Wall Paint Quantity & Whole Cans

When to use it

Use this metric example for four walls of one rectangular room, all painted with the same product and colour. Enter actual wall dimensions and areas that will not be painted. Prices are simulated USD values, not current quotes; replace them with your own.

Related calculations: Tile Quantities & Full Boxes · Wallpaper Rolls & Material Cost.

Inputs

USD

Calculation method

Net wall area = 2 × (length + width) × height − unpainted area. Divide area × coats by the product’s single-coat coverage, then multiply by 1 + the extra allowance. Round required litres ÷ litres per can up to whole cans. Purchased volume minus planned use is the planned surplus. Multiply whole cans by the can price for the paint-only purchase cost. Units participate in the calculation; round the can count, not the litres. The default gives 36 m², 7.92 L and 2 cans; 10 L purchased leaves a planned 2.08 L surplus.

2 × (4 [Room length m] + 3 [Room width m]) × 2.8 [Wall height m]-3.2 [Unpainted area m²] → Net wall area m²

Net wall area m² × 2 [Coats]/10 [Coverage per coat m²/L] × (1 + 10 [Extra allowance]%) → Planned paint L

ceil(Planned paint L/5 [Can volume L]) → Whole cans

Whole cans × Can volume L → Bought volume L

Bought volume L-Planned paint L → Planned surplus L

Whole cans × 40 [Price per can USD] → Paint purchase USD

Change one input

Change coats from 2 to 3. Planned use rises to 11.88 L and the purchase to 3 cans. Net wall area stays unchanged; purchased volume, planned surplus and cost update together.

Results are displayed to at most two decimal places; later formulas use unrounded values.

Scope and limits

• Four walls, one paint and colour; no ceiling.
• Coverage is for one coat; allowance is added to theoretical use.
• Whole identical cans; excludes primer and labour.

Lengths, height, coverage and can capacity must be positive; coats must be a positive integer. Unpainted area must be nonnegative and less than the full wall area; price and allowance must be nonnegative. The 10% allowance is illustrative, not a recommended loss rate. Coverage depends on the product, surface and application. Do not treat kilograms as litres or combine different paints before rounding. This is not a complete decorating quote or a guarantee of remaining paint.

Resene: estimating paint quantities

Download and import into Calvance to edit the numbers. The canvas does not reject every invalid input; check the stated ranges.

Common questions

Can I use a coverage figure for two coats?

First put it on a single-coat basis, or you will count the coats twice. Use the product label or data sheet.

Does the surplus include the allowance?

The planned use already includes the allowance. Surplus is purchased volume minus that planned use, not a prediction of actual leftovers.

Can I calculate directly on this page?

This page explains the method and example. Download the editable canvas and import it into Calvance to use your own numbers.

How to import your template

We recommend using the latest version of Calvance.

1. Save the file. Choose Download template and save the .calvx file to Files on your iPhone or iPad. From a computer, you can send it to your device with AirDrop.
2. Open Import. In All Canvases in Calvance, tap the add button to open the template screen, then choose Import.
3. Choose the file. Select the saved .calvx file to create your own canvas. Importing uses one canvas from your allowance.
4. Edit and check. Check the results against the worked example, then add your numbers. Duplicate the canvas to keep different versions.

Download .calvx file