Tile backer board Calculator: measuring notes and method
Measure each lined surface
Keep wall and floor board types separate. Subtract only areas genuinely left unlined; an opening cut from a board may reduce net area without reducing the number of sheets purchased.
Check the panel arrangement
Joint positions and usable offcut sizes determine whether the area-based count can form the required panel layout.
Formula
Sheets = (area − openings) × (1 + waste ÷ 100) ÷ (sheet length × sheet width), rounded up.
Worked examples in metric and imperial units
Illustrative values match Reset example and stay fixed when you edit the calculator. Both columns describe the same calculation; converted inputs are rounded.
Metric worked example
- Total surface area
- 24 m²
- Openings / excluded area
- 0 m²
- Sheet length
- 2.4 m
- Sheet width
- 1.2 m
- Waste allowance
- 10 %
Sheets to buy: 10
Imperial worked example
- Total surface area
- 258.3339 ft²
- Openings / excluded area
- 0 ft²
- Sheet length
- 7.874 ft
- Sheet width
- 3.937 ft
- Waste allowance
- 10 %
Sheets to buy: 10
Follow the calculation
Lengths in this working are in metres.
- Net area = 24 − 0 = 24 m².
- Area per sheet = 2.4 × 1.2 = 2.88 m².
- Sheets = 24 × 1.1 ÷ 2.88, rounded up. Check the cutting layout separately.
Reviewed 19 October 2026. How calculations are checked · Report a correction