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Paint Calculator
m²
coats
Paint Calculation Formula
Paint Required: (Wall Area × Number of Coats) / Coverage Rate
Paint + Waste: Paint Required × 1.1
Paint + Waste: Paint Required × 1.1
Paint Calculator — Walls, Ceilings & Trim
Material waste accounts for 10–15% of total construction costs on Australian sites (Master Builders, 2025). Calculating paint quantities accurately eliminates unnecessary spend and reduces job-site waste.
Paint Coverage Rates
| Paint Type | Coverage (m²/L) | Typical Coats | Litres per m² |
|---|---|---|---|
| Ceiling Flat | 12–14 | 2 | 0.15 |
| Interior Low Sheen | 12–16 | 2 | 0.14 |
| Interior Semi Gloss | 14–16 | 2 | 0.13 |
| Exterior Acrylic | 10–14 | 2 | 0.17 |
| Trim / Gloss Enamel | 14–16 | 2 | 0.13 |
| Primer / Sealer | 10–12 | 1 | 0.09 |
Quick Reference — Standard Room Sizes
| Room | Wall Area (m²) | Ceiling (m²) | Paint Needed (L) |
|---|---|---|---|
| Bedroom (3m × 4m) | 33.6 | 12 | ~6.5 L |
| Living Room (5m × 6m) | 52.8 | 30 | ~12 L |
| Bathroom (2.5m × 3m) | 15.4 | 7.5 | ~3.5 L |
| Whole House (3-bed) | ~250 | ~120 | ~55 L |
Tips for Accurate Paint Estimating
- Deduct 50% for windows and doors — a standard door is ~1.6 m², a window ~1.2 m².
- Textured walls and bare plaster absorb more — add 15–20% extra.
- Dark-over-light colour changes may need 3 coats instead of 2.
- Always check the product data sheet for actual spread rate.
More than just calculators
Built Simple manages your entire project — estimates, schedules, tasks, and team.