Interior painting cost dataset

Floor area to wall area

Take an average room of 150 square feet including hallways — which have a great deal of perimeter for very little area, and therefore raise the ratio. Treat it as square: its side is the square root, its perimeter four times that. Every room is painted on its own faces, so a wall between two rooms is counted once from each side, which is correct because both sides are painted. That gives 4 × ceiling height ÷ √150 square feet of wall per square foot of floor, before openings.

⚠️ The 150 square foot room is a declared estimate and the only assumption in the conversion. It is published rather than buried so that anyone can redo it with the real room sizes of their own house: smaller rooms and more hallway push the ratio up, open-plan space pushes it down. What is not an assumption is that the surface being quoted is never the floor, and that a price per square foot which does not say which surface it means is not comparable to any other.

Surface, coats and gallons

Gallons come from 350 to 400 square feet per gallon per coat, worked at 375. That range is printed on the tin by manufacturers, not estimated here. It is also the only quantity on a painting quote a homeowner can verify after the work: count the empty tins. Note the rate per square foot of floor falling as the house grows — setting up, masking and furniture do not scale, which is why a single room is proportionally the most expensive painting anybody buys.

Scope, condition, colour change and grade

The widest variable is the condition of the walls: $3,530 on identical rooms. The narrowest is the grade of paint: $2,318 between builder grade and premium. That ordering is the practical finding of this dataset, and it is the opposite of how the decision is usually presented in a showroom.

The pre-1978 surcharge, and why it exists

The federal lead programme exempts only minor repair and maintenance, which it defines as work that disrupts Minor repair and maintenance activities are activities … that disrupt 6 square feet or less of painted surface per room for interior activities or 20 square feet or less of painted surface for exterior activities. Six square feet per room is less than one wall of a cupboard, so any real interior repaint is regulated work in a house built before 1978 — and the rule closes the obvious way round it: Jobs, other than emergency renovations, performed in the same room within the same 30 days must be considered the same job for the purpose of determining whether the job is a minor repair and maintenance activity. This dataset carries that as a declared 35% uplift on preparation and painting hours plus a containment line. ⚠️ That percentage is our estimate, not a published figure: no official source states what certification, containment, dust-extracting tools and cleaning verification add to a domestic painting job. What is not estimated is that the work falls inside the programme.

Line items

33% of the reference total comes from estimated rather than official figures. The reference job is 2,000 square feet of floor at 8 foot ceilings — 4,836 square feet of wall and 2,000 of ceiling, 36.5 gallons over 2 coats, and 96.6 trade hours.

The reasoning behind each figure

Paint — builder gradeestimated, ±27%

• Contractor and builder grade wall paint. It covers and it is cheap; it does not survive being washed.
• Coverage is 350 to 400 square feet per gallon per coat on smooth sealed surfaces, which is printed on the tin rather than estimated by us. We work at 375.
• ⚠️ The quantity is the one number in this whole estimate you can verify after the fact: count the empty tins.

Paint — mid rangeestimated, ±24%

• Mid-range washable wall paint, which is what most repaints use and where the value is.
• Better coverage can remove a whole coat from the job, and a coat of labour costs far more than the difference in the tin.
• Coverage is 350 to 400 square feet per gallon per coat on smooth sealed surfaces, which is printed on the tin rather than estimated by us. We work at 375.
• ⚠️ The quantity is the one number in this whole estimate you can verify after the fact: count the empty tins.

Paint — premiumestimated, ±23%

• Premium wall paint: more pigment, better flow, an even finish under raking light.
• ⚠️ On a wall that has had builder-grade preparation nobody will ever see the difference. Buy the preparation first.
• Coverage is 350 to 400 square feet per gallon per coat on smooth sealed surfaces, which is printed on the tin rather than estimated by us. We work at 375.
• ⚠️ The quantity is the one number in this whole estimate you can verify after the fact: count the empty tins.

Primerestimated, ±33%

• One coat over the roller surfaces, when the colour change calls for it or the walls have been patched.
• Cheaper than a third coat of finish paint and better at the job. When somebody says a colour "needs three coats", one of those is usually a primer that has not been named.

Masking, filler, caulk, abrasives and coversestimated, ±52%

• Tape, plastic, drop cloths, filler, caulk, abrasives and the brushes and rollers that get used up. Priced as a lot rather than per item, because that is how it is bought.
• Small money, and a reliable signal: a crew that arrives with enough of it is a crew that intends to mask properly.

Preparation: filling, sanding, caulking and masking

• Between 0.0032 and 0.014 hours per square foot of roller surface depending on the state of the walls — a four-fold range, and the widest single variable on this page.
• ⚠️ On a normal repaint this is as many hours as applying the paint, and on poor walls more than twice as many. It is also the first thing cut from a cheap quote and the only thing that decides whether the wall still looks flat in three years. If two quotes differ a lot, this is almost always where.
• Increased by 35% in a pre-1978 house, where the work falls under the federal lead programme and means containment, tools with dust extraction and cleaning verification.

Cutting in and rolling

• About 0.0033 hours per square foot per coat — roughly 300 square feet an hour. Rolling the middle of a wall is far faster than that; cutting in along ceilings, corners and trim is far slower, and the blend is what a painter actually achieves over a day.
• Which is why walls-only is not much cheaper per square foot than walls-and-ceilings: the cutting-in happens either way.

Trim and door enamelestimated, ±33%

• A harder-wearing enamel rather than wall paint, because trim gets touched, kicked and cleaned. Dearer per gallon, and there is far less of it.
• Quantity from the real trim area: 0.55 square feet per linear foot of skirting and casing, 40 per door counting both faces and the edges, 9 per window surround — all at two coats.

Brushing trim, doors and window casings

• About 0.022 hours per linear foot of trim, 0.85 hours per door and 0.5 per window casing — all brushed, all two coats.
• ⚠️ This is the line that makes small rooms expensive. Trim is priced by the foot and doors by the unit, so a house with panelled doors, deep skirting and a lot of windows costs far more than its floor area suggests. Rooms are not comparable by size alone.

Moving and protecting furniture

• About 0.0018 hours per square foot of floor: furniture to the middle and covered, pictures and curtains down, and all of it back at the end.
• An empty house is meaningfully cheaper to paint, which is worth knowing if the work can happen between tenancies or before moving in.

Lead-safe containment and cleaning verificationestimated, ±55%

• Heavy plastic sheeting, tacky mats, HEPA vacuum consumables and the wipes used for cleaning verification at the end.
• ⚠️ In a pre-1978 house this is not optional above six square feet of disturbed paint per room, and any real painting job passes that on the first wall. The work has to be done by a certified firm, and the certification itself lands in the hourly rate.
• The band is a couple of rooms at the bottom and a whole house at the top.

Not included in this dataset

Repairing damaged plaster or drywall

Filling nail holes and hairline cracks is preparation and is priced here. A hole, a failed joint or a water-stained ceiling is a repair, and it comes before painting rather than as part of it.

Wallpaper removal

Unpredictable by nature: some comes off in sheets and some takes the paper face of the drywall with it. Nobody can price it honestly without testing a corner first.

Lead testing or abatement

The containment and lead-safe practices priced here are what a certified firm does while renovating. Testing for lead, and abatement — permanently removing it — are different services with their own pricing.

Cabinets

Painting kitchen cabinets is a different job with different products, usually sprayed and often taken away to a shop. It is not a trim line item.

Textured or popcorn ceilings

They drink paint, and if they went up before the eighties they can contain asbestos, which means testing rather than scraping. Neither is modelled here.

Furniture that needs two people or a specialist

The furniture line assumes ordinary household contents. A piano, a large aquarium or a wall-mounted television are their own conversation.