Room Renovation Calculator
The flagship calculator: enter a room once and get every renovation material quantity at the same time — floor, walls, paint, wallpaper, laminate and skirting.
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Formula and method
Room dimensions give floor area, ceiling area, perimeter and volume. Wall area is calculated from the room perimeter and height, doors and windows are deducted, and each material quantity is then derived from the net area using its own coverage rate and the shared waste percentage.
One room, several materials, one area to start from
A renovation estimate is a list of materials that share a room but not a rule. Walls lose their openings before paint, the floor gains waste before laminate, and the ceiling is a separate area entirely. Starting from the room's dimensions and applying each rule in turn is what keeps the list coherent.
The biggest single error is using the floor area for the walls. In a normal room the walls are two to three times the floor area, and a paint estimate built on 20 m² instead of 48 m² is not a rounding error, it is half the job.
Deductions that are worth making
Deduct windows and doors from the wall area, but do not deduct them from the flooring or the ceiling. A window is 1.7 m², a door 1.8 m², and in a room with two windows and a door that is over 5 m² of paint not bought — roughly a litre and a half per coat.
Do not deduct a radiator or a shelf: painting behind them is skipped in practice, but the paint for a first coat is mixed by the room, not by the obstacle, and the leftover tin is cheaper than a second trip.
The order of work changes the quantities
If the ceiling is being skimmed, the walls are painted after and the paint quantity includes the dust-damaged areas. If the floor is being replaced, skirting usually comes off and the skirting length goes up because the offcuts cannot be reused.
Write the sequence down before ordering: strip, then services, then plaster, then paint, then floor, then skirting. Each step consumes from the same room and the quantities only add up if the sequence is fixed.
How to measure the inputs
- Measure room length, width and height at the widest and tallest points.
- Count doors and windows, and measure the width and height of each type.
- Note the roll or pack sizes you intend to buy for paint, wallpaper and laminate.
Worked example
Room length 13.12 ft; Room width 16.4 ft; Room height 9.19 ft; Door count 1; Door width 2.62 ft; Door height 6.56 ft; Window count 1; Window width 1.97 ft; Window height 3.28 ft; Waste 10 %; Paint coats (optional) 2; Paint coverage (optional) 86.11 ft²; Wallpaper roll length (optional) 9.84 ft; Wallpaper roll width (optional) 1.64 ft; Laminate coverage (optional) 107.64 ft²; Skirting board length (optional) 6.56 ft → Net wall area: 518.82 ft²
Reference data
| Room, m | Walls minus openings, m² | Paint, 2 coats, l | Laminate packs of 1.8 m² |
|---|---|---|---|
| 3 × 4 | 33.7 | 7 | 7 |
| 4 × 5 | 44.5 | 9 | 12 |
| 5 × 6 | 55.3 | 12 | 18 |
| 6 × 8 | 71.5 | 15 | 28 |
Ceiling 2.7 m, one window and one door deducted, paint at 10 m² per litre, laminate with 5 % waste.
Practical tips
- Measure the room once, carefully, and everything downstream stays consistent.
- Add the doors and windows you want deducted as counts and sizes.
- Use the individual calculators afterwards if you need material-specific waste rates.
Sources
- СП 71.13330.2017 — Изоляционные и отделочные покрытия
- EN 13300 — Paints and varnishes
Checked and updated October 22, 2026