Exterior
Wood stain or varnish quantity
- where
- stain or varnish needed (L)
- timber area (m²)
- number of coats
- spreading rate (m²/L)
- waste allowance (%)
- tins to buy
- tin size (L)
Explain this equation
Works out wood stain or varnish for a job and the tins to buy.
Area times coats divided by the spreading rate gives litres, plus waste; divided by the tin size and rounded up gives tins.
Coverage arithmetic: litres equal area times coats divided by spreading rate.
Sense check: 20 m² in two coats at 15 m²/L with 10% waste is about 2.9 litres, two 2.5 litre tins.
Watch out: sawn timber can take two or three times as much as planed timber, and the first coat on bare wood soaks in more.
Works out wood stain, varnish or oil for cladding, joinery or decking, allowing for smooth or rough sawn timber.
Enter your values to see the result.
Good to know
Sadolin Classic: up to 15 m²/L on smooth planed timber and up to 8 m²/L on rough sawn; 2 coats on new fencing and cladding, 3 on new decking. Rough sawn timber can take nearly twice as much. Use the product’s own data sheet: clear varnishes and oils vary widely.
Common mistake
Using the planed-timber rate on sawn boards and running short halfway along a run, which leaves a visible lap.
Limits
One tin size. End grain and very dry, weathered timber absorb more.
Sources
- Sadolin Classic woodstain data sheet (up to 15 m²/L on smooth planed timber, up to 8 m²/L rough sawn; 2 coats on new fencing and cladding; 1, 2.5, 5 L)
- BS 6150:2019 Painting of buildings. Code of practice
Results are calculations from the published methods and figures shown, and depend on the data you enter. Coverage depends on the product, surface and application. Always follow the paint and wallcovering manufacturers’ data sheets and BS 6150 / BS 8000-12. Check prices and VAT with your own records and HMRC.