Paint Calculator
Wall area (perimeter × height) minus doors and windows, times coats, divided by the coverage on the can: a 12 × 14 ft room with 8 ft walls needs about 2.12 gallons for two coats, so buy 2 gallons and 1 quart.
Paint estimator
How to calculate how much paint you need
wall area = 2 × (length + width) × height paintable area = wall area − (doors × 21) − (windows × 12) gallons = paintable area × coats ÷ coverage per gallon
Worked example: a 12 × 14 ft room with 8 ft walls has 2 × (12 + 14) × 8 = 416 sq ft of wall. Take off one door and two windows (45 sq ft) to get 371 sq ft. Two coats at 350 sq ft per gallon: 371 × 2 ÷ 350 = 2.12 gallons. That is 1.06 gallons per coat.
The 350 sq ft per gallon default is the figure Benjamin Moore's calculator uses. Your can may say more or less: rough or porous surfaces, dark colors over light ones and spraying all use more paint. BEHR's data sheets note their 250 to 400 sq ft range does not include the loss from spraying.
Paint coverage by brand
Coverage per gallon for one coat, as printed on each product's data sheet or product page:
| Product | Type | Sq ft per gallon | Dry time |
|---|---|---|---|
| Sherwin-Williams Emerald Interior Latex (Matte) | Interior | 350–400 | touch 1 h, recoat 4 h (77°F, 50% RH) |
| Sherwin-Williams SuperPaint Interior Latex (Flat) | Interior | 350–400 | touch 1 h, recoat 4 h (77°F, 50% RH) |
| Sherwin-Williams ProMar 200 Zero VOC Interior (Flat) | Interior | 350–400 | touch 1 h, recoat 4 h (77°F, 50% RH) |
| Benjamin Moore Regal Select Interior (Matte) | Interior | 400–450 | dry 1 h, recoat 1-2 h |
| Benjamin Moore Aura Interior (Matte) | Interior | 350–400 | dry 1 h, recoat 1 h |
| Benjamin Moore ben Interior (Eggshell) | Interior | 400–450 | dry 1 h, recoat 2 h |
| BEHR PREMIUM PLUS Interior (Eggshell) | Interior | 250–400 | touch 1 h, recoat 2 h (77°F, 50% RH) |
| BEHR ULTRA SCUFF DEFENSE Interior (Eggshell) | Interior | 250–400 | touch 1 h, recoat 2 h (77°F, 50% RH) |
| Valspar Signature Interior Paint + Primer | Interior | 200–400 | touch 30-60 min, recoat 2 h (77°F, 50% RH) |
| Sherwin-Williams Duration Exterior Acrylic (Flat) | Exterior | 250–300 | touch 1 h, recoat 4 h (45°F+, 50% RH) |
| Sherwin-Williams Emerald Exterior Acrylic (Flat) | Exterior | 250–300 | touch 1 h, recoat 4 h (45°F+, 50% RH) |
| BEHR MARQUEE Exterior (Satin) | Exterior | 250–400 | touch 1 h, recoat 2 h (77°F, 50% RH) |
| Sherwin-Williams Premium Wall & Wood Interior Primer | Primer | 400 | touch 30 min, recoat 2 h (77°F, 50% RH) |
| Benjamin Moore Fresh Start High-Hiding All Purpose Primer (046) | Primer | 400–450 | touch 1 h, recoat 2 h (77°F, 50% RH) |
| KILZ KILZ 2 ALL-PURPOSE Primer | Primer | 300–400 | touch 30 min, recoat 1 h (77°F, 50% RH) |
How many coats of paint?
- Benjamin Moore's calculator assumes 2 coats and leaves the ceiling out.
- Sherwin-Williams, exterior: "For best results, apply two coats of paint."
- Changing color a lot: Sherwin-Williams says a coat of primer improves the hiding of the new color. New drywall: several data sheets (Sherwin-Williams Emerald, BEHR Premium Plus) call for 2 coats of the paint itself, or 1 coat of primer plus 2 coats.
- Repainting a similar color: Sherwin-Williams Duration and Emerald Exterior allow 1 coat for repaints.
Primer has its own coverage: 400 sq ft per gallon for Sherwin-Williams Premium Wall & Wood, 400 to 450 for Benjamin Moore Fresh Start, 300 to 400 for KILZ 2. Run the calculator a second time with 1 coat and your primer's coverage.
Which sheen where?
| Sheen | Sherwin-Williams suggests | Benjamin Moore suggests (interior) |
|---|---|---|
| Flat | Adult bedrooms, formal living rooms, ceilings, uneven or textured walls | Ceilings, walls in low-traffic spaces |
| Matte | Living rooms, dining rooms, exterior siding | Walls, living rooms, dining rooms, bedrooms |
| Eggshell / satin | Hallways, woodwork, children's bedrooms, family rooms, exterior surfaces | High-traffic walls, living rooms, dining rooms, bedrooms |
| Semi-gloss | Kitchens, bathrooms, utility areas, closet doors, trim | Trim, doors, cabinets, wainscoting |
| Gloss | Wood trim, cabinets, doors, furniture | Trim, doors, cabinets, architectural details |
For bathrooms, Sherwin-Williams says satin or semi-gloss is ideal because it can withstand moisture.
Frequently asked questions
How much paint do I need for a 12x12 room?
With 8 ft walls, a 12 × 12 ft room has 384 sq ft of wall. Minus one door (21 sq ft) and one window (12 sq ft) that is 351 sq ft. Two coats at 350 sq ft per gallon is about 2.01 gallons, so buy 2 gallons. Add the ceiling (144 sq ft) separately if you are painting it.
How many square feet does a gallon of paint cover?
It depends on the product, so read the can. Sherwin-Williams says a gallon generally covers 250 to 400 sq ft. Interior data sheets we checked list 350 to 400 sq ft (Sherwin-Williams Emerald, SuperPaint), 400 to 450 sq ft (Benjamin Moore Regal Select) and 250 to 400 sq ft (BEHR Premium Plus). Exterior flats such as Sherwin-Williams Duration list 250 to 300 sq ft.
Do I need one or two coats of paint?
Plan on two. Benjamin Moore's paint calculator assumes 2 coats, Sherwin-Williams recommends two coats on exteriors for best results, and Sherwin-Williams' interior data sheets say priming plus two coats helps when hiding an old color or painting new drywall. Some data sheets allow one coat when repainting a similar color.
How much paint for a ceiling?
Ceiling area is length × width. A 12 × 14 ft ceiling is 168 sq ft; two coats at 350 sq ft per gallon is 0.96 gallons, so 1 gallon.
How much do I subtract for doors and windows?
Benjamin Moore's calculator subtracts 21 sq ft for each door and 12 sq ft for each window. Sherwin-Williams says to subtract large windows and doors. Measure anything bigger than a standard door or window, such as a patio door.
Should I buy quarts or a gallon?
Four quarts make a gallon. When the leftover after whole gallons needs 3 or more quarts, the calculator rounds up to one more gallon; otherwise it lists the quarts. Keep any leftover for touch-ups.
Sources
- Paint Calculator, Benjamin Moore. Used for: door (21 sq ft) and window (12 sq ft) deductions, 350 sq ft per gallon default, 2-coat assumption.
- Let Us Show You How Much Paint To Buy, Sherwin-Williams. Used for: subtract large windows and doors; read the coverage on the label.
- How to Paint a House Exterior, Sherwin-Williams. Used for: a gallon generally covers 250 to 400 sq ft; two coats on exteriors.
- Product Data Sheet 101.02A: SuperPaint Interior Latex Flat, Sherwin-Williams. Used for: primer for drastic color changes; priming plus two coats for hiding; coverage 350 to 400 sq ft/gal and dry times.
- Product Data Sheet 101.08MAB: Emerald Interior Latex Matte, Sherwin-Williams. Used for: coverage 350 to 400 sq ft/gal and dry times.
- Product Data Sheet 101.81A: ProMar 200 Zero V.O.C. Interior Latex Flat, Sherwin-Williams. Used for: coverage 350 to 400 sq ft/gal and dry times.
- Regal Select Interior Paint, Matte (N548), Benjamin Moore. Used for: coverage 400 to 450 sq ft/gal and dry times.
- Aura Interior Paint, Matte (N522), Benjamin Moore. Used for: coverage 350 to 400 sq ft/gal and dry times.
- ben Interior Paint, Eggshell (N626), Benjamin Moore. Used for: coverage 400 to 450 sq ft/gal and dry times.
- Technical Data Sheet: PREMIUM PLUS Interior Eggshell Enamel, BEHR (manufacturer TDS, hosted by Home Depot). Used for: coverage 250 to 400 sq ft/gal and dry times.
- Technical Data Sheet: ULTRA SCUFF DEFENSE Interior Eggshell, BEHR (manufacturer TDS, hosted by Home Depot). Used for: coverage 250 to 400 sq ft/gal and dry times.
- Signature Interior Paint + Primer, Valspar. Used for: coverage 200 to 400 sq ft/gal and dry times.
- Product Data Sheet 102.06B: Duration Exterior Acrylic Flat, Sherwin-Williams. Used for: coverage 250 to 300 sq ft/gal and dry times.
- Product Data Sheet 102.26FLA: Emerald Exterior Acrylic Flat, Sherwin-Williams. Used for: coverage 250 to 300 sq ft/gal and dry times.
- Technical Data Sheet: MARQUEE Exterior Satin Enamel, BEHR (manufacturer TDS, hosted by Home Depot). Used for: coverage 250 to 400 sq ft/gal and dry times.
- Product Data Sheet 108.38: Premium Wall & Wood Interior Latex Primer, Sherwin-Williams. Used for: coverage 400 sq ft/gal and dry times.
- Technical Data Sheet: Fresh Start High-Hiding All Purpose Primer 046, Benjamin Moore. Used for: coverage 400 to 450 sq ft/gal and dry times.
- KILZ 2 ALL-PURPOSE Primer product data, KILZ (manufacturer label, hosted by Home Depot). Used for: coverage 300 to 400 sq ft/gal and dry times.
- How to Choose a Paint Finish (paint sheen guide), Sherwin-Williams. Used for: which sheen goes where.
- How to Choose a Paint Finish, Benjamin Moore. Used for: which sheen goes where.
Estimates only. Check local codes and your product's label. Found a number that does not match its source? Send a correction.