Trim Paint Calculator
Calculate how much paint you need for trim and baseboard from total linear metres. Select trim type — baseboard, door casing, or window trim — for an accurate quantity estimate.
Part of the Surfaces & Finishes calculators — see all tools in this category.
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How it works and assumptions
This calculator estimates trim and baseboard paint quantity by converting linear metres of trim to effective painting area, then applying the standard semi-gloss coverage rate.
- Measure total trim length: Add up all trim runs in linear metres. Include baseboard, door casings, and window trim — enter each as separate calculations if they are different trim types.
- Select trim type: Baseboard (90mm), Door Casing (65mm), or Window Trim (55mm). The trim width determines the effective painting area.
- Set coats and waste: Two coats is standard for trim. A 10% waste factor covers brush loading and touch-ups.
- Review effective area: The results show the effective painting area (linear metres × trim width) so you can verify the calculation makes sense.
Formula: Effective Area = Length × Trim Width. Paint = (Effective Area × Coats) ÷ 9 m²/L × (1 + Waste %)
Note: This calculator uses a fixed semi-gloss rate of 9 m²/L. Trim quantities are much smaller than wall areas — the results will look different from area-based calculators, which is expected.