Paint, Wallpaper and Tile Calculator
This paint calculator can be used to work out how much paint you need to cover the walls and ceiling of a room as well as calculating how many rolls of wallpaper you will require, how many tiles you will need, how many boards and joists you will require to complete a deck and how much treatment a fence will require. Simply select the job you wish to complete and enter the required measurements in metres. The answer will update as you enter the required information.
How much paint do I need for a room?
Example: a 3.5 m × 3 m bedroom with 2.4 m walls, one door and one 1.2 m window.
Paint for the walls
4.3 litres
- Tins for the walls
- 1 × 5 L
- Wall area to paint
- 28.3 m²after taking off 2.9 m² for doors and windows
- Paint for the ceiling
- 1.6 litres1 × 2.5 L (10.5 m²)
- Worked at
- 2 coats, 13.0 m² per litre
Estimates for general information only, not advice. See Important information below.
How many rolls of wallpaper?
Example: the same bedroom papered all round in plain paper.
Rolls to buy
7 rolls
- Drops (strips) needed
- 25each cut at 2.50 m
- Drops from each roll
- 410.05 m × 0.53 m roll
- Pattern repeat
- none (plain or free match)
Doors and windows are not taken off, so the offcuts cover the awkward bits around them. Buy every roll with the same batch number.
Estimates for general information only, not advice. See Important information below.
How many tiles do I need?
Example: a 2.4 m × 1.2 m bathroom wall in 300 × 600 mm tiles.
Tiles to buy
18 tiles
- Area to tile
- 2.88 m²
- Tiles to cover it exactly
- 16
- Extra for cuts and breakages
- 10%
- Boxes
- 36 tiles per box
Estimates for general information only, not advice. See Important information below.
How many deck boards and joists?
Example: a 3.6 m × 3 m deck in 144 mm boards.
Deck boards
21 boards
- Board layout
- 21 rows × 1 board144 mm × 3.6 m boards, 6 mm gaps
- Joists across the deck
- 10 × 3.00 m400 mm centres, both ends of the frame included
- Frame sides
- 2 × 3.60 m
- Noggins
- 182 rows, no more than 1.2 m apart
- Deck area
- 10.80 m²
Estimates for general information only, not advice. See Important information below.
How much fence paint do I need?
Example: eight 6 ft × 6 ft (1.83 m) panels, one side.
Fence treatment
4.5 litres
- 5 litre tins
- 1
- Area to cover
- 26.8 m²
- Worked at
- 1 coat, 6.0 m² per litre
Estimates for general information only, not advice. See Important information below.
Room makeover planner
Turns the quantities above into a job order for painting walls and ceiling, with the other things you will need to buy. No prices.
Written by Anthropic’s Claude AI from the figures above. What you enter is sent to it to write the plan, so please don’t include personal details.
Quick reference: paint for common rooms
Two coats, 2.4 m walls, one standard door and one 1.2 m × 1.2 m window taken off. Room sizes are examples; measure your own.
| Room | Wall area | Walls at 13 m²/L | Walls at 14 m²/L | Ceiling at 13 m²/L | Plain wallpaper rolls |
|---|---|---|---|---|---|
| Small bedroom3.0 m × 2.5 m | 23.5 m² | 3.6 L | 3.4 L | 1.2 L | 6 |
| Medium bedroom3.5 m × 3.0 m | 28.3 m² | 4.3 L | 4.0 L | 1.6 L | 7 |
| Large bedroom4.5 m × 3.5 m | 35.5 m² | 5.5 L | 5.1 L | 2.4 L | 8 |
| Living room5.0 m × 4.0 m | 40.3 m² | 6.2 L | 5.8 L | 3.1 L | 9 |
Coverage figures as at 16 October 2026: Dulux EasyCare Washable & Tough Matt (up to 13 m² per litre), Crown Walls & Ceilings Matt (14 m² per litre), Ronseal One Coat Fence Life (6 m² per litre), Cuprinol Less Mess Fence Care (up to 24 m² per 5 L, one coat). Tile allowance from Tile Mountain; joist and noggin spacing from Wickes; 10 cm trim per wallpaper drop as used by Jane Clayton. Coverage varies with the product, the colour change and the surface, so always check the tin.
How it works and where the numbers come from
Paint starts from the wall area (the room's perimeter times its height, minus a standard 1981 × 762 mm door and your windows), multiplied by the coats and divided by the coverage. We start with figures the manufacturers publish, checked on 16 October 2026: Dulux says its EasyCare Washable & Tough Matt covers up to 13 m² per litre, Crown gives 14 m² per litre for its Walls & Ceilings Matt, Ronseal rates One Coat Fence Life at 6 m² per litre and Cuprinol says a 5 litre tin of Less Mess Fence Care covers up to 24 m² in one coat. Wallpaper follows the method used by Jane Clayton, adding 10 cm to each drop for trimming. Tiles get the 10% (straight) or 15% (diagonal and herringbone) allowance recommended by Tile Mountain. Decking uses the joists at 400 mm and noggins no more than 1.2 m apart set out in the Wickes guide. Coverage varies with the product, the colour underneath and the surface, so check the tin.
A worked example
A 3.5m x 3m bedroom with 2.4m high walls and one door and one window 1.2m square gives approx 28.3m² of wall. Two coats at 13m² per litre = 4.3 litres, so one 5 litre tin, plus 1.6 litres for ceiling. Papering the same room in plain paper would be 25 drops, or 7 rolls at 4 drops per roll.
Questions people ask
Why does the calculator round up?
Running out halfway down a wall is worse than having some left over. There is one clear example of this and that is for wallpaper. It is best if all of the rolls of wallpaper required for a room are of the same batch number so that the colour matches, as later purchases may not.
Should I take doors and windows off for wallpaper?
They are left in the wallpaper sum, as is the case with Jane Clayton’s calculator, and off-cuts can be used round any framed areas, with the corners wasting more than people expect.
How much extra paint for a dark colour change?
Dulux state that a strong colour change may require additional coats, so set the coats to three and the calculator will calculate the paint required.
Does it work for rough sawn fences?
Yes, but rough sawn and weathered wood soaks up more. Cuprinol aims Less Mess Fence Care at rough sawn timber, so its lower coverage is the safer pick.
Important information
This tool gives general information and estimates only. It is not financial, tax, legal, medical or other professional advice, and it does not take your personal circumstances into account.
Coverage and quantities vary by product, surface, colour and method. Always follow the manufacturer's instructions on the tin or packaging, buy a little extra, and follow safety guidance for tools, ladders and chemicals.
The figures are based on the published sources and dates shown on this page. Prices, rates and rules change, so they may be out of date by the time you read this. Check them with the supplier, provider or official source, or ask a qualified professional, before you make a decision.
The AI-written explanation is produced automatically by Anthropic's Claude from the figures on this page. It can contain mistakes and should not be relied on.
We don't keep what you enter. If you use the AI explanation, what you entered is sent to Anthropic so it can write it.
You use this tool at your own risk. Perky Pad accepts no responsibility for any loss, cost or decision made as a result of using it, as far as the law allows.