🎨 Paint Calculator

Calculate how many litres of paint needed for your walls.

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What is a Paint Calculator?

A Paint Calculator works out how many litres of paint you need to cover a room's walls, based on the room's dimensions, the number of coats, and the paint's coverage rate. This is a practical tool for Indian homeowners getting quotes from painters or buying paint tins directly — most brands print a coverage rate in sq m/litre on the tin label, which you can plug straight into this calculator.

Formula

Wall Area (m²) = 2 × (Length + Width) × Height × Number of Coats
Paint Required (Litres) = Wall Area ÷ Coverage Rate (sq m/litre)

The formula treats the room as a rectangular box, sums the perimeter (2 × (L+W)) times the height for total wall surface, then multiplies by the number of coats since each coat needs its own paint. The default coverage rate is 10 sq m/litre — a common mid-range emulsion figure — but enter your tin's exact rate for a more precise result.

Worked Example

For a room 5 m long, 4 m wide, 3 m high, with 2 coats and a coverage rate of 10 sq m/litre:

Wall Area = 2 × (5 + 4) × 3 × 2 = 2 × 9 × 3 × 2 = 108 m²
Paint Required = 108 ÷ 10 = 10.8 litres

So this room needs about 10.8 litres of paint for two coats — typically rounded up to two 4-litre tins plus one 2-litre or 3-litre tin, depending on what pack sizes your brand offers.

How to Use This Calculator

  1. Enter the room's length, width, and height in metres.
  2. Enter the number of coats you plan to apply (2 coats is standard for a fresh finish over primer).
  3. Enter the paint's coverage rate in sq m per litre — check the tin label, or leave the default of 10.
  4. Click Calculate to see the total litres and wall area.

Things to Know

💡 Tip: This calculator counts the full wall area including doors and windows, so for a room with large windows or a big door, you can subtract roughly 1.5-2 m² per standard door/window opening from the result to avoid over-buying paint.
  • Textured or rough (unplastered) walls absorb more paint, so their real coverage rate can be 20-30% lower than the tin's stated figure — factor this in for older constructions.
  • Always buy a little extra (5-10%) for touch-ups after move-in, since exact colour-matching a repeat batch later can be tricky.
  • Pair this with the Flooring Calculator and Tile Calculator for a complete room renovation budget.

📅 Last reviewed: July 2026 · Formulas verified against RBI/SEBI/IT Dept guidelines.