Interior paint cost calculator

What actually drives an interior painting quote

Painters do not price a room by the room. They price it by the square foot of surface they have to cover, and then adjust for how awkward that surface is to reach. Two rooms with identical floor plans can be quoted hundreds of dollars apart because one has nine-foot ceilings, crown moulding and a stairwell, and the other is a plain box with one door.

That is why this calculator asks for length, width and height rather than “small, medium or large”. The surface area is the number the trade actually works from, and once you have it, the rest of the estimate is arithmetic you can check.

Surface area, not floor area

The walls in a 14 by 12 foot room with nine-foot ceilings come to 468 square feet, which is nearly three times the 168 square feet of floor. Add the ceiling and you are close to 640. This is the single most common reason a homeowner is surprised by a painting quote: they were thinking about the floor.

Doors and windows come back off. A standard interior door is about 21 square feet and a typical window about 15, and painters subtract them because they are not painting them as wall. They are not free, though — cutting in around an opening is slower than rolling flat wall, which is part of why the labour rate per square foot is not the same as the rate for a bare new-build room.

Coats are not optional the way people hope

One coat works when you are going over the same colour in the same sheen with a quality paint. Every other situation needs two: covering a dark colour, going from flat to eggshell, painting over a patched wall, or using a light colour over anything. A single coat that does not cover is not cheaper, because the second coat still has to happen and the setup happens twice.

A gallon covers roughly 350 square feet in one coat on a smooth, primed surface. On new drywall, on heavy texture, or over a colour change, real coverage drops and the calculator rounds up, because you cannot buy four fifths of a gallon.

Doing it yourself versus hiring out

On a single room, labour is usually somewhere between half and three quarters of a professional quote. That is the number you are deciding about. Materials for a typical bedroom run well under two hundred dollars whoever holds the brush.

What you are buying with the labour line is speed, a clean cut line, and the preparation that makes the finish last — filling, sanding, caulking gaps, and proper masking. A professional crew does a bedroom in a day. The same room takes a careful amateur a weekend, and the cut lines around the ceiling are where the difference shows for the next ten years.

Doing it yourself makes most sense in a plain room with low ceilings and a colour that is not a dramatic change. It makes least sense in a stairwell, on a high ceiling, or anywhere you would need to hire staging — that is where amateurs get hurt and where the finish is hardest to keep straight.

What a fair painting quote includes

A complete quote names the paint by manufacturer and product line, not just “premium paint”. It states the number of coats. It says what preparation is included: filling nail holes and small dents, sanding, caulking gaps at trim, and spot-priming bare patches. It says what is being protected and how, and it says who moves the furniture.

It should also be explicit about what is not included. Wallpaper removal, repairs to damaged drywall, lead paint work in a house built before 1978, and painting the inside of closets are all common exclusions that become change orders later.

Trim is a separate line for a reason

Baseboard, door casing and window casing are priced by the linear foot because they are slow, detailed work with a different paint. Trim enamel costs more than wall paint, it needs a better brush, and it needs the wall work to be finished first. Including trim on a typical bedroom adds roughly ninety linear feet, which is why it moves the number as much as it does.

Where this estimate can be wrong

It assumes a room in ordinary condition: sound walls, a standard ceiling height you can reach from a step ladder, and no repairs beyond filler. It does not price wallpaper removal, water damage, mould remediation, skim coating a badly patched wall, or the extra containment required when disturbing paint in a pre-1978 house.

It also assumes one room. Painters quote a whole-house job at a lower rate per square foot than a single room, because the setup, the masking and the travel are spread across more work. If you are painting four bedrooms, expect the per-room figure to come down.

Finally, the state adjustment moves labour only. Paint costs within a few percent of the same amount everywhere in the country, because it ships nationally. A painter’s time does not.

How to use the number you just got

Take the typical figure into the conversation, not the low one. Ask the painter for their square-foot rate and the number of coats, and check the arithmetic against what this page gave you. If a quote is far above the high end, the difference is usually preparation the painter has spotted and you have not — ask what it is. If it is far below the low end, ask what has been left out.