How to estimate a painting job

To estimate a painting job, measure the surfaces in square feet, subtract doors and windows, multiply by the number of coats, then divide by the coverage on the manufacturer's data sheet to get the gallons. Then add labour based on your own production rate, surface prep, access, overhead and profit, and finish with GST and QST.

Step 1: measure the surfaces in square feet

Everything starts with the takeoff. A mistake here carries into every line that follows: gallons, hours and price. Measure on site when you can, or work from current drawings.

For the walls of a room, the quickest method is perimeter times height. A 40 ft by 25 ft room has a 130 ft perimeter. With 12 ft walls, that is 1,560 sq ft of wall. Ceilings get their own line (length times width), since they rarely go at the same pace or take the same product.

Keep surfaces that need different work on separate lines too: trim, door frames, columns, steel. One line per surface type makes the quote easier to defend when the client starts asking questions.

Step 2: subtract doors and windows

Work out the area of each opening and take it off the total. A 4 ft by 5 ft window is 20 sq ft. A 3 ft by 7 ft door is 21 sq ft. If you are painting the frames or the doors themselves, price them on their own line.

Some contractors leave small openings in the total to cover the extra cutting-in around them. Either way works. What matters is doing it the same way every time, or your numbers stop being comparable from one job to the next.

Step 3: coats and product coverage

Multiply the net area by the number of coats. Two coats on 1,377 sq ft means 2,754 sq ft to cover.

Take the coverage from the manufacturer's data sheet, not from memory. For example, Benjamin Moore lists its Regal Select flat at 37.2 to 41.8 m², or 400 to 450 sq ft, per 3.79 L can. That is theoretical coverage at the recommended film thickness. On porous drywall, stucco or a big colour change, you will cover less. Use the low end of the range, or lower, based on what you have seen on your own jobs.

Industrial coatings are different: the data sheet gives volume solids and a target dry film thickness. Real coverage then also depends on how you apply it and on losses, which run higher with a spray gun than with a roller.

Step 4: number of containers

Divide the area to cover by the coverage you chose and round up. In our example, 2,754 sq ft divided by 400 sq ft is 6.9 gallons, so 7 cans of 3.79 L. If an 18.9 L pail costs less for the same volume, price both. Add primer if the job needs it, with its own coverage figure.

Count the sundries as well: tape, drop sheets, roller covers, brushes, cleaner. Each one looks small. Forget them on ten quotes a month and it adds up.

Step 5: labour hours

This is where a painting estimate is won or lost. Divide the paintable area by your production rate in square feet per hour. That rate comes from your past jobs, not from a standard. No official body in Quebec publishes painting production rates, and a number from a forum knows nothing about your crew or your sites.

To build your rate, take a few finished projects, write down the square feet painted and the actual hours, and divide. Do it by surface type. Rolling smooth walls, ceilings, brushing trim and spraying steel are four different rates.

Then price surface prep separately: moving and masking, scraping, patching, sanding, washing, final cleanup. On a renovation, prep can take longer than the painting. If you bury it in your production rate, you will never know which one cost you money.

Use a loaded hourly cost: wages, benefits, employer contributions, travel time. On a site covered by the CCQ, that cost also has to follow the sector's conditions.

Step 6: access and equipment

Once you go past what a stepladder can reach, plan for access: rolling scaffold, boom lift, scissor lift. Count the rental, delivery, setup, teardown and the time the crew spends moving it around. A 12 ft ceiling or a stairwell can change the price of a job that looked simple.

Step 7: overhead and profit

Overhead covers what no single job pays for: the office, insurance, vehicles, software, and the time spent on quotes you did not win. Work out your percentage from last year's financial statements, with your accountant if needed.

Profit goes on after that. Watch the difference between markup and margin: adding 10% to your costs does not give you a 10% margin on the selling price. In the example below, 10% on $2,438 is $243.80, about 9.1% of the price before tax.

Step 8: GST and QST

GST is 5% and QST is 9.975%. QST is calculated on the price without GST, for a combined 14.975%. Revenu Québec gives the example of a $13,000 sale: $650 in GST and $1,296.75 in QST. Show both taxes on separate lines with your registration numbers.

Your RBQ licence number has to be on the quote as well. Quebec's Building Act (s. 57.1) requires it on estimates, tenders, contracts and statements of account.

Worked example: a 40 ft by 25 ft commercial space

Here is a fictional quote, from takeoff to total. The product price, hourly cost, production rate and percentages are made up for the example. Swap in your own.

When the job is done, compare the 21 estimated hours with the actual hours. Doing that on every project is what makes your production rate something you can trust.

If you sign at the client's home

When a contract with a consumer is solicited or signed somewhere other than your place of business, Quebec's Consumer Protection Act can treat it as an itinerant merchant contract. The client can then cancel at no cost within 10 days of receiving their copy, and you cannot take a deposit during that period. Check the Office de la protection du consommateur's rules before you settle on how you sign jobs.

How OKTO PSA helps you build the quote

OKTO PSA for construction has an industrial paint calculator built into the quote: coats, solids, containers, drying time and coverage in sq ft per hour. You start from a template, group lines by area or surface type, and the OKTHAV assistant checks the quote before it goes out against your target and minimum margins.

The client signs online in their portal. The accepted version becomes the order, then the project, and each group of lines becomes a phase with its own budget. Hours entered by phase then give you the real production rate for every job. See construction quotes for the details, or try the interactive demo without a long sign-up. To track hours, see construction timesheets and phases and sub-projects. For showing your licence number, read our RBQ licence guide.

This guide is not legal or tax advice. The examples are fictional. For your own situation, talk to a lawyer, your accountant, the RBQ, the Office de la protection du consommateur or Revenu Québec.

Sources: Benjamin Moore, Regal Select flat data, Revenu Québec, calculating taxes, Building Act, s. 57.1, RBQ, displaying your licence, Office de la protection du consommateur, itinerant merchant contracts, checked on October 27, 2026.