Paint Quantity Calculator
Calculate the exact amount of paint needed for your project based on surface area and coats
Room 1
Paint Settings
Pricing (optional)
Results
Step-by-Step Calculation
How to Calculate Paint Quantity
Estimating paint starts with measuring the total paintable area, subtracting openings like doors and windows, then dividing by the paint's spread rate and multiplying by the number of coats.
Step-by-Step Method:
- Measure the perimeter of the room (length of all walls)
- Multiply the perimeter by the wall height to get gross wall area
- Subtract the area of doors (~21 ft² each) and windows (~15 ft² each)
- Add ceiling area if painting the ceiling (length × width)
- Add trim/baseboard linear footage if painting trim
- Divide total area by spread rate (ft² per gallon)
- Multiply by number of coats
- Round up to the nearest purchasable container size
Standard Deduction Sizes
| Opening Type | Typical Size | Area Deducted |
|---|---|---|
| Standard Door | 3' × 7' (80 × 200 cm) | 21 ft² (1.95 m²) |
| Standard Window | 3' × 5' (90 × 150 cm) | 15 ft² (1.39 m²) |
| Large / Picture Window | 6' × 5' (180 × 150 cm) | 30 ft² (2.79 m²) |
| Sliding / Patio Door | 6' × 7' (180 × 210 cm) | 42 ft² (3.90 m²) |
Paint Container Sizes
Sample / Half Pint
8 oz
~25 ft² (1 coat)
Test colors, small touch-ups
Quart
32 oz
~87 ft² (1 coat)
Accent walls, trim, small projects
Gallon
128 oz
~350 ft² (1 coat)
Most common — 1 average room
5-Gallon Bucket
640 oz
~1,750 ft² (1 coat)
Multiple rooms, best per-gallon price
Paint Buying Tips
- Always round up — it's better to have leftover paint for touch-ups than to run short
- Buy all your paint at once from the same batch to ensure color consistency
- 5-gallon buckets cost less per gallon and ensure a single consistent mix
- Keep at least a quart of extra paint for future touch-ups and repairs
- Most stores accept returns on unopened gallons — check the return policy
- Higher-quality paint covers better and lasts longer, often needing fewer coats
- For trim and accent walls in a different color, calculate those areas separately
- Don't forget to account for closet interiors if you plan to paint those too
Related Calculators
Note: This calculator provides estimates based on standard room dimensions and industry-average coverage rates. Actual paint consumption depends on surface condition, paint quality, application method, and color. Always check the manufacturer's stated coverage and buy extra for touch-ups.
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