--- title: "Paint Calculator UK: Litres of Emulsion by Room in m² | AumnI tools" description: "Work out litres of emulsion, ceiling paint and gloss for each room from lengths in metres, doors and windows, coats and texture, rounded up to 2.5 litre tins." url: https://aumnitools.com/uk/tool/paint-calculator category: "Lifestyle" country: "United Kingdom" updated: 2026-11-08 --- # Paint Calculator Decorating a UK house means measuring in metres, reading coverage in square metres per litre and buying emulsion in tins that rarely match what you need. This version starts in metres and litres, uses 12 m² per litre as its typical figure, and rounds each product up to whole 2.5 litre tins. ## United Kingdom rules and figures - UK homes are measured in metres and square metres, so this version starts in metres, litres and square metres per litre. - Wall emulsion starts at 12 square metres per litre. That is what manufacturers typically quote and is not an official figure, so read the spread rate on your own tin. - The tin size starts at 2.5 litres, and no price is filled in because shop prices vary by brand and finish. - The standard rate of VAT in the UK is 20%, so type the price per tin as you pay it at the till. Sources: [HMRC: United Kingdom tax authority (VAT rates)](https://www.gov.uk/government/organisations/hm-revenue-customs) (checked 2026-11-08) ## How the Paint Calculator works Wall area is the room’s perimeter times its height, minus a standard door and window for each one you count. Trim covers skirting, both faces of each door and the architrave. Each product’s area, coats and spread rate give litres, which round up to tins. Formula: `litres = (m² × coats) ÷ (m² per litre ÷ texture factor ÷ colour factor); tins = litres ÷ tin size, rounded up` - Doors are deducted at 0.81 × 2.03 m and windows at 0.9 × 1.2 m, and you only enter how many of each. Skirting is taken as 0.15 m high and architrave 0.09 m wide. - Wall and ceiling emulsion start at 12 m² per litre. Woodwork and primer start at 300 ÷ 350 of that, which is 10.3 m² per litre, because gloss and undercoat spread less far. - The colour slider starts at 50 and raises wall and woodwork paint by 17.5%, since a bold change needs more hide. Ceilings do not get that uplift. - The tin starts at 2.5 litres and no price is filled in, so enter the cost of one tin to see the total. ## How to use the Paint Calculator 1. **Measure the rooms.** Enter each room’s length, width and ceiling height in metres, with the number of doors and windows. Add room starts another. 2. **Say what is being painted.** Tick walls, ceiling and woodwork separately for each room, since a hall may only need its woodwork redone. 3. **Describe the wall.** On Paint needed choose the surface, such as bare plaster or a textured finish, and set how far the colour is changing. 4. **Add tin size and price.** Check the tin size in litres, type what one tin costs in pounds, and switch on primer for new plaster. 5. **Take the list to the shop.** Copy list gives text for a message, or Export CSV gives a spreadsheet of litres and tins per product. ## Example: A living room and bedroom in metres, 2.5 litre tins The 5.5 × 4.3 × 2.7 m living room (2 doors, 2 windows, walls, ceiling and woodwork) and the 3.7 × 3.4 × 2.7 m bedroom (1 door, 1 window, walls only) have 83.09 m² of net wall, 23.65 m² of ceiling and 12.03 m² of woodwork. Two coats of wall emulsion need 16.27 litres, which is 7 tins. The ceiling takes 3.94 litres (2 tins) and the woodwork 2.74 litres (2 tins). That is 22.96 litres and 11 tins. ## When to use the Paint Calculator - **Repainting a rented flat.** Add the rooms you are allowed to paint and see how many 2.5 litre tins of emulsion the walls and ceiling need. - **Fresh plaster after a rewire.** Choose bare plaster, switch on primer, and read the extra mist-coat litres before ordering. - **Woodwork only.** Tick only the woodwork box in the hall and landing to price a gloss refresh without paying for wall paint. - **Comparing tin sizes.** Change the tin to 5 litres or 1 litre and see how the leftover and the number of tins change. ## What the Paint Calculator does not do - The starting spread rates are typical manufacturer figures, not an official standard, so a tin that states a different rate needs that figure typed into the spread-rate box. Other countries start with litres and no price, which you enter. - Doors and windows use one standard size each, so a patio door or a large picture window is under- or over-deducted. - Rooms are rectangles with flat ceilings and no alcoves, stairs, gables or radiators. - The texture and colour factors are rules of thumb, not a paint maker's data. Check the spread rate printed on your tin. - Nothing is saved: the rooms reset to the two examples when you reload. ## When something else is a better fit - **When you want floor area, perimeter and a boxes-of-material order for flooring**, use the [Room Measurement Calculator](https://aumnitools.com/tool/room-measurement-calculator.md). - **When you need to convert gallons, litres or square measures**, use the [Unit Converter](https://aumnitools.com/tool/unit-converter.md). - **When the surface is exterior brick, a ceiling with beams or a spray job**, use the paint manufacturer's own calculator or a trade quote. ## Questions about the Paint Calculator ### How many litres of emulsion does a 4 by 3 metre bedroom need? About 7 litres for the walls alone, depending on height and openings. The 3.7 × 3.4 × 2.7 m starter bedroom with one door and one window has 35.62 m² of net wall, and two coats need 6.97 litres. ### What coverage does the calculator assume? It assumes 12 m² per litre for wall and ceiling emulsion, then divides it by a texture factor and a colour factor. At the default slider of 50, walls spread at about 10.2 m² per litre. ### Why does it want more paint than the tin label suggests? Tin labels quote a best case on a smooth, sealed wall. The calculator lowers the figure for texture and for a big colour change. Set the slider to 0 and the surface to smooth to see the label number. ### Do I need to measure doors and windows? No, only count them. Each door removes 1.64 m² of wall and each window 1.08 m². For a patio door or a bay, add the nearest number of standard openings instead. ### How do I price the job? Type what one tin costs in the price box and the tool multiplies it by the whole tins for each product. Because tins round up, a small excess of litres can add a whole extra tin. ## Related tools - [Room Measurement Calculator](https://aumnitools.com/tool/room-measurement-calculator.md): Floor, wall and volume totals for several rooms, in feet or metres - [Unit Converter](https://aumnitools.com/tool/unit-converter.md): Converts 102 units in 11 categories, with temperature offsets and 0 to 12 decimals - [Home Maintenance Reminder](https://aumnitools.com/tool/home-maintenance-reminder.md): 45 home jobs with set intervals; log last-done dates to see what is overdue ## About this page Runs in your browser: what you enter is processed on this device and is not uploaded. Last checked against the tool's code on 2026-11-08. Interactive version: https://aumnitools.com/uk/tool/paint-calculator