🎨 Paint Calculator
Calculate gallons of paint, primer, and supplies for any painting project.
Quick Formula
Gallons Needed = Total Paintable Area ÷ Coverage Rate × Number of Coats
Coverage Rates
Standard Paint Coverage
| Paint Type | Coverage (per gallon) | Notes |
|---|---|---|
| Flat/Matte | 350-400 sq ft | Best coverage |
| Eggshell | 350-400 sq ft | Most popular |
| Satin | 300-350 sq ft | Slightly less coverage |
| Semi-gloss | 300-350 sq ft | Kitchens, baths, trim |
| High-gloss | 250-300 sq ft | Trim, doors |
| Primer | 250-400 sq ft | Depends on type |
Coverage Reality
Manufacturer ratings assume ideal conditions. Real-world coverage is usually 10-15% less due to texture, porosity, and application method.
Calculating Wall Area
Basic Room
Wall Area = Perimeter × Height
Example: 12' × 14' room with 8' ceilings
- Perimeter = (12 + 14) × 2 = 52 LF
- Wall Area = 52 × 8 = 416 sq ft
With Openings Deducted
| Opening | Deduction |
|---|---|
| Standard door | 20 sq ft |
| Double door | 40 sq ft |
| Average window | 15 sq ft |
| Large window | 25 sq ft |
Example continued:
- 416 sq ft - (2 windows × 15) - (1 door × 20) = 366 sq ft
Ceiling Area
Ceiling Area = Length × Width
Example: 12' × 14' room = 168 sq ft
Paint Quantity Calculator
Walls Only (Standard Room)
| Room Size | Wall Area (8' ceiling) | Gallons (2 coats) |
|---|---|---|
| 10' × 10' | 320 sq ft | 2 gallons |
| 10' × 12' | 352 sq ft | 2 gallons |
| 12' × 12' | 384 sq ft | 2-3 gallons |
| 12' × 14' | 416 sq ft | 3 gallons |
| 14' × 16' | 480 sq ft | 3 gallons |
| 15' × 20' | 560 sq ft | 3-4 gallons |
Assumes 350 sq ft/gallon coverage, 2 coats, standard deductions
Ceiling Paint
| Room Size | Ceiling Area | Gallons (2 coats) |
|---|---|---|
| 10' × 10' | 100 sq ft | 1 gallon |
| 10' × 12' | 120 sq ft | 1 gallon |
| 12' × 12' | 144 sq ft | 1 gallon |
| 12' × 14' | 168 sq ft | 1 gallon |
| 14' × 16' | 224 sq ft | 1-2 gallons |
Number of Coats Needed
| Surface Condition | Coats Needed |
|---|---|
| Same color touch-up | 1-2 |
| Similar colors | 2 |
| Light to dark | 2-3 |
| Dark to light | 2-3 (with primer) |
| New drywall | 1 primer + 2 paint |
| Patched areas | Spot prime + 2 paint |
| Textured surfaces | Add 15-20% |
| Stain blocking | 1 primer + 2 paint |
Primer Requirements
When to Prime
| Situation | Primer Needed |
|---|---|
| New drywall | Yes — seals paper |
| Patched areas | Yes — spot prime |
| Stains (water, smoke) | Yes — stain blocker |
| Dark to light color | Yes — helps coverage |
| Glossy surface | Yes — or degloss |
| Bare wood | Yes — seals grain |
| Previously painted (good condition) | Usually no |
Primer Coverage
| Primer Type | Coverage |
|---|---|
| Standard latex | 300-400 sq ft/gal |
| Stain-blocking | 200-300 sq ft/gal |
| Shellac-based | 200-250 sq ft/gal |
| Bonding primer | 250-350 sq ft/gal |
Trim & Doors
Trim Paint
| Trim Type | Coverage per Gallon |
|---|---|
| Baseboards | 400-500 LF |
| Door casings | 30-40 openings |
| Window casings | 20-25 windows |
| Crown molding | 250-400 LF |
Doors
| Door Type | Paint Needed (2 coats) |
|---|---|
| Interior door (one side) | ~1/4 gallon |
| Interior door (both sides) | ~1/2 gallon |
| Entry door (one side) | ~1/3 gallon |
| French doors | ~1/2 gallon per side |
Rule of thumb: 1 gallon covers 3-4 interior doors (both sides, 2 coats)
Exterior Painting
Coverage Differences
| Surface | Coverage |
|---|---|
| Smooth wood siding | 350-400 sq ft/gal |
| Rough/textured wood | 200-300 sq ft/gal |
| Smooth stucco | 150-200 sq ft/gal |
| Rough stucco | 100-150 sq ft/gal |
| Brick | 100-150 sq ft/gal |
| Concrete block | 100-150 sq ft/gal |
Exterior Surfaces
Wall Area = (2 × Length × Height) + (2 × Width × Height)
Gable Area = (Base × Peak Height) ÷ 2
Total = Wall Area + Gable Area - Openings
Supplies Needed
Per Room (Average)
| Supply | Quantity |
|---|---|
| Painter's tape | 1-2 rolls (60 yd) |
| Drop cloths | 1-2 (9' × 12') |
| Roller covers | 2-3 per room |
| Brushes | 2" angled for cutting |
| Roller frame | 1 (9" for walls) |
| Extension pole | 1 (for ceilings) |
| Tray liner | 1-2 per room |
| Sandpaper | 220 grit for prep |
Paint Thinner/Cleanup
- Latex paint: Soap and water
- Oil-based: Mineral spirits (1 quart per project)
Production Rates
| Task | Rate (per painter) |
|---|---|
| Prep work | 300-500 sq ft/hour |
| Cutting in | 100-150 LF/hour |
| Rolling walls | 150-200 sq ft/hour |
| Rolling ceilings | 100-150 sq ft/hour |
| Trim (brush) | 100-150 LF/hour |
| Doors | 30-45 min each |
Cost Estimating
| Item | Cost Range |
|---|---|
| Builder-grade paint | $20-30/gallon |
| Mid-grade paint | $35-50/gallon |
| Premium paint | $50-80/gallon |
| Primer | $20-40/gallon |
| Stain-blocking primer | $30-50/gallon |
Paint Quality
Better paint = better coverage + longer life. Premium paints often cover in fewer coats, potentially saving on labor and total paint needed.
Sample Project Estimate
12' × 14' bedroom with 8' ceilings, 2 windows, 1 door:
| Item | Quantity | Notes |
|---|---|---|
| Wall paint | 3 gallons | 2 coats, mid-grade |
| Ceiling paint | 1 gallon | Flat white, 2 coats |
| Trim paint | 1 quart | Semi-gloss |
| Primer | 1 gallon | New drywall |
| Roller covers | 3 | Walls + ceiling |
| Brushes | 2 | 2" angled |
| Tape | 2 rolls | Cut-in edges |
| Drop cloths | 2 | Floor protection |
Common Mistakes to Avoid
- Underestimating paint — Always round up
- Skipping primer — Leads to poor coverage, more coats
- Wrong sheen for the job — Flat in high-traffic areas peels
- Not accounting for texture — Textured walls need 20%+ more
- Buying exact amount — No room for touch-ups later
Keep Extra Paint
Always keep at least 1 quart of each color for touch-ups. Store in a cool, dry place and label with room and date.