UnitConv

Paint Calculator

Estimate how much paint you need for a room or wall

Paint needed
6.04
L
Liters
6.04
L
Gallons
1.6
gal
Paintable area
30.2
m²
Paintable area30.2 m²

Total surface for 2 coat(s), with doors and windows subtracted.

Formula

Paintable area = wall area − (doors + windows)

Paint = (paintable area × coats) / coverage

Wall area is the room perimeter times ceiling height. Standard openings (about 1.8 m² per door, 1.5 m² per window) are subtracted, then paint is divided by the coverage rate.

What is a Paint Calculator?

A paint calculator estimates how much paint you need to cover a wall or a whole room. Enter the room's length, width and ceiling height (or a known wall area), subtract doors and windows, choose the number of coats and the paint's coverage rate, and the tool returns the volume in liters and gallons. Optionally enter a can size and price to get the number of cans to buy and the total cost. Both metric (m², L, m²/L) and imperial (ft², gal, ft²/gal) units are supported, so it works for a single feature wall or a full repaint.

How to Use

1. Choose metric or imperial units. 2. Pick "room dimensions" to enter length, width and ceiling height, or "wall area" to type the area directly. 3. Enter the number of doors and windows to subtract. 4. Set the number of coats and the coverage rate from the paint tin. 5. Optionally add a can size and price to get cans needed and total cost.

Formula & Definition

Paintable area = wall area − (doors + windows) Paint = (paintable area × coats) / coverage For a room, wall area = 2 × (length + width) × ceiling height. For example, a 4 m × 3 m room with 2.5 m ceilings has 35 m² of wall; minus one door and two windows (about 4.8 m²) leaves ~30 m². At two coats and 11 m²/L coverage that is about 5.5 L of paint.

Interpreting Results

The headline figure is the paint volume in your chosen unit; the liters and gallons cards let you cross-check against tin sizes. "Paintable area" is the surface actually being painted after openings are removed. Coverage varies a lot by product and surface - smooth primed walls reach the higher end, while rough or porous surfaces and dark-over-light color changes use more. When in doubt, round up to the next full can so you are not left short.

Frequently Asked Questions

How much paint do I need? ▾

Multiply the paintable area by the number of coats and divide by the paint's coverage rate. This calculator does it for you and converts between liters and gallons.

How many coats of paint should I apply? ▾

Two coats is standard for an even, durable finish. One coat may suffice for a small color refresh; three are sometimes needed for dramatic color changes or over bare surfaces.

What is paint coverage? ▾

Coverage is the area one liter (or gallon) covers, typically 10-12 m²/L (350-400 ft²/gal) for one coat. Check the tin, as it varies by product and surface.

Should I subtract doors and windows? ▾

Yes - this tool subtracts about 1.8 m² per door and 1.5 m² per window so you do not overbuy. Skip the subtraction if you are also painting frames.

How much extra paint should I buy? ▾

Round up to the next full can and keep a little spare for touch-ups. Buying paint from one batch later may not match the color exactly.

This tool provides general estimates only. Actual coverage depends on the product, surface and application method - always check the manufacturer's instructions.