Bare timber drinks stain, and rough sawn drinks far more than planed — the same tin can cover half the area on a sawn fence that it covers on a smooth deck. This works in tins, and tells you when the second coat needs less than the first.
Decking, fencing, sheds and garden timber. Enter the area, pick the finish, and tell us the tin sizes your shop stocks.
Works in metric and US imperial — you choose at the start and can switch at any time. Every figure this calculator uses is published with its source, and the result comes with a printable order sheet. No account, no email, and nothing you type leaves your browser.
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The same tin can cover half the area on a sawn fence that it covers on a smooth deck. That is not a small variation to allow for with a percentage — it is the main variable on the whole job. Tell the calculator which finish you are working on and it works in tins your shop actually stocks, rather than handing you a litre figure nobody sells.
On a fence: both sides if you are doing both, plus the posts and the gravel boards, which together are a surprising fraction of the total. On a deck: the board faces are the easy part, but the fascia, the steps, the risers and the visible sides of the joists all take stain and are routinely left out of the sum. Measuring these in is the difference between finishing the job and stopping halfway through the second coat.
End grain drinks the most and it is where rot starts, so every cut end wants a generous soak before assembly if you can manage it — this is the single highest-value place to put stain on any outdoor timber. Stir, do not shake, and never thin it: pigment settles and needs stirring back through the tin, shaking makes bubbles that show in the finish, and thinning changes both colour and durability. Do not stain in direct sun or with rain forecast within a few hours — sun makes it dry before it penetrates, rain washes it off. Overcast and dry is ideal.
It depends heavily on whether the timber is rough sawn or planed — the same tin can cover half as much area on sawn timber. Measure both sides if you are doing both, and include the posts and gravel boards, which are a surprising fraction of the total.
Because the surface area is far greater than it looks and bare open grain absorbs rather than coats. A smooth planed deck takes a fraction of what the same area of sawn fencing does.
Yes, generously, and ideally before assembly. End grain absorbs the most and it is where rot starts — it is the highest-value place to put stain on any outdoor timber.
No. Thinning changes both the colour and the durability. Stir it thoroughly rather than shaking, since shaking creates bubbles that show in the finish, and pigment that has settled needs stirring back through the whole tin.