The amount of paint needed for one room depends on its paintable surface area, planned coats, wall condition and the verified coverage of the selected product. Room length and width alone are not enough because ceiling height and the size of doors and windows change the result.
Use the calculator below to measure wall or ceiling area in feet or metres. It reports paintable area and total coat-area, but it will not convert those figures into litres unless verified, product-specific coverage data is available.
The basic paint-area formula
For a rectangular room, wall area is calculated as 2 × (length + width) × height. Measure openings separately using width × height × quantity, then subtract them from the gross wall area. A ceiling is simply length × width.
Multiply the remaining paintable area by the number of finish coats you plan to apply. For example, a 12 ft by 10 ft room with a 10 ft height has 440 sq ft of gross wall area. After deducting 60 sq ft of openings, the net area is 380 sq ft; two coats correspond to 760 sq ft of coat-area.
This still does not establish the number of litres. Coverage can vary by product, surface texture, porosity, preparation, colour change and application method, so use current coverage information for the exact paint or ask the supplier to confirm quantity.
Ready to measure? Enter the actual dimensions below, select a relevant Triangle Paints product and send the result for quantity guidance.
Interactive planning tool
Calculate your paintable area.
This tool calculates surface area—not litres. Triangle Paints does not currently publish verified product coverage data in this catalogue, so the team should confirm quantity.
Add each room separately and enter doors, windows or other openings you do not plan to paint. The optional allowance is a user-selected planning adjustment, not manufacturer-required wastage. If you are painting ceilings or exterior walls, choose that surface before entering measurements.
Understanding your result
The result separates net paintable area from total coat-area so the mathematics remains visible. New or rough plaster may also require filling, putty, sealer or primer; these materials are separate from finish-paint quantity and should be considered as part of the full painting system.
Triangle Paints lists current pack sizes for many products, but pack size alone cannot determine coverage. Once you have the measured area, planned coats and selected product, send the prepared WhatsApp enquiry so the team can confirm current guidance and availability.
Frequently Asked Questions
How much paint do I need for a 10 × 12 room?
You also need wall height, measured openings, planned coats and verified coverage for the selected product. A floor dimension alone cannot produce a reliable litre estimate.
Should doors and windows be subtracted?
Large openings that will not be painted can be deducted. Measure each opening instead of relying on hidden default dimensions.
Does rough plaster require more paint?
Texture, porosity and preparation can affect usage. Prepare the surface properly and use current coverage guidance for the selected product.
Does primer count as finish-paint quantity?
No. Primer is a separate part of the painting system and should be assessed using its own product guidance.