How to Estimate Woodwork Trim and Door Paint
Skirting boards, architraves, window sills, and doors are never coated in standard wall paint — they need a durable enamel finish (like Dulux Aquanamel or Taubmans equivalents) in Gloss, Semi-Gloss, or Satin sheen, rated to withstand knocks and scuffs.
Converting Trim Profiles to Surface Area
- Skirting Boards: Multiplying total linear metres by 0.1m accounts for the face profile and top bevel curve of a standard 67–92mm skirting board.
- Internal Doors: Both faces plus the surrounding architrave equates to approximately 4.0m² of coverage per door.
- Window Frames & Sills: Roughly 1.2m² per standard window.
Coverage Rates & Primer
Premium enamel trim paint is rated at 14–16m² per litre per coat, confirmed directly against Dulux's own published technical finishing schedule. Bare or new timber needs a dedicated primer coat first, at a notably lower coverage rate of roughly 7.3–10m² per litre — primer needs a thicker film build for proper adhesion, which is why it doesn't stretch as far as the topcoat.
Frequently Asked Questions
Primer is applied at a thicker film build specifically to achieve good adhesion to bare timber, which naturally means it covers less area per litre than a topcoat designed to flow out thin and smooth.
Not recommended. Standard wall paint isn't formulated for the durability, wipeability, and knock-resistance that high-traffic trim, doors, and skirting need. Dedicated enamel trim paint is worth the extra cost for these surfaces.
Trim work involves far more cutting-in, brush loading, and painting into profile curves and bevels than a flat wall, which uses more paint proportionally for the same area — the higher waste allowance reflects that.
Water-based enamels (like Dulux Aquanamel) are easier to clean up, don't yellow over time, and dry faster, but can be trickier to get a fully smooth finish with. Oil-based enamels traditionally self-level better and are often preferred for the smoothest possible finish, at the cost of stronger fumes and longer dry times. Both are valid choices — coverage rates in this calculator apply to either.