We use cookies.This website uses essential cookies to operate core features. With your consent, we also use analytics cookies to understand traffic and improve the service. For more details, see our .
We use cookies.This website uses essential cookies to operate core features. With your consent, we also use analytics cookies to understand traffic and improve the service. For more details, see our .
Was this tool helpful to use?
Your feedback helps us make it better
Input room dimensions and doors/windows room by room, automatically calculate area and estimate tile, paint, and other material quantities
Default door size 0.9m × 2.0m (1.8m²); enter total window area
Enter at least one room's length and width to calculate
Overview
Understand what the tool solves, how it works, and the boundaries of its data.
Enter each rectangular room’s length, width, and height in meters. The calculator totals floor area (square meters), perimeter (meters), volume (cubic meters), gross wall area, net wall area after openings, and skirting length. The inputs are metric only; convert feet and inches to meters before entering them. For example, 12 ft is about 3.66 m and 10 ft is about 3.05 m, so a 12-by-10-ft room can be entered as approximately 3.66 by 3.05.
For a rectangular room, floor area = length × width; perimeter = 2 × (length + width); volume = floor area × height; gross wall area = perimeter × height. Net wall area subtracts 1.8 m² per door and the total window area, with a floor of zero. The calculator also estimates 600, 800, or 1,000 mm square tiles with 8% added waste; wallpaper at 5.3 m² per roll with 10% added; and paint at 10 m² per liter per coat, rounded up to 5-liter cans for the selected one to three coats. These are fixed calculator assumptions, not product guarantees.
Guide
Follow the workflow and verify inputs and outputs with practical examples.
Record wall-to-wall length, width, and height, then convert every linear measurement to meters. Enter the same unit consistently so area and volume results have meaningful units.
Enter the number of doors and the combined area of the windows in square meters. The model subtracts a fixed 1.8 m² for each door; it does not accept individual door dimensions.
Select a listed tile side length and one, two, or three paint coats. Add rooms separately when you want a whole-home total.
Compare floor and net wall areas before using the tile, wallpaper, paint, or skirting estimates. Check the built-in assumptions against the actual product package and room features.
A 4.5 m × 3.2 m × 2.8 m room has 14.4 m² of floor area and 43.12 m² of gross wall area. With one door and 2.25 m² of windows, net wall area is 43.12 − 1.8 − 2.25 = 39.07 m². For 800 mm tiles, the estimate is ceil(14.4 × 1.08 ÷ 0.64) = 25 tiles. Two paint coats give 39.07 × 2 ÷ 10 = 7.814 liters, rounded up to two 5-liter cans.
Use cases
See how the tool fits into real work and everyday tasks.
A homeowner can enter each rectangular room and compare floor and wall totals before discussing scope with a contractor.
A shopper can choose tile size and paint coats to get a starting quantity, then check the result against package coverage, layout, and installer advice.
A project manager can review the calculator’s net wall area alongside a quote and ask whether both use the same door, window, ceiling, and room-boundary assumptions.
Q&A
Find concise answers to common questions and confusing cases.
No. Enter meters for length, width, and height, and square meters for window area. Convert U.S. customary measurements before entering them.
No. It subtracts a fixed 1.8 m² per door. If the opening differs, treat net wall area as an estimate and adjust it using measured dimensions.
The formulas assume rectangular rooms. Split an irregular space into non-overlapping rectangles and enter each part separately, taking care not to count shared areas twice.
Tile waste, wallpaper coverage, paint spread, coats, and package size are simplified fixed inputs. Surface texture, pattern matching, cuts, and product instructions can change what a real project needs.
Notes
Review scope, result limitations, and important precautions before use.
The calculation assumes rectangular rooms and fixed door, waste, coverage, roll, and can values. It does not model alcoves, angled walls, sloped ceilings, pillars, layout cuts, surface condition, or product-specific coverage. Verify on-site dimensions, labels, and installation guidance before ordering materials or starting construction. A contractor’s measured scope may use a different convention.
Related
Discover related tools, collections, and available API capabilities.