How Much Paint Do I Need? Thai Paint Can Sizes and Coverage
Figures reviewed 14 October 2026
Thai paint can sizes
Paint in Thai shops is commonly labelled in US-gallon sizes alongside litres. The coverage below comes from TOA’s published one-coat example:
| Can | Litres | Covers per coat (approx.) |
|---|---|---|
| ¼ gallon (quart) | 0.946 L | 8–9 m² |
| 1 gallon | 3.785 L | 30–35 m² |
| 2.5 gallons | 9.46 L | 75–80 m² |
| 5 gallons | 18.93 L | 150–160 m² |
That example works out to roughly 8.5 m² per litre per coat. Coverage varies by product and surface; check the actual paint label, especially for textured, exterior or primer paint.
TOA describes shop tinting for its cited 1-gallon and 2.5-gallon products; other products and 5-gallon colour options may differ. Check the chosen paint and colour system with the shop before buying several cans.
The formula
Wall area = perimeter × height = 2 × (length + width) × height
Net area = wall area − doors − windows
Litres = net area × coats ÷ coverage per litre × (1 + waste %)
Round up to whole cans
Example: bedroom 4 × 6 m, 2.6 m ceiling
Wall area = 2 × (4 + 6) × 2.6 = 52 m²
Subtract 1 door (0.9 × 2 m = 1.8 m²) and 1 window (1.2 × 1.2 m = 1.44 m²) → 48.76 m²
For this worked example, use 8.5 m²/L per coat: 48.76 × 2 = 97.52 m² ÷ 8.5 = about 11.47 L before waste. The calculator’s editable starting value is 8.5 m²/L; check the actual paint label before buying.
Add 10% for waste → 12.6 L
Manual buying option: one 2.5-gallon can plus one 1-gallon can gives 13.245 L, or four 1-gallon cans give 15.14 L. The calculator compares one selected tin size at a time.
The ceiling isn't included. Calculate it separately (4 × 6 = 24 m²), because ceiling paint is often a different product.
Before you buy
Primer: new plaster, repairs and strong colour changes need primer, calculated separately.
Exterior walls: use paint rated for exterior use. Thai sun and rain break down interior paint quickly.
Same batch: buy all the paint for one room at the same time, with the same colour code and base.
Painter's quotes: check whether paint is included, how many coats are quoted, and whether surface preparation is included.
FAQ
Can I paint my rental? Check your lease and get the landlord's agreement in writing first. Many leases require you to return the walls to their original colour.
Why does my estimate differ from the shop's? Shops often quote one coat, or no waste allowance. Compare using the same number of coats.
Estimate paint for a 4 × 6 m bedroom