How much paint for a 30x20 basement?
8 gallons of paint for a 30x20 basement, at the settings most people start with. Below the calculator are the same numbers for the alternatives you are likely to choose, and what each one does to the total.
Reviewed · Method: measured dimensions, industry coverage rates, rounded up to real package sizes · How the numbers are calculated
Values are pre-filled for this page. Change anything and hit Recalculate.
The answer, and what it is made of
30 x 20 ft at a 7.5 ft ceiling gives 1,265 sq ft of paintable wall and ceiling after openings. At 2 coats that is 8 gallons of paint of paint. The primer is a separate line: 4 gal on top of the topcoat budget, not instead of it.
Planning figure for everything on that list: $365 to $853, with $548 as the realistic middle for the products most people actually buy. These are estimates for budgeting, not quotes. Prices move by region and by season, and the middle figure assumes a mid-range product rather than the cheapest thing on the shelf.
Coats multiply rather than add: 8 gallons at 2 coats becomes 11 gallons at 3 coats over bare concrete. The step from one coat to two is the one that actually covers, which is why buying for a single coat almost never finishes the room.
What changes if you change one thing
| Change the number of coats | You buy |
|---|---|
| 2 coats, walls only | 4 gallons |
| 2 coats, walls and ceiling | 8 gallons |
| 3 coats over bare concrete | 11 gallons |
Every row is a live calculation, not an estimate. The shaded row is what this page defaults to.
What goes in the cart
| Item | Quantity |
|---|---|
| Interior paint | 8 gal |
| Primer | 4 gal |
| Roller covers (3/8 in nap) | 4 pcs |
| Angled sash brush 2 in | 2 pcs |
| Painter's tape | 2 rolls |
| Drop cloth | 2 pcs |
| Roller tray + liners | 1 set |
Buy a 5-gallon pail when the total is 4 gallons or more. It is cheaper per gallon and guarantees a single dye lot across connected rooms.
What this size actually changes
Six hundred square feet of floor, 750 of wall and 600 of ceiling at 7.5 ft: eight gallons for two coats over everything. Basements are the one room where the ceiling is unavoidable, because it is the surface that shows damp and discolouration first, and where the paint has to tolerate cooler, damper conditions than anything above grade.
Figure. 30x20 basement: 30 x 20 ft. Measure the finished surface, not the room walls — the area between skirting or cabinet faces is the area you pay for.
How the quantity is worked out
Paint coverage is quoted at 350 to 400 sq ft per gallon per coat on a smooth, previously painted surface. Everything else reduces that number: bare drywall absorbs, a roller with a deep nap wastes, and a strong colour change takes three coats where two were planned. Two coats of the same colour over an existing similar colour is the one case where the label number holds.
Ceilings are the line item people forget. They are the same footprint as the floor, they take a full coat, and they are the slowest surface to paint because of the overhead work. If you are painting a room properly, the ceiling is usually one to two extra gallons on its own.
How to measure this job
Basements need the ceiling height measured in more than one place, because ducts, beams and soffits drop it unevenly. A room that is 8 ft at the centre can be 7 ft 2 in under a beam, and that number decides whether you can use a suspended ceiling or need a direct-mount one.
Measure the perimeter carefully and note every structural pier, because a concrete column is wall you cannot paint and a corner you have to cut around. Below-grade walls are also colder, which changes both paint choice and flooring underlayment.
Mistakes that cost real money
Buying for one coat
One coat only works over the same colour in the same finish. Changing from a dark colour, going from bare drywall, or moving between sheens all need two coats minimum, and a strong colour change needs three. Buying for one coat means a second trip mid-job, in a different batch.
Treating a basement like an above-grade room
Below-grade walls stay cooler and hold more moisture, so standard latex over a damp wall blisters. Use a masonry-appropriate primer and a paint rated for the substrate, and fix any water problem before painting, not after.
Using standard emulsion on a damp basement wall
Latex over a wall with rising damp blisters and peels within a season. Fix the moisture first, then use a masonry-appropriate primer. Painting a damp wall does not solve damp; it hides it until the paint fails, which is more work to repair.
Painting the ceiling last, over everything
Basement ceilings are low and full of pipes and ducts. Rolling a ceiling at 7.5 ft after the walls are finished means drips on fresh paint. Do the ceiling first, cover the floor, then work down.
Frequently asked questions
How much does a gallon of paint cover?
About 350 to 400 sq ft per coat on a smooth, sealed surface. Expect the low end on bare or porous drywall, on a deep-nap roller, and on heavily textured walls. Rough surfaces can drop coverage to 250 sq ft per gallon, which turns a three gallon job into four.
How much paint for a 30x20 basement?
About 8 gallons for two coats on the walls at a 7.5 ft ceiling, plus 3 for the ceiling. Subtract for the stair opening and add for any bulkheads. Bare concrete needs a primer coat first, which adds roughly a third.
How much paint for a 30x20 basement?
About eight gallons for two coats on the walls and three for the ceiling, at a 7.5 ft height. Bare concrete absorbs far more and needs a primer, which typically adds a third again to the total.
What paint is best for a basement?
A washable matte or eggshell with mildew resistance for the walls, and a flat ceiling paint that hides the unevenness. Avoid anything with a strong sheen on a basement ceiling: it highlights every seam and pipe chase.
What will the materials for this cost?
A planning range of $365 to $853 for everything in the shopping list, with $548 as the realistic middle. That is materials only: it excludes labour, delivery, tool hire and disposal of the old surface. Treat it as a budgeting figure, not a quote.