How Many Tiles Do You Need? The Easy Calculator Guide
📅 March 2026
⏱ 6 min read
🏷 Buyer’s Guide, Tiles
Ordering too few tiles means delays and batch-matching headaches. Ordering too many wastes money. Here’s how to calculate the exact amount you need — with ready-reference tables for typical Irish bathrooms and kitchens.
Working out how many tiles you need sounds like it should be straightforward — and it mostly is, once you know the method. But small mistakes in measurement or forgetting to account for waste can leave you short mid-project (expensive and stressful) or with boxes of surplus tiles gathering dust in the garage.
This guide gives you the simple formula, the waste allowances for different patterns, and ready-reference tables for the most common Irish bathroom and kitchen sizes. Bookmark it for when you’re ready to order.
The Basic Formula
Every tile calculation comes down to three steps:
Measure each surface.
For floors: length × width. For walls: length × height. Measure in metres for the simplest calculation.
Add all surfaces together.
Total up every floor and wall area you want to tile. Subtract windows and doors (a standard door is roughly 1.8m²; a standard window is about 0.5m²).
Add your waste allowance.
Multiply the total by 1.10 (for 10% waste) or 1.15 (for 15% waste on complex patterns). This is the number of m² you need to order.
Total m² needed = (Sum of all surfaces − doors/windows) × 1.10
Use × 1.15 for herringbone, diagonal, or rooms with many corners
That’s it. The rest of this guide applies that formula to real Irish rooms so you can skip straight to a number.
How Much Extra Should You Order?
This is where most people go wrong — either ordering exactly to the m² (and running short) or adding far too much. Here’s a sensible guide:
Straight lay / brick bond — 10%
Standard cuts at edges. Minimal waste with rectangular rooms.
Herringbone / chevron — 15%
Angled cuts at every edge. Significantly more waste than straight lay.
Diagonal layout — 15%
Similar to herringbone — every edge requires an angled cut.
Rooms with alcoves / niches — 15–20%
More corners = more cuts = more waste. Shower niches, boxed pipes, and alcoves all add cuts.
Large-format tiles in small rooms — 10–15%
Fewer tiles overall, but each offcut represents a larger % of the tile area.
💡 Pro Tip:
Always keep 2–3 spare tiles from the same batch after installation. Tile colours can vary subtly between production batches (even with the same product code), so having spares from your original order means any future repair will match perfectly. We note your batch number on every order.
Quick Reference: Typical Irish Bathroom Sizes
Rather than measuring from scratch, here are pre-calculated tile quantities for the most common bathroom sizes in Irish homes. These assume full floor-to-ceiling tiling (2.4m ceiling height), minus one standard door:
Small en-suite (2–2.5m² floor):
Floor tiles: 2.5m²
Wall tiles: 12–14m²
Total + 10%: 16–18m²
Standard en-suite (3–3.5m² floor):
Floor tiles: 3.5m²
Wall tiles: 14–17m²
Total + 10%: 19–23m²
Family bathroom (4–5m² floor):
Floor tiles: 5m²
Wall tiles: 17–22m²
Total + 10%: 24–30m²
Large bathroom (6–8m² floor):
Floor tiles: 8m²
Wall tiles: 22–28m²
Total + 10%: 33–40m²
Downstairs WC / cloakroom (1.5–2m² floor):
Floor tiles: 2m²
Wall tiles: 8–10m²
Total + 10%: 11–13m²
Not tiling every wall? If you’re tiling only the shower area and a splashback behind the basin (a common budget-conscious approach), reduce the wall tile figure by roughly 40–50%. The floor stays the same.
Quick Reference: Kitchen Floors & Splashbacks
Small kitchen floor (6–8m²): 7–9m² tiles needed
Medium kitchen floor (10–14m²): 11–16m² tiles needed
Large / open-plan floor (18–30m²): 20–33m² tiles needed
Splashback only (1.5–3m²): 2–3.5m² tiles needed
Full-height splashback (3–6m²): 3.5–7m² tiles needed
For kitchen splashback details, materials, and costs, see our dedicated guide: Kitchen Splashback Ideas for Irish Homes.
Measuring Tips That Avoid Mistakes
Floors
Measure the longest length and widest width of the room. For L-shaped or irregular rooms, break the floor into rectangles, measure each one, and add them together. Always measure in metres.
Walls
Measure the width of each wall and multiply by the height you’re tiling to. Add all walls together, then subtract windows (approximately 0.5m² each) and doors (approximately 1.8m² each). If you have a bath panel, measure that separately and add it to your total.
Shower enclosures & niches
Don’t forget the inside walls of a shower enclosure — a standard 900×900mm shower has approximately 4.5m² of wall area inside. Shower niches are small (typically 0.12m²) but if you’re using a different tile inside the niche, calculate it separately.
⚠️ Common Mistake:
Measuring the room perimeter and multiplying by ceiling height gives you the total wall area including the door and window. Always subtract these — a standard door saves you nearly 2m² of tiles.
From Square Metres to Boxes
Tiles are sold by the box, and each box covers a specific number of square metres.
30 × 60cm tiles: 1.08–1.44m² per box
60 × 60cm tiles: 1.08–1.44m² per box
60 × 120cm tiles: 1.44m² per box
20 × 20cm tiles: 1.00m² per box
Mosaic sheets: ~1.00m² per box
Always round up to the next full box. If you need 22.3m² and each box covers 1.44m², you need 16 boxes.
Worked Example: A Typical Wexford Bathroom
Let’s say you have a standard en-suite measuring 2.5m × 1.4m (3.5m² floor area), with a 2.4m ceiling, one door, and no window. You want full floor-to-ceiling tiling in 60×120cm porcelain.
Floor: 2.5 × 1.4 = 3.5m²
Walls:
Two long walls = 12m²
Two short walls = 6.72m²
Minus door = 16.92m²
Total: 20.42m²
Add 10% waste = 22.5m²
At 1.44m² per box, you need 16 boxes. Tile cost: approximately €790–€1,240.
🧮 Don’t want to do the maths?
Send us your room dimensions and we’ll calculate exactly how many tiles and boxes you need — free of charge. Get in touch – or visit us in Gorey.
Ready to Bring These Trends Home?
Browse our 2026 collections online, order free samples to test in your own lighting, or visit our Gorey showroom to see the latest tiles and fixtures in person.
Frequently Asked Questions
How many tiles do I need for a bathroom?
A typical Irish family bathroom (4–5m² floor) with full floor-to-ceiling tiling needs approximately 24–30m² of tiles including 10% waste. A small en-suite (2–2.5m² floor) needs around 16–18m².
How do I calculate tiles per square metre?
Measure all surfaces, subtract doors/windows, then add 10–15% waste depending on layout.
How much extra tile should I order for waste?
10% for standard layouts, 15% for herringbone or diagonal, 15–20% for complex spaces.
How many tiles come in a box?
Typically 1.08–1.44m² per box depending on size. Always round up.
Can I return unused tiles?
Yes — unopened boxes can be returned. This is a key advantage of buying locally.
