How to estimate a paint job

1. Measure the work, not the house

You are not pricing a 2,400 square foot house. You are pricing some number of square feet of wall, some linear feet of trim, some count of doors, and possibly ceilings — each of which takes a different amount of time per unit.

For interior walls, the usable number is perimeter times ceiling height, less openings. A 16 by 12 room with 9 foot ceilings is a 56 foot perimeter, so 504 square feet gross; take off a door at 21 and two windows at about 15 each and you have 453 paintable square feet. The wall area calculator does this for a whole house if you would rather not.

Keep trim and doors separate. Trim is priced by linear foot and doors per unit because they take time out of all proportion to their surface area — a door might be 21 square feet and take an hour.

2. Convert to hours with your own production rate

A production rate is how many square feet one painter covers in one hour, for one specific kind of work. It is the single most important number in your business and most companies have never measured it.

The rates differ enormously by task. Rolling open wall is fast. Cutting in is slow. Trim, cabinets and detail work are slower again, and heavy prep can take longer than the painting. This is why one blended rate across a whole job produces estimates that are wrong in both directions — too high on the simple jobs you then lose, and too low on the detailed ones you then win.

If you have never measured yours: for the next five jobs, record hours by task, not by job. Within a month you will have rates that beat any published figure, because they describe your crew and your prep standard.

3. Cost the hours properly

The wage is not the cost. Payroll taxes, insurance and workers' compensation sit on top, commonly adding 15 to 30 percent. A painter at $25 an hour with 22 percent burden costs $30.50.

Leaving burden out is the most common single reason a job that looked profitable was not — and because it is a percentage, it scales with the job, so the bigger the job the bigger the hole.

The labor cost calculator takes area, rate, wage and burden and gives you the loaded number.

4. Add materials, and add them honestly

Paint at roughly 350 square feet per gallon per coat on smooth primed surface, dropping toward 250 on rough, porous or bare material. Primer is a separate coat with its own coverage — folding it into the coat count understates both.

Then add the things that never make it onto estimates: tape, plastic, caulk, sandpaper, filler, drop cloths, liners, blades, and the gallon you will have left over. On a residential repaint this line is reliably larger than painters expect.

The paint calculator handles gallons and bucket counts.

5. Cover your overhead

Overhead is everything that happens whether or not you work: vehicles, insurance, phone, software, advertising, rent, your bookkeeper. It has to be recovered from jobs, because there is nowhere else for it to come from.

The straightforward method is to carry it as a percentage of price. Divide last year's overhead by last year's revenue and you have the share every job needs to carry. If that number is 18 percent, then 18 cents of every dollar you quote is already spent before you buy a brush.

The hourly rate calculator approaches the same problem from the other direction and tells you the rate your billable hours have to produce.

6. Decide margin last — and know which number you are setting

Margin is what you keep out of the price. Markup is what you add to cost. They are not the same, and confusing them is a mistake that compounds across every job you quote.

A 50 percent markup produces a 33 percent margin. If you wanted 50 percent and applied a 50 percent markup, you are a third short, on everything, all year. To hit a target margin, divide cost by one minus the margin: a 40 percent margin on $1,000 of cost means a $1,667 price, which is a 67 percent markup.

Worth checking against the markup vs margin calculator before you price another job.

A worked example, end to end

Interior repaint. 1,800 square feet of paintable wall, two coats, smooth primed surface. 240 linear feet of trim and 9 doors. Painters at $25 with 22 percent burden. Overhead at 18 percent of price. Target margin 35 percent.

Walls. At a measured 180 square feet per hour, 1,800 square feet of two-coat work is 20 hours. Loaded at $30.50, that is $610.

Trim and doors. Say 40 hours across trim and doors at the same loaded rate — $1,220. Note how this half of the job is twice the labor of the walls despite being a fraction of the area. That is the thing a blended square-foot rate hides.

Materials. 1,800 square feet at two coats is 10.3 gallons, so 11 to buy; plus trim and door product, plus sundries. Call it $520.

Direct cost is $610 + $1,220 + $520 = $2,350.

Price. Overhead and margin together take 53 percent of the price (18 + 35), so the price is cost divided by 0.47: $5,000. That carries $900 of overhead and leaves $1,750 of profit on 60 hours of work.

Change one input and watch it move. If the trim takes 50 hours instead of 40 — one bad guess on the slowest part of the job — direct cost rises to $2,655 and the same price now yields $1,445, not $1,750. A 25 percent error on one rate cost you 17 percent of the profit.

The part that matters more than the estimate

Record what the job actually took and compare it to what you quoted. Not once — every job. The production rates in your head are hypotheses, and the only thing that turns them into knowledge is measuring the same job twice: once when you price it and once when you finish it.

Companies that do this find, typically, that one or two line items in their pricing are consistently wrong. Fixing those is worth more than any other change available to you, because the error is currently being applied to every quote you send.