Fence Paint / Stain Calculator
Calculate how much paint or stain a fence needs, including the posts.
Five product types, one or two sides, and a 12% waste allowance included.
Fence paint coverage calculation ensures you buy the right amount of paint or stain for your project without multiple trips to the store. Fence boards have a surprisingly large surface area when both sides and edges are counted.
The Formula:
Total area = (Fence length × Height × Sides) + (Post width × Height × 4 faces × Number of posts)
Paint needed = (Total area × Coats × 1.12 waste) / Coverage rate per tin
Coverage Rates by Product:
| Product Type | Coverage per liter | Coverage per gallon |
|---|---|---|
| Exterior wood paint | 9 m² | 367 sq ft |
| Fence sprayer application | 7 m² | 285 sq ft |
| Wood stain / preservative | 6.5 m² | 265 sq ft |
| Decking oil | 5 m² | 204 sq ft |
| Stain on rough-sawn or weathered wood | 4 m² | 163 sq ft |
Those figures span more than two to one from top to bottom. Choosing the row that matches what is actually in your tin matters more than measuring the fence carefully, and it is the reason most people end up going back for another tin.
Waste Factor: This calculator adds 12% for laps, spills, and board texture variation. Rough-sawn boards drink more than that, but the rough-wood coverage row already accounts for it, so do not double up.
Worked Example:
Fence: 20 m long, 1.8 m high, painted both sides, 20 wooden posts (each 10 cm square × 1.8 m tall), two coats of exterior wood paint.
- Board area (both sides): 20 × 1.8 × 2 = 72 m²
- Post area: 20 × (0.1 × 1.8 × 4 faces) = 20 × 0.72 = 14.4 m²
- One coat: 72 + 14.4 = 86.4 m²
- Two coats: 86.4 × 2 = 172.8 m²
- With 12% waste: 193.5 m²
At 9 m² per liter: 193.5 ÷ 9 = 21.5 liters. Buy 22 liters.
The posts are 17% of that job. Leave them out, as most fence calculators quietly do, and you finish the boards with an empty tin and a row of bare posts.
Practical Tips:
- Apply preservative first on new or bare wood. Paint alone doesn’t protect against rot
- Never paint wet or damp wood. Moisture trapped underneath causes peeling within months
- A garden sprayer cuts application time by 60% vs brush, but requires masking nearby plants
- Semi-transparent stains last 3–5 years; opaque paint lasts 5–7 years but hides natural grain
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
SuperGlobalCalculator is independently built and maintained. See how we build and verify our calculators.