This page estimates paint quantity, not the full repaint bill of materials
Paint planning goes wrong when the user thinks only in terms of room count and forgets coverage, number of coats, and openings such as doors or windows. A useful paint calculator needs to make those assumptions visible instead of returning one mysterious litres figure.
This page estimates paint quantity from paintable wall area, coverage per litre, number of coats, and deduction area. Use it to plan purchases for a room, flat, or small project before you finalise primer, putty, and labour.
What this estimate helps you budget
- Estimates litres of paint required from wall area, coverage rate, coats, and deduction area.
- Shows net wall area and a rough bucket estimate for purchase planning.
- Helps compare one-coat and two-coat scenarios without rewriting the whole calculation.
Where this estimate stops
- It does not separately calculate primer, putty, texture paint, or labour.
- It does not automatically include ceiling area unless you add it into the paintable area yourself.
Litres required, can-size rounding, and buffer
The page first calculates net paintable area by subtracting deduction area from total wall area. It then multiplies net area by the number of coats and divides by coverage per litre to estimate litres required.
Real purchase decisions usually need a small buffer for touch-ups, wastage, and uneven surfaces. This page gives the base quantity clearly so you can decide how much extra margin to add before buying common can sizes.
Examples
One room repaint
- Area and coats: Single room wall area, 2 coats
- Deduction: Doors and windows excluded
This is the most common use: estimate litres before you visit the paint dealer or compare brands.
Full flat estimate
- Area and coats: Combined wall area across rooms
- Goal: Rough total litres before purchase planning
Use the bucket estimate to judge how many standard cans you may need rather than relying only on litres with no packaging context.
How to use this Paint Calculator
- Enter the total paintable wall area.
- Enter the expected coverage per litre from the paint product or your working estimate.
- Add the number of coats and deduct doors and windows if you do not plan to paint them.
Common mistakes
- Forgetting to multiply by the number of coats.
- Ignoring door and window deductions when the openings are large.
- Using one coverage figure for all brands, textures, and wall conditions.
Edge cases and limitations
- Highly absorbent or damaged surfaces can increase actual paint consumption materially.
- Exterior and interior paints often have different practical coverage behaviour.
What is not included
- Primer, putty, texture coats, and labour.
- Ceiling area unless you include it manually.
- A guaranteed dealer can-size plan or final site wastage.
Methodology and review basis
Built and reviewed by Atul Sharma • Last updated 2026-03-22
This page uses a straightforward coverage model: net paintable area times coats divided by coverage per litre. It is intended for purchase planning, not as a final contractor consumption certificate.
Site-wide review standards live in the review methodology and sources policy.
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Questions that come up during planning
- Should I include wastage?
- Yes, for real purchase planning. This page shows the base quantity first so you can add a sensible buffer yourself.
- Does this include primer or putty?
- No. It estimates paint quantity only unless you manually model those layers elsewhere.
- How many coats should I assume?
- Two coats are common for many repaint jobs, but the correct answer depends on the product, colour change, and wall condition.
- Is interior coverage the same as exterior coverage?
- Not necessarily. Product type and surface condition can change real coverage materially.
- Should I include the ceiling?
- Only if you want ceiling paint included in the same total. Otherwise leave ceiling area out of the paintable-area input.