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Paint Quantity Calculator — Litres & Gallons

Paint coverage is a product value, not a universal constant. Enter room dimensions, the area of openings, coat count and the coverage printed on the chosen paint. Select metres with square-metres-per-litre coverage or feet with square-feet-per-US-gallon coverage. The calculator shows net wall area and rounds only the displayed planning quantity, leaving surface preparation and pack size to the product sheet.

No account Formula visible Your rate and units

Use your evidence

What to have beside you

Use the current bill or tariff sheet, exact product label, location-specific solar estimate, or measured project dimensions. Example physical values teach the tool; zero money rates prevent an unsourced price from becoming a default claim.

USUSA GBUK AUAustralia AEUAE CACanada EUEU NZNew Zealand SGSingapore

Enter your details

Your values

Every input includes a simple explanation.

Simple wordsFormula shownPrivate inputs

Simple viewUsing editable example assumptions for technical settings.

Dimension and coverage systemUser-entered value — example shownThe measurement unit used for the dimensions you are entering.

Room lengthUser-entered value — example shownThe end-to-end measurement of the wall, room, slab, bar, or surface.

Room widthUser-entered value — example shownThe side-to-side measurement of the room, slab, tank, or surface.

Wall heightUser-entered value — example shownThe bottom-to-top measurement of the wall or room.

Doors and windowsUser-entered value — example shownThe combined area of doors, windows, or other gaps to subtract.

m²

Number of coatsUser-entered value — example shownHow many complete layers of paint you plan to apply.

coats

Product coverageUser-entered value — example shownThe surface area covered by one litre or gallon for one coat, taken from the product sheet.

m²/L

Private: calculations run in your browser; a saved scenario stays on this device.

Your result

Estimated paint

9.37 L

The product's coverage value is applied to the net wall area for every coat, then the allowance is added.

Net wall area44.6 m²

Gross wall area48.6 m²

Coated area89.2 m²

Preliminary quantity only. This result is not structural design, reinforcement approval or a safety instruction.

How this was calculated

Formula used

Net wall area = 2 × (length + width) × height − openings; paint = net area × coats ÷ product coverage × allowance

Your values in the formula

44.6 area × 2 coats ÷ 10 coverage × allowance = 9.37 L

Assumptions and rounding

Coverage and dimensions must use the selected system.
Primer, texture and package rounding are not automatically added.

Porosity, texture, colour change, application method and product instructions affect coverage. Primer is not included unless its own coverage is entered separately.

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What the result means

Use it as a scenario

Porosity, texture, colour change, application method and product instructions affect coverage. Primer is not included unless its own coverage is entered separately.

A 5 m × 4 m room with 2.7 m walls has 48.6 m² of gross wall area before openings are subtracted.

What can change