Interior Painting Cost Calculator

Estimate what interior painting will cost before you get quotes. Enter the rooms and your choices, and the calculator compares a do-it-yourself budget — paint, primer and supplies — with a professional estimate based on the labour rate you enter.

What drives the cost of interior painting

Interior painting costs come from three places: paint and primer, supplies, and labour. For a do-it-yourself job, labour is your own time, so the budget is mostly materials. For a professional job, labour is the largest part of the price, and painters build in preparation, cleanup, travel, insurance and profit. The calculator estimates both from the same room measurements, so you can see how much hiring out really adds and decide which rooms are worth doing yourself.

How the estimate is calculated

1. Wall area per room = perimeter × wall height, minus about 50 sq ft for a door and two windows.
2. Ceiling area (optional) = length × width per room.
3. Paint = area × coats ÷ 375 sq ft per gallon, rounded to quarter gallons, then priced in whole gallons.
4. Primer (optional) = area ÷ 275 sq ft per gallon, priced at an example $30 per gallon.
5. Trim (optional) = about a quart of trim enamel per room.
6. Professional price = area × your labour rate, plus a per-room allowance for trim, plus the same materials.

The labour rate is deliberately an input rather than a built-in number: it varies a great deal between cities and between a quick repaint and a job with lots of repairs. Enter the rate from a local quote, or use the calculator to compare quotes on a per-square-foot basis.

Worked example

Three bedrooms of about 13 × 11 feet with 8-foot walls have roughly 334 sq ft of paintable wall each, 1,002 sq ft in total. Two coats need about 5.5 gallons, so six gallons at $45 is $270; with $90 of supplies the DIY materials come to about $360, and the job takes an estimated 20 hours of your time. At an example professional rate of $2.50 per square foot, labour is about $2,505, for a total of around $2,865 — roughly $955 per room.

What changes a painting quote

DIY or hire a professional?

DIY makes sense for straightforward rooms with sound walls, standard ceiling heights and a colour change that will cover in two coats — the savings are largely the labour line. Hiring a professional makes sense for high or awkward spaces, extensive repairs, lots of trim and doors, homes with lead paint concerns, or when your time is worth more than the difference. Many people split the job: they paint bedrooms themselves and hire out stairwells, high ceilings and trim.

Getting and comparing quotes

• Ask at least two or three painters to quote the same scope in writing.
• Make sure each quote lists rooms, surfaces (walls, ceilings, trim, doors), number of coats, paint brand and line, and prep work included.
• Divide each quote by the paintable area from this calculator to compare them per square foot.
• Check that the painter is licensed where required and carries liability insurance.
• Clarify who moves furniture, how long the job takes and what the payment schedule is.
• Be cautious of quotes far below the others — they may leave out prep or coats.

Ways to lower the cost

• Do the prep yourself: move furniture, remove outlet covers, fill small holes and sand.
• Keep the same colour family so one or two coats cover.
• Paint walls only and leave good-condition ceilings and trim.
• Buy paint in 5-gallon buckets for large jobs, usually cheaper per gallon.
• Schedule outside peak season if painters in your area offer off-season pricing.

Older homes and lead paint

Homes in the United States built before 1978 may contain lead-based paint. Sanding, scraping or heat-stripping old paint can release lead dust, which is especially harmful to children and pregnant people. If your home is that old, test painted surfaces before disturbing them, and if lead is present use lead-safe work practices or hire a contractor certified under the EPA's Renovation, Repair and Painting (RRP) rule. Simply painting over intact old paint without sanding does not create dust, but preparation that disturbs it needs care.