5 min read
Paint Coverage Guide: How Far Does a Litre Really Go?
Every paint can promises a coverage rate — and every wall seems to drink more than promised. This guide explains what coverage rates really mean and how to buy the right amount the first time.
What the coverage number on the can means
The “10 m² per litre” on the label is measured on smooth, sealed, previously painted surfaces under lab conditions. Real walls differ: bare plaster can halve coverage, textured render can cut it by a third, and dramatic colour changes need an extra coat.
Use the label rate as the best case. For new drywall or plaster, plan on the primer rate (8 m²/L) for the first coat even when using paint with primer claims.
Measure once, paint once
Coverage math starts with honest wall area: 2 × (length + width) × ceiling height, minus doors and windows. The Wall Area Calculator does this in seconds and deducts standard openings automatically.
Then apply the formula: net area × coats ÷ coverage rate. The Paint Calculator chains both steps and converts the result into cans you actually buy.
Two coats are not optional
The first coat seals and evens the surface; the second delivers the colour you chose. Skipping the second coat leaves patchy sheen that shows in raking light — the most common DIY paint complaint.
The exception: premium one-coat paints over a similar existing colour. Dark over light (or light over dark) always needs two coats, sometimes three over deep reds and blues.
Buying strategy
Buy all cans from one batch — the batch number is printed on the label, and tint varies slightly between batches. If the job needs 7.1 litres, buy 7.5 or 10 litres, not 7: running out mid-wall leaves a visible seam.
Keep a sealed half-litre for touch-ups. Walls get scuffed; having the exact batch on hand makes repairs invisible.