Subtract doors (~21 sq ft each) and windows (~15 sq ft each)
2 coats is standard. 1 coat may work with Emerald on light-over-light.
10% for smooth walls, 15% for textured or first-timers
Needed for bare drywall, drastic color changes, stain blocking, or going from dark to light. Emerald and Duration are self-priming on most previously painted surfaces.
Gallons of Paint Needed
3 gallons
SuperPaint Interior — 2 coats over 400 sq ft
Paint Quantity
Buying Options
5-gallon buckets save roughly 10-15% per gallon versus singles. Check your local SW store or sherwin-williams.com for current pricing and promotions.
Cost Estimate
Prices are 2026 retail at Sherwin-Williams stores. SW runs 30-40% off sales multiple times per year. Ask about contractor pricing if you buy regularly.
12,800+ estimates calculated this month
Last updated: 2026-03-16
Sherwin-Williams Paint Coverage by Product
Every SW product has a rated coverage of 350-400 sq ft per gallon, but real-world results depend on the surface you're painting. Smooth drywall gets close to the rated number. Textured walls eat more paint. Stucco and brick can cut your effective coverage nearly in half.
I've painted hundreds of rooms with Sherwin-Williams products over the years, and the coverage numbers on the can are optimistic for anything that isn't smooth drywall. Budget for more than the label says, especially on your first coat. Better to have a quarter gallon left over than to run out with one wall to go.
SW Interior Products at a Glance
| Product | Price/Gal | Coverage | Self-Priming | Best For |
|---|---|---|---|---|
| SuperPaint | $45-$60 | 400 sq ft | No | General rooms, bedrooms, living areas |
| Duration Home | $60-$78 | 400 sq ft | Yes | Kitchens, baths, kids rooms |
| Emerald | $75-$95 | 400 sq ft | Yes | High-traffic, premium finish |
| ProClassic | $55-$72 | 400 sq ft | No | Trim, doors, cabinets |
SW Exterior Products at a Glance
| Product | Price/Gal | Coverage | Self-Priming | Best For |
|---|---|---|---|---|
| A-100 | $38-$52 | 400 sq ft | No | Fences, sheds, rentals |
| SuperPaint | $48-$65 | 400 sq ft | No | Protected siding, low-exposure walls |
| Duration | $65-$82 | 350 sq ft | Yes | Full-house exterior, all climates |
| Emerald | $78-$98 | 350 sq ft | Yes | Sun-exposed walls, coastal, premium |
Prices reflect 2026 SW retail. Contractor accounts and periodic 30-40% off sales bring these numbers down significantly.
Worked Examples
Example A: Master bedroom, 14x16 with 9-ft ceilings, smooth drywall, SuperPaint
- Wall area: (14 + 16) × 2 × 9 = 540 sq ft
- Minus 1 door (21) + 2 windows (30) = 489 paintable sq ft
- SuperPaint at 400 sq ft/gal, 2 coats: 489 × 2 / 400 = 2.45 gal
- With 10% waste: 2.69 gal → 3 gallons needed
- Cost: $135-$180 for paint
Example B: Whole-house exterior, 2,200 sq ft siding, Duration Exterior
- Siding surface factor: 0.80 → adjusted coverage: 350 × 0.80 = 280 sq ft/gal
- 2,200 sq ft × 2 coats / 280 = 15.7 gal
- With 10% waste: 17.3 gal → 18 gallons
- Buying: 3 × 5-gal buckets + 3 singles
- Cost: $1,170-$1,476 for paint
Example C: Kitchen cabinets, ~120 sq ft total surface, ProClassic
- Wood surface factor: 0.90 → adjusted coverage: 400 × 0.90 = 360 sq ft/gal
- 120 sq ft × 2 coats / 360 = 0.67 gal
- With 10% waste: 0.73 gal → 1 gallon
- Plus 1 gallon primer for bare wood: $28
- Total cost: $83-$100 for materials
Surface Coverage Adjustments
| Surface | Coverage Factor | Effective Coverage (400 base) | Why |
|---|---|---|---|
| Smooth drywall | 100% | 400 sq ft/gal | Ideal surface |
| Textured drywall | 85% | ~340 sq ft/gal | Peaks and valleys hold more paint |
| Wood trim/cabinets | 90% | ~360 sq ft/gal | Grain absorption on first coat |
| Lap siding | 80% | ~320 sq ft/gal | Overlap edges, end grain, weathering |
| Stucco | 70% | ~280 sq ft/gal | Rough texture, deep pores |
| Brick | 55% | ~220 sq ft/gal | Highly porous, mortar joints |
Mistakes I see on paint day
- Skipping the math entirely. A lot of painters just grab "a few gallons" and hope for the best. Then they're running back to the store mid-job, losing an hour, and hoping the tint matches. Run the numbers once and you avoid the problem.
- Ignoring surface texture. I've watched guys budget 2 gallons for a 400 sq ft stucco wall and run dry halfway through. Stucco eats paint. So does brick. So does anything with texture. The flat coverage number on the can only applies to smooth surfaces.
- Buying the cheapest line for a high-use room. Your living room can handle A-100 or SuperPaint. Your kitchen cannot. Grease, steam, and constant scrubbing destroy economy paint in under two years. Spend the extra $15/gal now or repaint in 18 months.
- Not boxing the paint. Even within the same color code, there can be slight tint variation between cans. Pour all your gallons into a 5-gallon bucket, stir thoroughly, then pour back into cans. Takes 5 minutes and prevents lap marks between walls.
- Paying retail when sales are every 6-8 weeks. SW has predictable sale cycles. If your timeline allows, wait for the next 30-40% off event. On a 10-gallon job with Emerald, that saves $225-$380.
When to use primer (and when you can skip it)
- Always prime bare drywall. New drywall absorbs paint unevenly. One coat of PVA primer seals the surface and gives you a consistent base for your topcoat.
- Always prime for drastic color changes. Going from dark red to white? Even Emerald will struggle without a tinted primer underneath. Have the store tint your primer close to your final color for better hide.
- Skip primer on clean, previously painted walls in good condition if using Duration or Emerald. Both are self-priming and adhere well to intact existing paint.
- Always prime stain-prone surfaces. Water stains, smoke damage, tannin bleed from knots in wood. These bleed through regular paint. Use a shellac-based primer like BIN or SW's own stain-blocking primer.
Building a full painting estimate? Our painting estimate calculator includes labor and full project costs. If you're pricing exterior work, the square footage calculator helps measure exterior wall area. And EstimationPro puts the whole job together into a professional estimate with line items, labor, and materials. EstimationPro doesn't just build the estimate - it sends the proposal and follows up with the homeowner automatically so you win more of the bids you already send. Try EstimationPro free.
How to Use This Calculator
Pick your Sherwin-Williams product
Choose from 8 popular SW lines: SuperPaint, Duration, Emerald, ProClassic for interior, or SuperPaint, Duration, Emerald, A-100 for exterior. Each has different coverage and pricing.
Select your surface type
Surface texture affects coverage. Smooth drywall gets full rated coverage. Textured walls, stucco, and brick absorb more paint and reduce coverage by 15-45%.
Enter your paintable square footage
Measure wall area and subtract doors (~21 sq ft each) and windows (~15 sq ft each). For rooms, multiply perimeter by ceiling height.
Set coats and review results
Two coats is standard for most jobs. The calculator shows gallons needed, buying options (singles vs. 5-gallon buckets), and cost range at current SW retail pricing.
Paint Quantity Formula
Adjusted Coverage = Base Coverage (sq ft/gal) × Surface Factor
Gallons = (Paintable Area × Coats) ÷ Adjusted Coverage × (1 + Waste%)
Total Cost = Gallons × Price per Gallon + Primer Cost (if applicable)Where:
- Base Coverage
- = 350-400 sq ft/gal depending on SW product
- Surface Factor
- = 1.0 for smooth drywall, down to 0.55 for brick
- Coats
- = Number of coats (typically 2)
- Waste %
- = 10% standard, 15% for textured or less experienced painters
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Frequently Asked Questions
How much does Sherwin-Williams paint cost per gallon in 2026?
Sherwin-Williams pricing varies by product line. A-100 Exterior runs $38-$52/gal, SuperPaint is $45-$65/gal, Duration is $60-$82/gal, and Emerald is $75-$98/gal. These are retail prices. SW runs 30-40% off sales several times per year, and contractors with accounts typically get 25-35% off retail.
How many square feet does a gallon of Sherwin-Williams paint cover?
Most SW paints cover 350-400 sq ft per gallon on smooth surfaces with a single coat. The actual coverage depends on surface texture: smooth drywall gets the full 400 sq ft, textured walls drop to about 340 sq ft, stucco to about 280 sq ft, and brick to roughly 220 sq ft. These are per-coat numbers. Two coats doubles your paint usage.
Is Sherwin-Williams Emerald worth the extra cost?
For most rooms, SuperPaint or Duration is plenty. Emerald makes sense in specific situations: when you need true one-coat coverage (light over light colors), high-traffic areas that get scrubbed regularly, or when the labor cost dwarfs the material cost (paying a crew $2,000+ in labor makes the $30/gal upgrade between SuperPaint and Emerald insignificant). On a 400 sq ft room, the price difference is roughly $60-$80 more for Emerald versus SuperPaint.
Do I need primer with Sherwin-Williams paint?
Emerald and Duration are self-priming on most previously painted surfaces in good condition. You still need a separate primer for: bare drywall or new wood, stain blocking (water stains, smoke damage, tannin bleed), drastic color changes (dark to light), and glossy surfaces that need adhesion help. A good primer like SW PrimeRx or PrepRite runs about $25-$35/gal and covers 350 sq ft.
What is the best Sherwin-Williams paint for interior walls?
SuperPaint Interior is the go-to for most residential repaints. It covers well, cleans up easily, and holds up to normal wear. Step up to Duration for kitchens, bathrooms, and kids rooms because of its antimicrobial additive and better scrub resistance. Emerald is the premium choice when budget allows, with the best washability and one-coat potential. For trim, doors, and cabinets, ProClassic is hard to beat with its smooth, hard acrylic-alkyd finish.
What is the best Sherwin-Williams paint for exterior?
Duration Exterior is the sweet spot. It has a flexible coating that resists cracking and peeling in temperature swings, plus a lifetime limited warranty. Emerald Exterior adds better UV and fade resistance for walls that get heavy sun exposure. SuperPaint Exterior works fine for areas with less weather exposure. A-100 is the budget pick for fences, sheds, and rental properties where premium durability is not a priority.
How much paint do I need for a 12x12 room?
A standard 12x12 room with 8-foot ceilings has roughly 384 sq ft of wall area (4 walls × 12 ft × 8 ft). Subtract a door (~21 sq ft) and two windows (~30 sq ft) and you get about 333 paintable sq ft. With SuperPaint at 400 sq ft/gal and 2 coats, you need 2 gallons (1.83 gal rounded up). That runs about $90-$120 for paint, or $150-$190 if you include a coat of primer.
Should I buy 5-gallon buckets or individual gallons?
Five-gallon buckets save 10-15% per gallon and guarantee color consistency across the batch. Buy buckets when you are painting multiple rooms the same color or any project needing 5+ gallons. Buy individual gallons when you need small quantities, different colors per room, or want to test the color on a small area first. Either way, box (mix) all your paint together in a clean bucket before rolling to eliminate any can-to-can color variation.
When does Sherwin-Williams have paint sales?
SW runs major sales roughly every 6-8 weeks with 30-40% off retail. The biggest sales are typically in spring (March-April) and fall (September-October). Sign up for SW email alerts or ask your local store when the next sale starts. If you have a contractor account (free to set up with a business license), you get discounted pricing year-round regardless of sales.
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