🎨 Roof Coating Cost Calculator
Calculate gallons of coating, pails, and cost
Painting or coating a roof? Enter your roof area, number of coats, and coverage rate. We'll calculate gallons of roof paint or coating, pails to buy, and estimated cost.
Smart Roofing Calculator — Roof Coating Cost Calculator — smartroofingcalculator.com/coating-calculator/ — printed
Total roof surface area
2 coats recommended
50–100 sq ft/gal typical
10% for texture and overlaps
$25–$50/gal typical
🛒 Materials for this job
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🎨 Apply roof coatings in 50–90°F weather for best adhesion.
🛠️ How This Calculator Works
This calculator multiplies roof area by number of coats, adds waste, then divides by coverage per gallon to get total gallons. It rounds up to the nearest 5-gallon pail for purchasing.
📐 Formula
Gallons = (Area × Coats × (1 + Waste%)) ÷ Coverage/Gallon | Pails = ⌈Gallons ÷ 5⌉📝 Example Calculation
For a 2,000 sq ft roof with 2 coats at 75 sq ft/gal: • Total coverage: 2,000 × 2 = 4,000 sq ft • With 10% waste: 4,400 sq ft • Gallons: 4,400 ÷ 75 = 59 gallons • Pails: 12 five-gallon pails • At $35/gal: ~$2,065
💡 Pro Tips from Roofers
- Pressure wash and repair all cracks/seams before coating.
- Apply primer on bare metal or heavily weathered surfaces.
- Use a squeegee or spray rig for uniform thickness.
- Apply at least 20 mil wet thickness per coat (40+ mil total).
- Allow 24–48 hours between coats for proper curing.
❓ Frequently Asked Questions
How much does roof coating cost?
Roughly $1.25 to $3.00 per sq ft installed by a contractor and $0.50 to $1.25 per sq ft in material if you apply it yourself. A 2,000 sq ft roof therefore runs about $2,500 to $6,000 installed or $1,000 to $2,500 DIY; silicone sits at the top of each range and acrylic at the bottom.
How many gallons of roof coating do I need?
Most elastomeric coatings cover 50–100 sq ft per gallon per coat. For two coats on a 2,000 sq ft roof, you'll need 40–80 gallons depending on the coating and surface texture.
How long does roof coating last?
Quality elastomeric coatings last 10–15 years. Silicone coatings can last 15–20 years. Acrylic coatings last 5–10 years. Recoating before failure extends roof life indefinitely.
Can I coat a shingle roof?
Yes, but use a coating specifically designed for shingles (usually acrylic elastomeric). It seals minor leaks, reduces granule loss, and can lower cooling costs. It won't restore severely damaged shingles.
What is the labor cost for roof coating per square foot?
About $0.75–$1.75 per sq ft. That is the gap between a contractor's installed price ($1.25–$3.00 per sq ft) and the coating alone if you apply it yourself ($0.50–$1.25), and it pays for cleaning, repairs to seams and flashings, primer where needed, and spraying or rolling to the specified thickness.
What type of roof coating should I use?
Acrylic: best value, good UV resistance (not for ponding water). Silicone: best for flat roofs with ponding. Polyurethane: best adhesion and impact resistance. Asphalt emulsion: cheapest, for temporary repairs.
How much roof coating do I need per square foot?
At 20 wet mils per coat, one gallon covers about 80 square feet, so a 100 sq ft area needs about 1.25 gallons per coat. Thicker specifications need proportionally more.
How much does roof coating cost per square foot?
About $1.25 to $3.00 per square foot installed by a contractor, and $0.50 to $1.25 per square foot in material if you apply it yourself. Silicone and heavy elastomeric systems sit at the top of each range; the cleaning, repairs and primer a worn roof needs push a quote higher.
How much does a 5-gallon bucket of roof coating cover?
About 400 square feet for one coat at 20 wet mils, or about 200 square feet at the usual two coats. Thicker specifications and rough surfaces cover less, so check the wet mils on the product data sheet.
How do I estimate a roof coating job?
Multiply the roof area by the number of coats and add 10% waste, divide by the coverage per gallon from the product's specified wet thickness, then add primer, repairs, cleaning and labour.
How many gallons of coating for a 2,000 sq ft roof?
About 55 gallons (11 pails) for two coats at 20 wet mils with 10% waste. At 75 sq ft per gallon it is about 59 gallons.
Why does the coating spec sheet list mils?
Because the warranty depends on the dry film thickness. The wet mils per coat, multiplied by volume solids, gives the dry thickness; coverage per gallon follows from it: 1,604 ÷ wet mils.
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About the Smart Calculator Team
We build free, accurate construction calculators for homeowners and contractors. This article is part of our roofing knowledge base — we also publish guides and tools for other home improvement projects:
Shopping for someone? See our gift guide for roofers & DIY homeowners.
Roof coating cost per square foot
A contractor charges about $1.25 to $3.00 per sq ft installed, which covers cleaning, seam and flashing repairs, primer and two coats. The material alone is the calculator's own arithmetic: two coats at 75 sq ft per gallon plus 10% waste is about 0.03 gallon per sq ft.
| Coating | Price per gallon | Material per sq ft | 1,000 sq ft (30 gal) | 2,000 sq ft (59 gal) |
|---|---|---|---|---|
| Acrylic elastomeric | $20–$30 | $0.59–$0.88 | $600–$900 | $1,180–$1,770 |
| Silicone | $35–$55 | $1.03–$1.61 | $1,050–$1,650 | $2,065–$3,245 |
Silicone costs more per gallon but handles ponding water; acrylic is the value choice on sloped or well-drained roofs. Labor adds about $0.75 to $1.75 per sq ft. Enter your own pail price above for an exact figure.
Worked examples updated . Every figure below is computed with the same formulas as the calculator.
Where coverage per gallon comes from
A US gallon is 231 cubic inches. Spread one mil (a thousandth of an inch) thick, it covers 1,604 square feet. So coverage per gallon is 1,604 divided by the wet thickness in mils — which is why a coating's spec sheet states a thickness, and why the coverage figure you enter in the calculator should come from it.
| Wet thickness per coat | Coverage per gallon | Gallons per 100 sq ft per coat |
|---|---|---|
| 10 mils | 160 sq ft | 0.62 |
| 15 mils | 107 sq ft | 0.94 |
| 20 mils | 80 sq ft | 1.25 |
| 25 mils | 64 sq ft | 1.56 |
| 30 mils | 53 sq ft | 1.87 |
Dry thickness is lower than wet, because the solvent or water evaporates: multiply wet mils by the product's volume solids. Rough surfaces — granulated cap sheet, spray foam, weathered shingles — take more material than smooth metal or single-ply for the same film.
Roof coating estimate, worked through
Worked example: A 2,000 sq ft metal roof, two coats at 20 wet mils
- 20 wet mils per coat is 1,604 ÷ 20 = 80 sq ft per gallon; the calculator uses 80.
- Two coats with 10% waste: 2,000 x 2 x 1.10 = 4,400 sq ft of coverage.
- 4,400 ÷ 80 = 55 gallons, or 11 five-gallon pails.
- At $25-$50 per gallon: $1,375 to $2,750 in coating alone.
Add primer where the manufacturer calls for it (bare or rusted metal, some single-ply), seam and fastener treatment, and cleaning. On a contractor quote, labour and access are usually the larger half.
Worked example: A 1,000 sq ft flat roof at 75 sq ft per gallon per coat
- Two coats with 10% waste: 2,200 sq ft of coverage.
- 2,200 ÷ 75 = 30 gallons, 6 pails.
30 gallons. For a roof that ponds water, pick a coating rated for ponding (usually silicone) — see how roof coatings compare.
- Cleaning: pressure washing and a cleaner to remove chalking and dirt so the coating bonds.
- Repairs: seams, blisters, fasteners and flashings fixed and reinforced with fabric before coating.
- Primer: required on some substrates; it is its own line item in gallons.
- Coats: two is standard; a single thick coat rarely reaches the rated dry thickness evenly.
- When the roof is too far gone to coat, compare the flat roof calculator for replacement.
Painting the walls too? The exterior paint calculator works out gallons of house paint by surface and coats.
Replacing a worn flat roof instead of coating it? The EPDM rubber roof calculator lays out the sheets and counts adhesive pails and seam tape.
Low-slope shed or garage? The rolled roofing calculator counts rolls for single or double coverage down to 1/12.
Gallons worked out? Choose the product from our roof coating picks.
RV roof past recoating? The RV roof replacement cost calculator prices a new membrane.
Roof too far gone to coat? The torch down roof cost calculator prices a new modified bitumen roof.
· Reviewed by the Smart Roofing Calculator editorial team