Room Painting Calculators

These calculators price a single interior room. You put in the dimensions, the condition of the walls and how many coats you want, and you get the paint quantity, the labour hours and a cost range. Every one of them runs on the same coverage figures and production rates, so a bedroom and a hallway are priced the same way even though they behave differently.

Pick the room you are painting from the list below. If you are pricing a whole property rather than one room, the whole house calculators will be faster, and if you only need the trim, doors or cabinets, use the interior detail calculators instead.

Pick your room

How a room is measured

Every one of these calculators wants the same three numbers to start: length, width and ceiling height. Wall area comes from the perimeter multiplied by the height, so you do not need to measure each wall separately unless the room is an unusual shape.

From there the calculator subtracts nothing for doors and windows by default, which is deliberate. On a normal room the openings are roughly cancelled out by the extra cutting in they create around frames and sills, and painters who deduct openings and then forget to add the cut-in time usually end up short. The full method, including when it is worth deducting, is in how to measure a room for painting.

What changes the number most

Condition, not size. A sound wall that has been painted before takes one pass. A wall that needs filling, sanding and a mist coat can take several times the labour for the same area, and prep is the single most underestimated item in interior work. There is a proper treatment of it in how to account for prep time in a painting estimate.

Coat count is the other lever. A colour change from a mid tone to a bright white, or anything going over a strong red or yellow, will need more coats than a like for like refresh. Decide the colour before you price, because it moves the figure more than most people expect. See how many coats of paint do I need.

Rooms that behave differently from their size

Two rooms of identical floor area can be very different jobs. A hallway has a small wall area but a large number of door casings, so it is cut-in heavy and slower per square foot than the number suggests. A bathroom is small but needs a moisture tolerant product and has awkward access around fittings. A kitchen has less open wall than its footprint implies, because cabinets and appliances occupy it, and the cabinet doors are a separate job entirely with its own cabinet calculator.

Small rooms carry a further trap. The fixed cost of turning up, protecting the floor, opening the paint and cleaning up does not shrink with the room, so the cost per square foot of a closet or a laundry room is always high. For a contractor that is what a minimum job charge exists to cover.

Paint quantity, and why the tin is optimistic

The spread rate printed on a tin is measured on a smooth, sealed, primed surface in ideal conditions. Real walls are none of those things. Texture, porosity and colour change all reduce coverage, sometimes substantially, and bare or repaired plaster will drink the first coat. These calculators use working figures rather than the label figure for that reason. The background is in how much does a gallon of paint cover.

Buy a little more than the calculation says. Running out mid wall means a trip to the supplier and, if the batch differs, a visible join. The material side is covered in how to estimate paint and material costs, and choosing the finish itself in the paint sheen guide.

If you are quoting this for a customer

These calculators give you the cost of doing the work. A price is a different number: it has to carry your overhead and your profit on top of the job cost, and it has to be built on what an hour actually costs you rather than the wage you pay. Start with painting labor burden and painting business overhead, then price the job using how to bid a painting job. The full stack from measurements to a quotable figure is in the contractor pricing calculators.

Every room type, side by side

These are the default dimensions each room calculator starts from, and what those dimensions produce. Use them to find the room closest to yours, then adjust in the calculator itself.

The column worth studying is trim. A hallway is one of the smallest rooms by floor area and carries 70 linear feet of trim, more than a master bedroom at 48, because it is almost entirely door casings. Trim is priced by length rather than area, so it does not follow room size at all.

Why the kitchen has no ceiling figure

Kitchen ceilings are usually left alone when the cabinets are staying, so the kitchen calculator excludes it by default. If you are doing the ceiling as well, add it back in the calculator rather than assuming the default includes it.

The rooms that cost more than their size

Bathrooms and laundry rooms are the smallest rooms here and among the slowest per square foot. Almost every surface in them is an edge: around the vanity, the cistern, the window reveal, the door casing. There is very little open wall to roll, which is exactly what makes a room fast.

The reverse is true of a living room. It is the largest room in the table and one of the most straightforward, because most of its area is uninterrupted wall.

Frequently asked questions

How do I calculate how much paint a room needs?

Multiply the room perimeter by the ceiling height to get wall area, then divide by the coverage rate for your surface and multiply by the number of coats. The calculators above do this for you and use working coverage figures rather than the optimistic number on the tin, which assumes a smooth sealed surface.

Should I subtract doors and windows from the wall area?

Usually not. On a normal room the area saved by openings is roughly offset by the extra cutting in they create around frames, sills and casings. Deducting the openings and then failing to add that cut-in time is a common way to end up short on both paint and hours.

Why is a small room so expensive per square foot?

Because the fixed part of the job does not shrink. Travel, setting up, protecting the floor, opening and cleaning materials and packing down cost roughly the same whether the room is a closet or a lounge. That fixed block is spread over very little area, so the rate per square foot looks high even when the price is fair.

Do these calculators include the ceiling and trim?

You can include or exclude them. Ceilings are priced at their own coverage and production rate because they are slower to roll overhead, and trim is priced by linear foot rather than by area. If you only want the trim, doors or mouldings, the interior detail calculators handle those on their own.

Are these calculators free?

Yes. All of them run in the browser, none of them ask for a signup or an email address, and there is nothing to install. The paid product is a separate quoting tool for contractors who need to send branded estimates to customers.

How accurate is the estimate?

It is as accurate as the inputs. The coverage figures and production rates behind it are realistic working numbers rather than best case ones, but no calculator can see the condition of your walls or how much furniture has to be moved. Treat the output as a well founded starting figure, and adjust for anything unusual about the room in front of you.

Which room calculator should I use for an odd shaped room?

Pick the closest type and adjust the dimensions, or use the custom room option. The calculation works from perimeter and height rather than from a named room, so the label matters less than getting the measurements right.

Why does a hallway need so much trim paint?

Because it is mostly door casings. A hallway carries around 70 linear feet of trim against 48 in a master bedroom, despite being far smaller. Trim is measured by length, so it does not follow floor area.