About the Paint Calculator
A gallon of paint doesn't stretch as far as most people assume, especially once a second coat and typical wall texture are factored in, so a quick calculation up front avoids a mid-project run to the store.
How It Works
The calculator multiplies your total wall area by the number of coats you're applying, then divides by the paint's coverage rating per gallon to estimate total gallons needed, with the same total also converted to liters.
Examples
A standard bedroom
400 sq ft of wall area with 2 coats at 350 sq ft coverage per gallon needs about 2.29 gallons, essentially two full gallons plus a bit extra.
A single accent wall
A smaller 120 sq ft wall at 2 coats needs about 0.69 gallons, well under one gallon, though most stores don't sell partial gallons so you'd still buy a full one or a quart.
Advantages
- Accounts for multiple coats instead of assuming a single pass
- Shows results in both gallons and liters
- Includes a coat comparison chart for 1, 2, and 3 coats
Common Mistakes
- Buying for one coat when the project needs two
- Using the coverage rating for a different sheen or paint line than what's actually being purchased
- Not adjusting coverage downward for textured or unprimed surfaces
Edge Cases to Watch For
- Textured, unprimed drywall, or a much lighter color going over a much darker one, all reduce actual coverage below the can's stated rating.
- Doors, windows, and trim aren't subtracted from wall area here, so for rooms with unusually large openings, subtracting their area first gives a tighter number.
- Primer is a separate product with its own coverage rate, not included in this paint estimate.
Common Use Cases
- Budgeting a room repaint before buying materials
- Comparing paint needs between a single accent wall and a full room
- Estimating primer or stain quantities using the same area figure