400 sq ft · 2 coats · 350 sq ft/gal
Input
400 sq ft · 2 coats · 10% wasteOutput
≈ 2.51 gal(400×2)/350×1.10 = 2.51 gallons.
Paint quantity is **net surface area × coats ÷ coverage rate**, with coverage read from the paint can label.
**Formula (imperial):**
Gallons = (Net sq ft × Coats) ÷ Coverage (sq ft per gallon per coat) × (1 + waste%)
**Example — 400 sq ft walls, 2 coats, 350 sq ft/gal, 10% waste:**
(400 × 2) ÷ 350 × 1.10 = **2.51 gallons**
**Example — 12×12 ft wall area (144 sq ft), 2 coats, 350 sq ft/gal:**
(144 × 2) ÷ 350 = **0.82 gallons** (under one gallon)
Subtract **doors** (~21 sq ft each) and **windows** (~15 sq ft each) from gross wall area before calculating. Textured, porous, or unprimed surfaces need a lower coverage number (250–300 sq ft/gal).
The calculator multiplies net paintable area by coats, divides by label coverage rate, and applies an optional waste buffer.
Formula
gal = (net_sq_ft × coats ÷ sq_ft_per_gal) × (1 + waste% / 100)Tap 12×12 bedroom, 400 sq ft walls, or accent wall — or enter your own dimensions on the main form.
Tap Walls · 2 coats, Ceiling · 1 coat, Primer, or Porous surface — each sets coverage and coats.
Imperial: sq ft per gallon per coat. Metric: m² per liter per coat — read from the label.
Enable deductions on the main form — default counts subtract standard opening sizes.
Results show paint to order, base gallons, best retail can fit, and 1 / 2 / 5 gal round-up table.
After walls, estimate LVP or laminate cartons with Flooring Calculator for the same room.
Input
400 sq ft · 2 coats · 10% wasteOutput
≈ 2.51 gal(400×2)/350×1.10 = 2.51 gallons.
Input
12×12 ft · 2 coatsOutput
≈ 0.82 galGolden test vector — under one gallon.
Input
300 sq ft · 400 sq ft/galOutput
0.75 galFlat ceiling — single coat.
Common real-world scenarios where this tool saves time.
400 sq ft walls, 2 coats at 350 sq ft/gal ≈ 2.3 gal — two 1-gal cans plus a quart.
80 sq ft feature wall, 2 coats ≈ 0.46 gal — one quart may suffice.
300 sq ft/gal, 1 coat — porous board absorbs more than finish paint.
35 m² at 8.5 m²/L per coat, 2 coats — matches EU paint can labels.
Step-by-step chains that connect related tools for common tasks.
From wall area to gallons.
| Surface | Coverage range |
|---|---|
| Smooth primed drywall | 350–400 |
| Textured drywall | 250–300 |
| Porous brick / stucco | 200–250 |
| Flat ceiling | 400 |
| Factor | Paint | Wallpaper |
|---|---|---|
| Typical waste | 10% cut-in buffer | 10–15% pattern match |
| Skill level | Moderate DIY | Higher — pattern alignment |
| Remodel speed | 2 coats + dry time | Strip prep + hang time |
Paintable **wall** area is usually much larger than floor area — measure walls or use total sq ft mode.
Most interior jobs need **two finish coats** — double the single-coat gallon count.
Brick, stucco, and unprimed drywall need **250–300 sq ft/gal** — not 400.
Tinted paint varies by batch — buy enough from **one mix** for the whole room.
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Multiply paintable square footage by number of coats, divide by coverage sq ft per gallon from your can, then add 10% waste. Example: 400 sq ft × 2 coats ÷ 350 = 2.29 gal.
If walls total about 400 sq ft paintable area at 2 coats and 350 sq ft/gal: roughly 2.3 gallons. Floor size alone (144 sq ft) is not wall area — measure walls or enter total sq ft.
At 350 sq ft per gallon per coat, one coat covers 350 sq ft — about 0.0029 gallons per sq ft per coat.
Yes for whole-room estimates — each standard door is ~21 sq ft and window ~15 sq ft. Accent walls with no openings can skip deductions.
Most interior walls need two finish coats. New drywall often needs primer plus two finish coats — run primer as a separate calculation with primer coverage (~300 sq ft/gal).
10% covers cut-ins, roller overlap, and touch-ups. Porous surfaces or strong color changes may need 15%.
Multiply gallons by 3.785. The calculator shows both when metric mode is selected.
Flat ceiling paint often covers ~400 sq ft/gal in one coat. Use the Ceiling · 1 coat preset or adjust coverage on the can label.
Use the Primer · 1 coat preset (~300 sq ft/gal) on the same wall area before calculating finish coats separately.
Yes — enter exterior wall sq ft and the coverage rate from your exterior can. Textured siding needs lower coverage numbers.
Room dimensions and paint inputs stay on your device — EverydayTools does not transmit paint calculator data to remote servers.
Estimates only — not professional painting advice. Verify coverage on your paint can for surface type and application method.
Part of Calculator Tools
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Reviewed on 2026-06-27.
350 sq ft/gal — smooth primed drywall
Standard door ≈ 21 sq ft (3×7 ft)
Standard window ≈ 15 sq ft (3×5 ft)
Read from the paint can — smooth drywall is often 350–400 sq ft per gallon per coat.
Coverage reference (verify your can label)
| Surface | Typical coverage |
|---|---|
| Smooth primed drywall | 350–400 sq ft / gal / coat |
| Textured drywall | 250–300 sq ft / gal / coat |
| Porous brick or stucco | 200–250 sq ft / gal / coat |
| Flat ceiling | 400 sq ft / gal / coat |
| Previously painted (repaint) | 350 sq ft / gal / coat |