Paint Quantity Calculator — How Much Paint, Primer, Putty & Tiles to Buy From Your Room Measurements
Measure the room, get the shopping list. Every coverage number is shown, cited to the manufacturer document it came from, and yours to override — results are honest min–max ranges rounded up to real tins, bags and boxes.
1 · Rooms & measurements
Net paintable area (walls after door/window deductions, plus any ceilings). Deductions subtract from wall area only — never the ceiling.
2 · Paint system — putty, primer, topcoat
Each layer's product class carries its cited coverage band. Tap any band chip to see the source and override it. Coats are editable — set what your painter actually quotes.
| Layer | Product class (cited band) | Coats | Quantity range |
|---|
Putty coverage is a total-application figure (thin coats ≤ 2 mm as published), so it is not multiplied by a coats count.
3 · Shopping list — real pack sizes
Worst-case need rounded up to real packs (least total volume, then fewest tins, then the largest tin). Buy against the worst case; the best-case figure shows what you might get away with on an ideal surface. Packs: 1/4/10/20 L tins, 5/40 kg putty bags
| Material | Best case | Worst case | Buy |
|---|
4 · Tiles — count, boxes, spares
Sizes are catalogue-cited nominal sizes ; wastage defaults are stated conventions, not published specs . Integer-mm math, one single round-up.
Every coefficient, with its source
All numbers this
app can use. Verified figures were read from the named manufacturer document on the shown date
(originals staged in the repository under sources/). beta
marks a figure that could not be confirmed on an official page — it comes from the named secondary
source or stated convention and should be overridden with the number on your own tin.
your value marks your override, used everywhere it flows.
Honest limits — read before buying
- Coverage bands are manufacturer figures for ideal, properly prepared surfaces — porosity, texture, thinning and application method push real consumption outside the band. Buy against the worst-case figure and treat every output as an estimate, not a guarantee.
- Coefficients were verified on the shown date from the named documents; manufacturers reformulate and re-spec. Every value carries its verified-on date and can be overridden in one tap.
- Quantities only, never prices — rates vary by market, dealer and day; the shop's bill is the price.
- Suggested door/window sizes and tile-wastage percentages are stated conventions — measure your own openings; complex or diagonal lays can exceed the cited wastage.
- This is not a site survey: dado heights, damaged plaster, extra putty coats and repair quantities are contractor judgment calls this app cannot make and does not fake.
- Projects live only in this browser's localStorage — clearing site data erases them; print/CSV/JSON export is the only backup.