Painting Prep + Spray-Rate Calculator
Paint gallons by spray / roll / brush + surface type + coats, with separate prep-time line by prep severity (light through restoration).
2 is standard. 1 is risky on most colors. 3 for dark over light.
Builder grade: $25. Standard: $45. Premium: $70+.
Often a helper-rate; sometimes same as painter
Result
- Coverage rateFor Roller on Drywall — painted (recoat)
- 400 sf/gal
- Paint gallons
- 6 gal
- Primer gallons
- —
- Paint cost
- $270
- Primer cost
- $0
- Apply labor
- 8.0 hr · $440
- Prep labor
- 2.0 hr · $90
- Total (material + labor)
- $800
- Effective $ / sq ft
- $1
This estimate is based on national average costs and may vary by region, project specifics, and market conditions. Use as a starting point for your bids.
Coverage rates: what really happens in the field
The 350-sq-ft-per-gallon figure on the back of a paint can is best case: smooth surface, roller, one coat, mid-grade paint. Real-world coverage drops with surface texture, application method, and color difference. This calculator uses a coverage matrix that adjusts for both.
Method comparison
| Method | Apply rate | Coverage drag | Setup time |
|---|---|---|---|
| Spray (HVLP / airless) | 1,500 sf/hr | −25% (overspray) | High (masking) |
| Roller | 300 sf/hr | baseline | Low |
| Brush | 80 sf/hr | −10% (lap waste) | Lowest |
The break-even is roughly 500 sq ft of contiguous surface. Below that, masking eats the spray advantage. Above it, spray wins decisively — especially on cabinets, ceilings, and trim.
Prep — the variable that breaks bids
Walking the job and grading prep on a four-level scale is the single biggest accuracy gain you can make on painting bids:
- Light (1,200 sf/hr): dust off + tape + drop cloths. Common for repaints.
- Moderate (600 sf/hr): minor scrape + spot patches + sand. Standard residential.
- Heavy (300 sf/hr): extensive scrape + multiple patches. Aging houses.
- Restoration (150 sf/hr): strip + repair + heavy sand. Historic / disaster.
Pricing benchmarks
- Interior walls, 2 coats: $1.50–3.50 per sq ft installed
- Ceilings: +30% over walls (overhead work, more setup)
- Trim and millwork: +50–100% over walls
- Exterior: +50% over interior (weather risk, ladders, prep)
- Cabinet refinish (spray): $40–80 per door + $20–40 per drawer
Frequently asked questions
How much paint do I need per square foot?
One gallon of paint covers about 350–400 sq ft on smooth painted drywall with a roller (one coat). Spray coverage drops to 250–300 sq ft per gallon because of overspray. Rough surfaces (raw wood, masonry) cut that further — masonry can drop to 120 sq ft per gallon. Always plan for two coats; one-coat coverage is marketing copy, not real-world performance.
Spray vs roll vs brush — what's the production-rate difference?
Spray (HVLP or airless): ~1,500 sq ft per hour of application. Roller: ~300 sq ft per hour. Brush: ~80 sq ft per hour. Spray is 5× faster than roller but burns through more paint per sq ft and demands far more masking. For a single bedroom, roller wins on total time. For a whole-house repaint, spray wins.
Should I always prime before painting?
Required: raw drywall, raw wood, masonry, metal (with rust-converter primer), drastic color changes (dark over light), water-stained surfaces. Skippable: same-color recoat on previously-painted drywall in good condition. Quality primer ($25–35/gal) blocks stains and improves topcoat adhesion — the time cost is worth it on anything non-trivial.
How much should I budget for prep?
Prep is where most painting jobs go over budget. Light prep (dust + tape + mask): 1,200 sq ft per hour. Moderate (scrape + small patches + sand): 600 sq ft per hour. Heavy (extensive scrape + multiple patches): 300 sq ft per hour. Restoration (strip + repair): 150 sq ft per hour. Walking the job before quoting and pricing prep separately is the difference between a profitable bid and a money loser.
How do I price a paint job per square foot?
Walls only, smooth drywall, 2 coats: $1.50–3.50/sq ft installed. Add 30% for ceilings (more setup and overhead work). Add 50% for exterior. Add 100%+ for trim and detail work. The variance comes from prep severity, paint quality, and finish level — a Level 5 finish ($75/gal paint, fine brushwork) prices very differently from a Level 3 quick-flip.
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