How to Estimate a Painting Job: Interior & Exterior Guide

Painting has the tightest margin for error in estimating. Materials are cheap — a gallon of premium paint runs $45-70 — so labor is 75-85% of every job. Miss your production rate by even 20% and a profitable job turns into a break-even favor. The contractors who stay in business aren't better painters. They're better estimators.

This guide is written for painting contractors, not homeowners. We cover the exact measurement formulas, production rates by surface type, material takeoff calculations, and two fully worked examples (interior + exterior) with real 2025-2026 pricing. If you're new to construction estimating in general, start with our complete guide to estimating construction jobs first, then come back here for the painting-specific numbers.

The Two Things Every Painting Estimate Needs

Every accurate painting estimate comes down to two numbers: square footage of paintable surface and realistic production rates. Get both right and your estimate will be within 5-10% of actual cost every time. Get either wrong and you're guessing — and guessing always costs you money.

Square footage tells you how much material to buy and how many labor hours the job requires. Production rates convert those square feet into hours. Everything else — materials cost, labor cost, overhead, profit — is just multiplication once you have those two inputs locked down.

The rest of this guide walks through each step in order: measure, price materials, estimate labor, add prep, apply markup. We finish with two complete examples you can use as templates for your own bids.

Step 1 — Measure the Job

Never eyeball a painting job. A laser distance measurer ($30-80) pays for itself on your first job by eliminating guesswork. Here's how to measure interior and exterior surfaces.

Interior Walls

The formula is simple:

Paintable wall area = (Room perimeter x Ceiling height) - Window area - Door area

• Room perimeter: Measure each wall length and add them. A 12x14 room = 52 linear feet of perimeter.
• Standard ceiling height: 8 ft is standard. 9 ft and 10 ft ceilings are common in newer construction — always verify.
• Window deduction: Standard window = 15 sq ft. Large picture window = 25-30 sq ft.
• Door deduction: Standard interior door = 21 sq ft (3 ft x 7 ft). Sliding glass door = 40 sq ft.

Example: A 12 x 14 bedroom with 8 ft ceilings, 2 standard windows, and 1 door: (52 x 8) - (2 x 15) - 21 = 416 - 30 - 21 = 365 sq ft of paintable wall area.

Ceilings

Ceiling area = room length x room width. A 12 x 14 room = 168 sq ft of ceiling. Ceilings are slower to paint (drip factor, neck strain, cutting in edges) — use a separate production rate.

Trim, Doors, and Baseboards

Measure trim in linear feet, then convert to square feet for material calculations. Standard baseboard is 4-6 inches tall, so 100 linear feet = roughly 40-50 sq ft of paintable surface. Count doors separately — each standard 6-panel door (both sides, jambs, and casing) is about 40-50 sq ft of brush/roller work.

Exterior Surfaces

For exterior, measure each wall face separately. Don't forget gable ends (triangle area = base x height / 2). For a rectangular house:

Exterior wall area = Perimeter x Wall height + Gable area - Window/Door area

A 2-story house with 40 x 25 ft footprint: perimeter = 130 linear feet x 18 ft (two stories) = 2,340 sq ft. Subtract windows and doors (typically 15-20% of wall area), add gable ends. Measure soffits, fascia, and trim separately — these are brush/detail work at a much lower production rate.

Step 2 — Calculate Materials

Paint manufacturers list coverage at 350-400 sq ft per gallon on smooth, primed surfaces. Real-world coverage is lower — textured walls, porous surfaces, and dark-to-light color changes can drop it to 250-300 sq ft per gallon. Use 350 sq ft/gallon as your baseline for estimating.

Always price two coats. One coat rarely provides full coverage and hide. Quoting one coat to win the bid means you either do a bad job or eat the cost of the second coat. Two coats is the professional standard.

Gallons Formula

Gallons needed = (Total sq ft x Number of coats) / Coverage per gallon

Example: 4,000 sq ft of wall area, two coats, 350 sq ft/gallon = 8,000 / 350 = 22.9 gallons. Round up to 24 gallons (buy in 5-gallon buckets when possible — roughly 10% cheaper per gallon than singles).

Material Cost Table

Pro tip:Build a standard consumables kit cost into every estimate. Tape, caulk, sanding supplies, roller covers, and plastic sheeting typically run $150-250 per interior job and $200-350 per exterior job. Don't nickel-and-dime each item — just add a “painting supplies” line item.

Step 3 — Estimate Labor

Labor is where painting estimates are won or lost. Materials are predictable — a gallon of paint costs what it costs. But if you estimate 200 sq ft/hour and your crew produces 140 sq ft/hour, you just gave away 30% of your labor profit. Track your own crew's production rates over 10+ jobs and use those numbers, not industry averages.

Until you have your own data, here are reliable baseline rates:

Calculating Labor Hours

The formula:

Labor hours = Total sq ft of surface / Production rate (sq ft/hour)

Example: 4,000 sq ft of interior walls at 175 sq ft/hour = 22.9 hours. Add 300 linear feet of baseboard at 65 sq ft/hour (roughly 150 sq ft of surface) = 2.3 hours. Add 12 doors at 2.5 doors/hour = 4.8 hours. Total painting labor = 30 hours.

Multiply by your burdened labor rate. If you pay painters $25/hour and your burden (payroll taxes, workers' comp, benefits) is 30%, your burdened rate is $32.50/hour. So 30 hours x $32.50 = $975 in labor cost.

Step 4 — Add Prep Work

Prep is the biggest variable on any paint job and the #1 reason estimates go sideways. A clean repaint over existing paint in good condition needs minimal prep. A house with peeling lead paint, rotted trim, and three layers of wallpaper is a different animal entirely. Always walk the job and inspect surfaces before quoting.

Price prep as separate line items so the client sees what they're paying for — and so you don't forget anything.

Rule of thumb:On a typical interior repaint in decent condition, prep runs 30-40% of your total labor hours. On a neglected exterior with peeling paint, prep can be 50-60% of the job. If your estimate shows prep at less than 25% of labor, you're probably underestimating.

Step 5 — Apply Your Markup

Once you have your total direct costs (materials + labor + prep), you need to add markup for overhead and profit. Most painting contractors use a 35-50% markup on top of direct costs.

Markup vs. Margin — Know the Difference

These are not the same number and confusing them will cost you money:

• Markup is the percentage you add on top of costs. $1,000 cost + 43% markup = $1,430 price.
• Margin is the percentage of the selling price that is profit. $1,430 price - $1,000 cost = $430 profit. $430 / $1,430 = 30% margin.
• A 43% markup = 30% margin. A 50% markup = 33% margin. A 100% markup = 50% margin.

For a deeper dive on pricing strategy, overhead allocation, and how to set your markup based on your real overhead numbers, read our complete contractor pricing guide.

What Markup Should a Painter Use?

It depends on your overhead. If you run a lean operation (just you and one helper, minimal office costs), 35% markup may cover overhead and leave profit. If you have a shop, multiple crews, vehicles, insurance, and an office, you need 45-50%+ markup.

Sanity check:After markup, your interior price should land at $1.50-$3.50 per square foot of wall area in most US markets (2025-2026). If you're significantly above or below that range, re-check your numbers.

Worked Example: 1,500 sq ft Interior Repaint

Let's walk through a complete estimate for a typical interior repaint: 3-bedroom, 2-bath ranch house with a living room, kitchen, and hallway. Existing paint in fair condition, standard 8 ft ceilings, no wallpaper removal. Walls and trim, ceilings stay white (touch-up only).

Measurements

• Master bedroom (14 x 13): Perimeter 54 ft x 8 ft = 432 sq ft. Minus 2 windows (30 sq ft) and 1 door (21 sq ft) = 381 sq ft
• Bedroom 2 (12 x 11): Perimeter 46 ft x 8 ft = 368. Minus 1 window (15 sq ft) and 1 door (21 sq ft) = 332 sq ft
• Bedroom 3 (11 x 10): Perimeter 42 ft x 8 ft = 336. Minus 1 window (15 sq ft) and 1 door (21 sq ft) = 300 sq ft
• Living room (18 x 15): Perimeter 66 ft x 8 ft = 528. Minus 3 windows (45 sq ft) and 1 door (21 sq ft) = 462 sq ft
• Kitchen (14 x 12): Perimeter 52 ft x 8 ft = 416. Minus 2 windows (30 sq ft), 1 door (21 sq ft), cabinets reduce paintable area by ~100 sq ft = 265 sq ft
• Bathroom 1 (8 x 6): Perimeter 28 ft x 8 ft = 224. Minus 1 window (15 sq ft), 1 door (21 sq ft) = 188 sq ft
• Bathroom 2 (7 x 5): Perimeter 24 ft x 8 ft = 192. Minus 1 window (15 sq ft), 1 door (21 sq ft) = 156 sq ft
• Hallway (20 lin ft, 3.5 ft wide): Two walls at 20 ft + two ends at 3.5 ft = 47 ft x 8 ft = 376. Minus 4 door openings (84 sq ft) = 292 sq ft

Total paintable wall area: 2,376 sq ft

Additional surfaces: 280 linear feet of baseboard (~140 sq ft paintable), 12 interior doors (both sides + jambs), 14 window casings.

Full Line-Item Estimate

Price per square foot of wall area: $4,233 / 2,376 sq ft = $1.78/sq ft — right in the sweet spot for a mid-market interior repaint with trim.

Price per square foot of floor area: $4,233 / 1,500 sq ft = $2.82/sq ft — useful for quick sanity checks, though wall area is the more accurate basis.

This example assumes a two-person crew completing the job in approximately 3.5 working days (53.5 labor hours / 2 painters / 8 hours).

Worked Example: Exterior Repaint (2-Story, 2,000 sq ft)

Now let's estimate an exterior repaint: 2-story colonial, 2,000 sq ft floor plan (40 x 25 ft footprint), lap siding in fair condition with some peeling on the south side, 18 windows, 2 exterior doors, attached 2-car garage. Spray + back-roll body, brush all trim.

Measurements

• Wall area: Perimeter (130 ft) x height (18 ft) = 2,340 sq ft
• Gable ends (2): 2 x (25 ft x 6 ft / 2) = 150 sq ft
• Gross area: 2,340 + 150 = 2,490 sq ft
• Minus windows (18 x 15): -270 sq ft
• Minus doors (2 x 21): -42 sq ft
• Minus garage door (16 x 7): -112 sq ft
• Net paintable siding: 2,066 sq ft
• Trim / fascia / soffits: Approximately 350 linear feet of fascia/soffit + 18 window frames + 2 door frames = ~400 sq ft of brush work

Full Line-Item Estimate

Price per square foot of paintable siding: $6,389 / 2,066 sq ft = $3.09/sq ft — competitive for a 2-story exterior with moderate prep.

This job takes a two-person crew approximately 4-5 working days: 1 day power wash (then dry overnight), 1 day scrape/sand/prime/caulk, 1.5 days mask + spray + back-roll body, 0.5-1 day brush trim and doors, 0.5 day cleanup and touch-up.

Note the higher markup (45% vs. 43% for interior). Exterior work carries more risk — weather delays, ladder/scaffold safety, and callbacks are more common. Price accordingly. For more on setting your markup, see our contractor pricing guide.

Common Mistakes That Kill Your Profit

1. Underestimating Prep

This is the #1 profit killer. You walk the job, see walls in “okay” condition, and budget 10% of labor for prep. Then you show up and find 50 nail pops, cracked caulk on every window, and baseboard gaps throughout. Suddenly prep is 40% of the job and you didn't price it. Always walk every room with a notepad and count patches, caulk runs, and problem areas.

2. Quoting Per Room Instead of Per Square Foot

“$350 per room” sounds simple, but a 10 x 10 bedroom (304 sq ft of wall) and an 18 x 15 living room (462 sq ft of wall) are completely different jobs. The living room has 52% more wall area. If you charge the same price, you're losing money on every large room. Measure every room. Quote per square foot internally, even if you present the price differently to the client.

3. Forgetting Trim

Trim, baseboards, window casings, and door frames are slow brush work at 50-80 sq ft/hour — roughly 3x slower than rolling walls. A house with 300 linear feet of baseboard, 14 door frames, and 16 window casings can add 15-20 labor hours. That's $500-650 in labor cost. If you only estimated walls, you just donated your entire profit margin.

4. Not Accounting for High Ceilings and Peaks

A room with 10 ft ceilings has 25% more wall area than the same room with 8 ft ceilings. A two-story foyer or stairwell requires scaffolding or extension ladders, which drops your production rate by 30-40%. Vaulted ceilings, cathedral ceilings, and two-story great rooms should be estimated at half normal production rates — and you may need to price scaffold rental separately.

5. Not Pricing Mobilization

Loading the truck, driving to the job, unloading, setting up, covering floors, taping off — and then doing it all in reverse at the end of each day. On a 3-day interior job, setup and teardown easily account for 4-6 hours of labor. On exterior jobs with ladders, scaffolding, and a sprayer, it's even more. Add a “mobilization / setup” line item to every estimate. Your crew is on the clock from the moment they load the truck.

If you want to see how other trades handle estimating challenges, check out our roofing estimate guide — different trade, same principles.

Frequently Asked Questions