How Many Spray Cans Do I Need? A Simple Coverage Guide
It's one of the questions we get asked most in the shop: how many cans will I need? Buy too few and you run out halfway through a fill. Buy too many and you've spent money on paint that sits in a cupboard. Here's the rule of thumb we use, with worked examples for a first piece, a shop shutter and a mural wall.
The short answer: plan on one 400ml can covering about 1.5 square metres with one solid coat. Work out your area in square metres, divide by 1.5, multiply by the number of coats, then add 10% for overspray and mistakes.
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How far does a 400ml spray can go?
Manufacturers publish a theoretical figure. Montana Colors, for example, gives MTN 94 a theoretical yield of about 3 square metres per 400ml can. That figure assumes ideal conditions: continuous spraying, a smooth surface, no wind and no overspray.
On a real wall you'll get less. Brick and render soak up paint, wind carries some of it away, and fades and outlines use paint without covering much area. 1.5 to 2 square metres per can is realistic for one solid coat, and planning on 1.5 means you're far less likely to run short.
The formula
Cans needed = area in m² ÷ 1.5 × number of coats, plus 10%, rounded up
To get the area, multiply the width by the height in metres. A wall 4m wide and 2.5m high is 10 m². One coat would be 10 ÷ 1.5 = 6.7 cans, plus 10% is 7.3, so buy 8.
Quick reference table
| Area | One coat | Two coats |
|---|---|---|
| 1 m² | 1 | 2 |
| 3 m² | 3 | 5 |
| 6 m² | 5 | 9 |
| 10 m² | 8 | 15 |
| 20 m² | 15 | 30 |
Based on 400ml cans at 1.5 m² per can, plus 10%. A 600ml can holds one and a half times as much paint, so you'll need about a third fewer of them.
Worked examples
A first piece on a legal wall
Say your piece is about 3m wide and 1.5m high, which is 4.5 m². The fill takes around 3 cans' worth of paint spread across your fill colours. Then you need an outline colour, a background or cloud, and a white for highlights. Most first pieces this size use 5 to 7 cans, which is why a 6-can pack like the Loop Colours Pack works well as a first buy.
A shop shutter
A typical single shop shutter is around 3m wide and 2.5m high, so about 7.5 m². Spraying a solid background in two coats takes 7.5 ÷ 1.5 × 2 = 10 cans, plus 10%, so 11 cans before you've painted any of the design. That's why a lot of artists roller the background and save the spray for the artwork.
With a rollered background, the design on a single shutter typically uses somewhere around 10 to 15 cans, depending on how many colours and how much detail it has. Treat that as a starting estimate: lots of colour changes, fine lettering or rough, rusty metal will push it up.
Thinking of getting your shutter painted instead? Our guide to how much shutter art costs in London breaks down the prices, and you can see recent work on our shutter art page.
A mural wall
A wall 5m wide and 4m high is 20 m². One coat is 15 cans, and two coats is 30. Add outlines, detail and highlights and a mural this size can easily use 30 to 40 cans of spray if you spray everything, or far fewer if the background and big blocks of colour are rollered first.
What changes how many cans you need
- The surface. Smooth, primed boards and metal go furthest. Rough brick and fresh render can take close to double the paint. A primer or rollered base coat saves a lot of spray.
- Light over dark. Yellow or white over a dark wall needs extra coats. Lay down a white or light base first and your colours will cover in fewer passes.
- The colour. Some colours, particularly certain yellows and reds, are more transparent than others and may need an extra coat.
- The pressure. High-pressure cans put out paint faster. That's great for covering big areas quickly, but each can empties sooner.
- The cap. A fat cap covers ground faster but doesn't make the can go further. Choose the cap for the job, not to save paint. Our guide to graffiti caps explains the options.
- Your technique. Steady, overlapping passes at a consistent distance waste less paint than going back over patchy areas.
- The weather. On a windy day, a surprising amount of paint never reaches the wall.
Roller the background, spray the art
For anything bigger than a few square metres, a roller and a tin of exterior paint costs far less than spraying a solid background. Most muralists roller the base colours and keep the spray for the design, the fades and the detail. Use a paint made for the surface: masonry paint for walls, and a metal paint for shutters.
Buy in packs to bring the price down
When you need a lot of cans, pack prices add up quickly:
- MTN Vice 12-pack: £48, which works out at £4 a can
- MTN Vice 6-pack: £27, or £4.50 a can
- Loop Colours Pack: 12 cans for £54 or 24 for £108, both £4.50 a can
- Loop Black 12-pack and Loop White 12-pack: £54 each
Single Loop cans are £4.75, so a 24-can pack saves you £6 compared with buying the same cans one at a time.
Buying for a school, a council project, a production or a big mural? Send us your list through our trade and bulk orders page and we'll quote line by line, with invoices that work with purchase orders.
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Order online for UK delivery, or choose free click and collect from our shop at 389 New Cross Road, London SE14 6LA, usually ready within 24 hours.
Spray paint coverage FAQs
How many square metres does a can of spray paint cover?
Plan on about 1.5 square metres per 400ml can for one solid coat on a real wall. Manufacturers quote more, around 3 square metres for MTN 94, but that's under ideal conditions with no overspray.
How many cans do I need for a graffiti piece?
A small piece of 4 to 5 square metres usually takes 5 to 7 cans once you include fill, outline, background and highlights. Bigger pieces scale up from there using the formula above.
How many spray cans does a shop shutter take?
Roughly 10 to 15 cans for the design on a single shutter if the background is rollered. Spraying a solid two-coat background as well adds about 11 more.
Does a 600ml can go further than a 400ml can?
Yes. A 600ml can holds one and a half times the paint of a 400ml can, so it covers about one and a half times the area.
How many coats of spray paint do I need?
Usually two for solid colours, and more if you're putting a light colour over a dark one. Detail work and fades often need just one.
Is it cheaper to buy spray paint in packs?
Usually. Our Loop and MTN Vice packs bring the price down to between £4 and £4.50 a can, compared with £4.75 for a single Loop can.