Interior Paint Calculator
Calculate interior paint needed by specifying wall area, number of coats, and paint coverage rate for smooth drywall.
Formula & Explanation
This calculator is designed for interior smooth drywall surfaces. It uses a straightforward approach: Formula: Gallons = (Wall area × Number of coats) ÷ Coverage per gallon Example: 280 sqft × 1 coat ÷ 400 sqft/gallon = 0.7 gallons The calculator then rounds up to the next whole gallon can (e.g., 0.7 gallons → purchase 1 can).
Assumptions
- •Interior smooth drywall surface (flat or primed); textured surfaces may need 25-50% more paint
- •Paint coverage: interior latex typically 350-400 sqft/gallon, varies by sheen and quality
- •One coat provides minimal coverage; two coats are standard for uniform color
- •Wall area should be pre-calculated (measured height × width, minus doors/windows if desired)
- •Does not include primer; use primer-calculator for primer estimates
- •Assumes standard interior conditions (dry climate, normal humidity)
- •Baseboard, crown molding, and trim are not included; calculate separately if needed
Example Calculation
280 square feet of interior drywall painted with one coat at 400 sqft/gallon coverage requires 0.7 gallons, round up to 1 gallon can.
Inputs
Results
Interior Paint Coverage by Surface and Sheen
| surface | coverage | sheen | notes |
|---|---|---|---|
| Smooth drywall, flat | 350-400 sqft/gal | Flat | Most popular interior |
| Smooth drywall, eggshell | 350-400 sqft/gal | Eggshell | Slight sheen, washable |
| Smooth drywall, semi-gloss | 350-400 sqft/gal | Semi-gloss | High sheen for kitchens, baths |
| Textured drywall | 300-350 sqft/gal | Varies | Consumes more paint |
| Primer (interior) | 250-350 sqft/gal | N/A | Lower coverage than topcoat |
Frequently Asked Questions
Related Calculators
Paint Calculator
Estimate paint required for a room by perimeter, height, doors, windows, number of coats, and paint coverage rate.
Wall Paint Calculator
Calculate paint needed for a single wall by specifying width, height, coats, and coverage rate.
Primer Calculator
Calculate primer needed for bare drywall, stains, color changes, or new construction using area and coverage rate.
Paint Cost Calculator
Calculate total paint project cost by combining paint material, labor, waste, and tax.
Paint Coverage Calculator
Calculate how far your paint will go by entering gallons available, coverage rate, and number of coats.