix tiles across them so that small natural variations are distributed over the wall.

Should you keep spare wall tiles?

Keeping a few unused tiles is useful for future repairs around plumbing, damaged corners or replaced fittings. The exact quantity depends on tile availability and project size, but several full tiles or a sealed spare box can be valuable when the design is discontinued.

Common wall tile calculation mistakes

• Using the full room floor area instead of measuring each tiled wall.
• Forgetting that some walls are tiled only part of the way up.
• Subtracting every socket and pipe hole from the wall area.
• Adding no waste because the total area already looks generous.
• Using the area of one tile but forgetting that tiles are purchased in boxes.
• Rounding the number of boxes down.
• Ignoring niches, external corners and boxed-in pipes.
• Assuming straight and herringbone layouts need the same quantity.
• Buying different batches because the original order was too small.
• Ordering before confirming the actual tile layout.

Wall tile order checklist

1. Measure every wall section twice.
2. Confirm the finished tile height.
3. Subtract only large untiled openings.
4. Check the tile orientation and pattern.
5. Choose a realistic waste allowance.
6. Read the coverage per box from the product label.
7. Round the box quantity up.
8. Check shade and calibre numbers before accepting the order.
9. Keep useful spare tiles for future repairs.
10. Confirm that the wall preparation, waterproofing and adhesive system suit the installation.

Frequently asked questions

How do I calculate how many wall tiles I need?

Multiply the width by the tiled height for each wall, add the wall areas, subtract large openings, add a waste allowance and divide by the coverage per box. Round the result up to a full box.

Is 10% extra tile enough?

Ten percent is a common starting point for a straight layout on regular walls. More may be needed for diagonal patterns, herringbone, niches, many corners or large tiles on small surfaces.

Do I subtract the bathroom door from the tile calculation?

A full-size bathroom door should normally be subtracted because it removes a substantial area. Do not subtract small sockets, switches or pipe openings individually.

How many spare tiles should I keep?

Keep at least several full tiles after installation. For a distinctive, limited or frequently changing product range, retaining a sealed spare box may make future repairs much easier.

Can floor tiles be used on walls?

Some floor tiles can be installed on walls, but their weight, size, substrate requirements and adhesive system must be checked. Confirm the product specification and installation method before ordering.

Does the calculator include adhesive and grout?

A wall tile area calculation estimates tiles and boxes. Adhesive and grout depend on tile dimensions, notch size, substrate condition, joint width, joint depth and manufacturer coverage data, so they should be calculated separately.

Related HomDera guides

Final calculation

The most reliable wall tile estimate starts with the actual tiled surfaces, not the room floor area. Measure each section, subtract only large openings, account for the chosen layout and use the coverage printed on the box.

The result remains an estimate until the tile layout is confirmed. For bathrooms, showers and complicated feature walls, checking the final quantity with the installer or supplier can prevent both a shortage and an unnecessary surplus.