UtiliMate

Free browser tool

Paint Calculator

Plan one paint product from a known area, a rectangular room or individual walls. Check net area, full coats and whole tins using your product’s stated coverage.

Plan one paint product

Example measurements are pre-filled. Replace them with your own and the exact coverage printed on your paint tin.

Known area
Surface and paint

The example coverage is not a recommendation for any product. There is no automatic allowance; choose one if your surface or supplier requires it.

Whole tins and optional cost

Price and currency are entered by you. No exchange-rate conversion, live prices or delivery costs are included.

Changing units converts valid values automatically. Recalculate after changing an input.

Enter your measurements, then estimate.

Inputs and results stay in this browser. The website’s existing tool-used event contains only this tool’s name, never your measurements or price.

How it works

Estimated paint volume = net area × full coats ÷ coverage, multiplied by your chosen allowance. Tin count rounds the volume up to whole tins; optional cost uses your entered price per tin. Metric and imperial measurements are converted before calculation.

From measurements to whole tins

For a rectangular room, wall area = 2 × (length + width) × height. Include length × width for the ceiling only when using the same paint. For individual walls, add width × height for each one. Subtract your measured doors and windows, multiply by the full coats, then divide by the exact product coverage. Apply your chosen percentage allowance and round the resulting volume up to whole tins of the size you entered.

One foot is 0.3048 metres. A US liquid gallon is 3.785411784 litres; a UK imperial gallon is 4.54609 litres. “Gallon” and currency alone are not enough to identify a volume. NIST conversion factors.

A worked example, not a product quote

A 4 m × 3 m room with 2.5 m-high walls has 35 m² of wall area. Excluding 3 m² leaves 32 m². Two coats at an illustrative 10 m² per litre need 6.4 litres. A user-chosen 10% allowance makes 7.04 litres, so three 2.5-litre tins supply 7.5 litres. Primer, trim, another colour and delivery are separate.

Sherwin-Williams’ planning guidance distinguishes simple and custom projects and notes that product and surface conditions affect quantities. This independent tool does not recommend a specific paint or guarantee coverage.

Three practical tips

  • Use the coverage and coat instructions for the exact product; the pre-filled numbers are examples.
  • Subtract measured openings, and calculate different paints, primer and trim separately.
  • Check surface texture and application guidance with your supplier before ordering.

Does a room estimate include the ceiling, primer or trim?

A rectangular-room estimate includes four walls. Its optional ceiling checkbox adds the ceiling only for the same paint and coverage. Primer, trim, another colour and other products need separate estimates. This is a planning tool, not guaranteed product coverage.