How many coats of paint do I need?

For walls in good condition with the same colour: 1 coat. For colour change or highly absorbent walls: 2 coats. For dark over light or vice versa: 2–3 coats + primer.

What is the coverage of interior emulsion paint?

Interior emulsion typically covers 12–14 m²/L per coat. Exterior or textured paint covers less, around 8–10 m²/L.

How is paint calculated for ceilings?

Measure length × width of the ceiling in metres. Apply the paint coverage (10–14 m²/L) and number of coats. For textured ceilings, use 20 % more paint.

Paint Coverage Calculator

Last updated: 2026-06-23

Use the Paint Coverage Calculator to get instant, accurate results. Enter your values below.

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Enter values and press Calculate

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Common Sizes — Click to Fill

Wall length (m)	Wall height (m)	Number of coats (pcs)	Paint type	Doors & windows area (pcs)
10 m	2.5 m	2 pcs	1	2 pcs
12 m	2.5 m	2 pcs	1	3 pcs
14 m	2.7 m	2 pcs	1	3 pcs
16 m	2.7 m	2 pcs	1	4 pcs
20 m	3 m	3 pcs	1	4 pcs

What is the Paint Coverage Calculator?

A common DIY mistake is buying paint by guessing — either running short halfway through the second coat or ending up with cans you'll never use. This calculator measures the paintable wall area, subtracts doors and windows, and divides by your paint's coverage rate per litre to give you an exact purchase quantity by number of coats.

You may also find the Wallpaper Calculator, Backsplash Tile Calculator, and Crown Molding Calculator useful.

Who Uses This Calculator?

This tool is used by homeowners painting a room, professional painters quoting jobs, and property managers budgeting for interior refreshes.

How to Use the Paint Coverage Calculator

Enter your Wall length.
Enter your Wall height.
Enter your Number of coats.
Enter your Paint type.
Enter your Doors & windows area.
Click Calculate to see your results instantly.

Formula

The calculator uses the following formula:

Paintable area = (perimeter × height) - doors_windows; Litres = area × coats ÷ coverage_per_litre

Worked Example

A 5 m × 4 m room with 2.7 m ceilings, 2 coats, one door, and two windows has about 43 m² of paintable surface. At 12 m²/litre coverage: 3.6 litres needed, so buy two 2-litre tins.

Step-by-Step Calculation

Total wall area: 4 × 14 m × 2.5 m = 140 m² (for a square room — adjust for actual perimeter)
Subtract doors/windows: 3 × 2 m² = 6 m² → 134 m² paintable
Standard paint: 10-12 m²/litre; 2 coats: 134 × 2 ÷ 11 = 24.4 litres
5L cans: ceil(24.4 ÷ 5) = 5 cans

Common Mistakes to Avoid

Using the floor area instead of the wall area
Forgetting that dark colours or stained walls need 3 coats instead of 2
Not accounting for texture — rough or porous walls absorb 20-30% more paint

Pro Tip: Dark colours and reds typically need 3 coats for full coverage, not 2. If you are painting dark over light or changing colour dramatically, use a tinted primer first — it reduces the number of topcoats needed.

Frequently Asked Questions

What is standard paint coverage per litre?

Most interior wall paints cover 10–14 m² per litre per coat. Quality paints are often at the higher end (13–16 m²/L). Exterior paints cover 8–12 m²/L. Primers typically cover 8–12 m²/L. Always check your specific product's data sheet.

Do I need to subtract doors and windows from my paint calculation?

Yes — a standard door is about 1.8 m² and a window 1.5 m². This calculator lets you enter the number of each and deducts them automatically. Skipping this step overestimates paint by 10–20% in a typical room.

How many coats of paint should I apply?

Two coats are standard for most interior repaint jobs. New plasterboard or a drastic colour change may need 3 coats. One coat is sufficient only for touch-ups or very similar colour-on-colour.

Should I paint walls or ceiling first?

Always paint the ceiling first, then walls from top to bottom. This way any drips or spatters on the wall get covered when you paint the wall. Paint skirting boards last.

How do I calculate paint for a room with vaulted ceilings?

For a triangular vault, add (0.5 × width × height of triangle) to the rectangular wall area below. For a curved vault, measure the arc length and multiply by the room length.

Written and reviewed by the CalcToWork editorial team. Last updated: 2026-06-23.