How to Estimate an Exterior Painting Job

Eyeballing an exterior paint job is the fastest way to give away profit. Come up short on gallons, prep hours, or second story access and the difference comes straight out of your margin. Come in too high and the homeowner signs with someone else. The fix is a repeatable process: measure accurately, figure material from the manufacturer's data, estimate labor from production rates, and set the price with a margin formula.

How to Measure Paintable Area

1. Rectangular walls: wall length times height, from the foundation line to the eave. A 40 ft wall that is 10 ft tall is 400 SF.
2. Gables: the triangle is base times rise, divided by 2. A 30 ft wide gable with an 8 ft rise is 120 SF.
3. Windows and doors: subtract the openings. Measuring each one is the most accurate. Plenty of estimators use a standard deduction per window and door, but measure picture windows, sliders, and garage doors.
4. Trim and fascia: price these in linear feet (LF). Run the fascia along eaves and rakes, then add window and door casing, corner boards, and band boards. Soffit goes in SF.
5. Doors, shutters, and extras: price them each (EA). A front door or a set of shutters takes more time than its square footage suggests.

Account for texture. Stucco, rough sawn siding, and weathered wood soak up more paint than smooth surfaces, which lowers your real coverage per gallon.

Material: Gallons, Coats, and Waste

The core formula:

Gallons = (net SF x number of coats) / coverage per gallon

Do not guess coverage. Pull it from the product label or the manufacturer's technical data sheet. It is usually listed as a range, and on rough or porous surfaces you should use the low end.

On coats:

• One coat can work when you repaint the same color over a sound surface, if the manufacturer allows it.
• Two coats is standard for color changes, weathered surfaces, or when you want the best finish and durability.
• Primer: bare wood, repairs, and patches always get primer before topcoat.

Add a loss factor for what stays in buckets, rollers, and lines, plus overspray if you are spraying. Spraying loses more material than brush and roll, especially on windy days.

Surface Prep: Where Jobs Are Won or Lost

Paint lasts as long as the prep under it. Price prep as its own line so the customer sees what they are paying for.

• Pressure washing: removes dirt, mildew, and loose paint. Let the surface dry before painting, based on weather and substrate.
• Scraping and sanding: remove all failing paint and feather the edges so they do not telegraph through.
• Caulking: seal trim joints, corners, and window perimeters with a paintable caulk.
• Priming bare wood: every spot scraped down to bare wood needs primer.
• Pre-1978 homes: may have lead based paint. The EPA RRP rule requires lead safe work practices and certification for that work. Build it into your cost and schedule.

Protection, Application Method, and Access

Masking and protection: cover windows, doors, light fixtures, walkways, nearby vehicles, and landscaping. Count the plastic, tape, drop cloths, and the hours it takes.

Spray versus brush and roll: spraying moves faster on large walls but takes more masking and more material. Brush and roll is slower but controlled. On rough or porous surfaces, back-rolling right behind the sprayer pushes paint into the texture and improves adhesion. If you plan to back-roll, carry the extra hours.

Access: a single story ranch with a step ladder does not cost the same as a two or three story home. Extension ladders, scaffolding, or a rented lift are real costs, so list them as a line item.

Labor by Production Rate

Figure hours from your own crew's production rates, not a number you found online:

Hours = quantity to paint / production rate per hour

Run it separately for walls (SF per hour), trim (LF per hour), prep, and masking. Multiply the hours by your fully burdened labor rate, including payroll taxes and insurance, not just wages.

Overhead and Profit: The Right Formula

Add up direct costs (material, labor, equipment rental), then add your overhead share (insurance, trucks, office, software, marketing). Then price for margin:

Price = total cost / (1 - desired margin)

That is not the same as adding a markup. If your cost is $1,000 and you add 25%, you charge $1,250 and your real margin is 20%. To earn a 25% margin you need to charge $1,000 / 0.75 = $1,333.

Sample Estimate

These numbers are an example only. Paint, labor, and equipment costs vary by region, brand, and season.

A single story home with two 40 x 10 ft walls (800 SF), two 30 x 10 ft walls (600 SF), and two 120 SF gables (240 SF). Gross area: 1,640 SF. Less 14 windows and 3 doors, measured (270 SF): 1,370 net SF.

• Body paint: 1,370 SF x 2 coats = 2,740 SF. At a sample coverage of 350 SF per gallon that is 7.8 gallons, plus loss, 9 gallons at $55 = $495.
• Trim and fascia: 300 LF, 2 coats, 3 gallons at $60 = $180.
• Primer for bare wood: 1 gallon = $40.
• Caulk, tape, plastic, and sundries: $150.
• Total material: $865.
• Labor: 16 hours prep, 18 hours walls, 15 hours trim, 8 hours masking and cleanup = 57 hours x $35 = $1,995.
• Ladders and equipment: $100.
• Direct cost: $2,960. Allocated overhead: $450. Total cost: $3,410.
• At a 25% margin: $3,410 / 0.75 = $4,547.

Good, Better, Best Options

• Good: standard paint line, one coat when the color stays the same and the surface is sound, basic prep and spot priming.
• Better: premium 100% acrylic line, two coats, full caulking, and primer on all bare wood.
• Best: the manufacturer's top line, two coats, extended prep, doors and shutters included, and whatever warranty the manufacturer offers on that product.

Common Mistakes

• Not deducting windows and doors, or deducting them twice.
• Using the top of the coverage range on a rough surface.
• Calling prep "included" and giving away hours.
• Forgetting scaffolding or a lift on two story homes.
• Adding a markup when you meant to price for margin.

How RoofDesk Helps

In RoofDesk you capture painting measurements on site and drop them into a trade specific proposal template with units by SF, LF, each, or fixed price, plus waste factors. Build good, better, and best options with scope in English or Spanish, and the homeowner accepts and signs from their phone. Log expenses with a photo of the receipt, track cost, overhead, and profit per job, and the suggested price uses the same margin formula from this article. Then send a deposit invoice and get paid by card from the invoice link.

Frequently Asked Questions

Should I deduct every window and door?

Yes, so you are not charging for paint you will not use. Price the casing as trim in linear feet.

How many coats should I estimate?

Two coats is most common for color changes or weathered surfaces. Quote one coat only when you are repainting the same color over a sound surface and the manufacturer allows it. Bare wood always gets primer.

Should I spray or brush and roll?

Spraying is faster on large walls but needs more masking and material. On porous surfaces, spray and back-roll.

Estimate With a Process, Price With Confidence

To see how to build painting proposals with options, digital signatures, and job costing in one place, book a RoofDesk demo.