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Renovation Quantity Calculator

Enter room dimensions and waste rate to estimate tiles, flooring packs, paint buckets (two coats, 12 square meters per liter) and wallpaper rolls, with wall area and door/window deductions computed locally.

Buying materials for a renovation fails at both extremes: too little means work stops waiting for a resupply that may not match the batch, and too much means boxes stacked on the balcony with nothing to return them to. The quantities follow rules — floor area divided by the size of one tile, plus a margin, gives the tile count; paint needs the wall and ceiling area worked out first, minus doors and windows, then converted into litres for two coats.

The waste rate is the parameter beginners most often miss: 5–8% covers a straight lay, diagonal or patterned work starts at 10%, and wallpaper matching a pattern loses more again. This tool defaults to 8% and it can be adjusted for the laying pattern; every quantity is rounded up, since a spare tile is better than a gap.

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How to use

  1. Enter the room dimensions.
  2. Adjust the waste rate for the laying pattern.
  3. Read the tile, flooring, paint and wallpaper quantities.
  4. Check the wall area after deducting doors and windows.

How it works

How to choose the waste rate

Waste comes from cutting scraps and breakage: straight-lay (horizontal/vertical) cuts are neat, so 5-8% usually suffices; 45-degree diagonal lay and herringbone patterns produce many fragments, starting at 10-15%; irregular spaces (a living room with many pillars) add 2-3%. For a first renovation, take the upper bound — the leftover whole pieces usually can be returned.

How paint liters are converted

Paint follows a "two coats of topcoat" convention: painted area x 2 divided by coverage per liter (a conservative 12 m²/L). Products labeled 13-15 m²/L are ideal-conditions figures; rough walls absorb more, so 12 is closer to reality. Divide the result by 18 L and round up to cans; the leftover half-can is just right for touch-ups.

How to deduct door and window openings

Painted area = ceiling + four walls - door/window openings. The tool defaults to 2 m² per door and 1.8 m² per window, with editable counts; bay windows and openings can be converted into corresponding counts. Wallpaper likewise uses wall area minus openings plus waste.

Can surplus material be returned

Whole boxes of tiles and whole packages of flooring are generally returnable (keep the packaging and receipts), but loose pieces aren't — exactly why the tool rounds up by whole packages. Opened paint can't be returned, so buy by the can count first and add a small can if short; keep the color code in the order, since reordering the same color code and batch minimizes color difference.

Code example

JavaScript Tiles and flooring: area × waste / unit area, rounded up 

const area = 4 * 5;                                   // 20 m²
const tiles = Math.ceil(area * 1.08 / (0.8 * 0.8));   // 800×800 tiles, 8% waste → 34 pieces

// Wood flooring is sold by the pack: / area per pack (2.2 m² default), rounded up
const packs = Math.ceil(area * 1.08 / 2.2);           // 10 packs

JavaScript Paint: the area to cover and two-coat volume 

const paintArea = top + wall - openings;   // ceiling + four walls - door and window openings
// A door counts as 2 m² and a window as 1.8 m²; for a 4×5×2.8 room with one of each:
// 20 + 2×(4+5)×2.8 - (2+1.8) = 66.6 m²

const liters = paintArea * 2 / 12;         // two coats, about 12 m² per litre (per coat) → 11.1L
const buckets = Math.ceil(liters / 18);    // 18L per bucket → 1 bucket

FAQ

How many 800x800 tiles for a 20 m² living room?

Each tile is 0.64 m², so 20 m² with 8% waste is about 33.75, rounded up to 34 tiles. The installer may fine-tune by layout, so 34-36 is a reasonable range, and surplus whole tiles are returnable.

Why does floor area per package differ?

Brands differ in pieces per package and plank size, commonly 1.8-2.5 m²/package. This tool defaults to 2.2 m²/package; change "area per package" to the label's figure and the package count recomputes.

How much does 2.6 vs 2.8 m ceiling height change paint use?

For a 5x4 m room, each 0.2 m of ceiling height adds about 3.6 m² of wall, or 0.6 L over two coats — under half a can. Just enter the height accurately; no need to adjust waste for it.

Why is wallpaper counted by the roll, not the square meter?

Wallpaper is sold by the whole roll; a standard roll 10 m x 0.53 m is about 5.3 m², and pattern-matching wastes a lot (a roll actually covers 4-4.5 m²). Counting by the roll matches how it's bought; the more complex the pattern match, the closer waste should be to 15%.

How do I measure an L-shaped living room?

Split it into two rectangles and sum: first the large rectangle by full length and width, then subtract the missing corner (with the same spec and waste). This tool handles one rectangle at a time — run it twice.

What if the tile spec list doesn't have mine?

Pick the closest spec — usage is driven by single-tile area, and 600x1200 and 750x1500 are close, so the difference is small; fine-tune by the actual single-tile area if exact.

Does the computed usage include baseboards?

No. Baseboards are by perimeter: about 2 x (length + width); ceramic baseboards are bought by the meter, wood ones converted to pieces by actual length, plus 5% waste.