Show the formula and working
This floor paint calculator works out how many litres and tins of floor paint you need for a garage, workshop, utility room or any painted concrete or timber floor, for homeowners in the UK and Europe working in metres. Enter the floor size, the coverage on your tin and the number of coats, and it adds an allowance for porous or rough floors so you buy enough for every coat.
Quick answer: Multiply floor length by width to get m², multiply by the number of coats, divide by the coverage on the tin and add about 10%. A 4 m by 3 m floor is 12 m², so two coats at 12 m² per litre need 2.2 litres. The floor paint calculator rounds this up to one 2.5 litre tin.
What Is a Floor Paint Calculator?
A floor paint calculator is a tool that turns the area of a floor into the litres and tins of floor paint needed for the coats you plan to apply. The formula is: litres = floor area in m² x coats / coverage in m² per litre x (1 + waste percentage). Floor area is length x width, plus any steps or extra rooms, minus areas you will not paint such as fitted units.
How Do You Use the Floor Paint Calculator?
- Enter Floor length and Floor width in metres, or switch to feet.
- Add Extra area such as steps or a second room, and enter any Area to leave unpainted.
- Enter the Coverage from the tin in m² per litre. The 12 m² per litre default is only an example.
- Set Coats, usually 2 or 3, and Extra for porous or rough floors.
- Choose the Tin size you plan to buy.
- Read the litres and tins, then open “Show the formula and working” to see each step.
How Much Floor Paint Do I Need for a Garage?
Allow about 1 litre of floor paint for every 6 m² of garage floor when you apply 2 coats of a paint that covers 12 m² per litre, plus 10% for porous concrete. Ronseal states that its Diamond Hard Garage Floor Paint covers up to 12 m² per litre, and that a 2.5 litre tin covers 10 m² with 3 coats.
Bare, dusty or new concrete absorbs more paint than a sealed or previously painted floor, so measure carefully and round up. For timber decking outdoors, a stain is usually the better choice, and the deck stain calculator works out how much you need.
| Floor area | 2 coats at 12 m² per litre, plus 10% | 3 coats at 12 m² per litre, plus 10% |
|---|---|---|
| 10 m² | 1.83 litres | 2.75 litres |
| 12 m² (4 m x 3 m) | 2.2 litres | 3.3 litres |
| 15 m² | 2.75 litres | 4.13 litres |
| 20 m² | 3.67 litres | 5.5 litres |
| 30 m² | 5.5 litres | 8.25 litres |
How Many Coats of Floor Paint Do You Need?
Most floor paints need 2 coats, and 3 coats give the most protection on garage floors that take car traffic. Ronseal recommends 3 coats for maximum protection with a minimum of 2, while Rust-Oleum says one coat of its one part epoxy floor paint is enough, with an optional second coat after 24 hours. Follow the instructions for the paint you buy.
How Far Does a Litre of Floor Paint Go?
A litre of floor paint covers roughly 4 to 12 m² per coat, depending on the product and how porous the floor is. The Rust-Oleum one part epoxy floor paint data sheet gives 300 to 400 ft² per US gallon on smooth concrete, about 7.4 to 9.8 m² per litre, and 180 to 220 ft² per gallon on porous concrete, about 4.4 to 5.4 m² per litre.
How Long Before You Can Drive on a Painted Garage Floor?
Wait at least 72 hours before driving onto a newly painted garage floor, and up to 5 days for some epoxy floor paints. Ronseal says its garage floor paint is hardest after 72 hours, and Rust-Oleum allows 5 days for vehicle traffic on its one part epoxy. Light foot traffic is usually possible much sooner.
Worked Example: A Utility Room Floor
Example: the concrete floor of a 4 m by 3 m utility room is being painted. The tin states 12 m² per litre. Plan 2 coats, add 10% for the porous concrete and buy 2.5 litre tins.
- Floor: 4 m x 3 m = 12 m².
- Paint: 12 m² x 2 coats / 12 m² per litre = 2 litres.
- With 10% extra: 2 x 1.10 = 2.2 litres.
- Tins: 2.2 / 2.5 = 1 tin of 2.5 litres, with about 0.3 litres spare.
With 3 coats, the same floor would need 3.3 litres, or two 2.5 litre tins. For the walls of the same room, the paint calculator works out the emulsion, and the paint and decorating calculators section has the rest of the decorating tools.
Floor Paint Calculator FAQs
How much floor paint do I need for 20 m²?
For 20 m² you need about 3.67 litres for 2 coats or 5.5 litres for 3 coats, at 12 m² per litre with 10% extra. A 5 litre tin covers 2 coats comfortably but not quite 3 coats with the allowance.
Do I need to prime a concrete floor before painting?
It depends on the product. Some floor paints are self priming or ask you to thin the first coat, while others need a separate primer or sealer on bare concrete. Check the tin, and make sure the floor is clean, dry and free of oil first.
How long should I wait between coats of floor paint?
Recoat times range from about 4 hours to 24 hours. Ronseal gives 4 to 6 hours for its water based garage floor paint, while Rust-Oleum asks for 24 hours before a second coat of its one part epoxy.
Can I use floor paint on wooden floorboards?
Many floor paints are suitable for both concrete and wood, but not all. Check the tin lists timber, sand the boards, fill gaps and remove dust first. For a clear finish that shows the grain, use a floor varnish instead.
Why does new concrete need more floor paint?
New and bare concrete is porous and soaks up the first coat, so coverage can drop to around half the tin’s best figure. Rust-Oleum’s data, for example, roughly halves coverage on porous concrete compared with smooth concrete.
How do I calculate floor paint for an L shaped room?
Split the room into two rectangles. Enter the larger rectangle as the floor length and width, then add the smaller one’s area in the extra area box. The calculator adds them before working out litres.
Checked October 2026. Sources: Ronseal: Diamond Hard Garage Floor Paint, Rust-Oleum: Concrete and Garage 1-Part Epoxy Floor Paint data sheet, Wikipedia: Gallon (US gallon 3.785 litres).