Free wood stain calculator. Enter area to find the stain you need for one coat and for two coats, at a planning coverage of 10 m2 per litre.
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Enter the area in square metres. This calculator uses a planning coverage rate of 10 square metres per litre, so one coat needs area divided by 10 litres, and two coats needs twice that. For 20 square metres that gives 2.0 litres for one coat and 4.0 litres for two coats. Rough or weathered wood needs more than the planning rate, so check your tin and the coverage sections below before buying.
Stain litres equal area times coats divided by coverage rate. This calculator uses 10 square metres per litre as its planning rate, so one coat for 20 square metres is 20 divided by 10, which is 2.0 litres, and two coats is 4.0 litres. For 25 square metres the same maths gives 2.5 litres for one coat and 5.0 litres for two coats. Always replace the planning rate with your tin coverage rate when you know it, since that rate is the one that decides the real purchase.
Deck stain coverage per gallon in competitor guides is usually 150 to 300 square feet per gallon for the first coat, depending on wood age, condition and porosity. A gallon is 3.785 litres and 150 square feet is about 14 square metres, so that range is roughly 3.7 to 7.4 square metres per litre on a first coat. Second coats go farther, often 200 to 300 square feet per gallon, because the wood pores are already partly filled. This calculator planning rate of 10 square metres per litre suits smooth, sealed wood better than a rough deck, so rough decks should plan on more stain.
Measure the deck area as floor length times width, then add railings and stairs. Railing area is railing length times railing height, with 3 feet as a common railing height. Stair area is steps times step width times run plus rise for each step. For a fence, measure one side and double it if you stain both sides. Add every section before you run the calculator, since missing railings and stairs is the most common measuring mistake.
Wood type and surface condition change coverage more than stain colour does. Smooth hardwood absorbs least, pine and cedar absorb a medium amount, and rough or weathered wood absorbs the most, with weathered decks using 20 to 40 percent more stain than smooth decks. Bare, unprimed wood also drinks stain, while previously sealed wood needs less. If your wood is rough, weathered or porous, buy above the calculator result rather than exactly at it.
Penetrating stain soaks into open grain, so its coverage varies widely with porosity. Gel stain sits on the surface instead, giving even colour on blotch prone woods but typically covering 30 to 40 percent less area per gallon than a penetrating stain. Do not use a penetrating stain rate for a gel stain job: check the gel product label rate instead. Oil based and water based penetrating stains also differ, so the tin rate still rules.
A waste buffer covers end grain, rough spots, spray loss and measuring error. A 10 percent buffer suits smooth projects, while 15 to 20 percent suits rough, porous or outdoor wood. Buy a spare tin from the same batch for touch ups, since stain colour can vary slightly between production batches and a later batch may not match. Keep leftover stain sealed, labelled and stored for repairs.
One coat suits new wood under one year old for transparent and semi transparent stains, since dense new wood will not absorb a second coat well. Two coats suit weathered wood and richer colour, applied with drying time between coats of at least 2 to 4 hours, or the time your tin lists. Apply the second coat at right angles to the first for even coverage. Calculate a topcoat such as polyurethane as a separate calculation, since it has its own coverage rate and coat count, and never add it to the stain litres.
Multiply area by coats and divide by coverage rate, then add a waste buffer. This calculator uses 10 square metres per litre as its planning rate.
Usually 150 to 300 square feet per gallon for a first coat on a deck, with second coats covering more because the wood is already partly sealed.
Yes. A 10 percent buffer suits smooth wood, while 15 to 20 percent suits rough, porous or outdoor wood. Keep a spare tin from the same batch for touch ups.
Yes. Porous softwoods and weathered surfaces absorb far more stain than dense or already sealed wood, so they need a larger purchase.
No. Gel stain sits on the surface and covers 30 to 40 percent less area per gallon than penetrating stain, so use the gel label rate.
One coat for new wood under one year old, and two coats for weathered wood or deeper colour, with drying time between coats.
At least 2 to 4 hours for most stains, or the time your tin lists. Avoid heavy use for 1 to 2 days after the final coat.
Yes, with the same area times coats divided by coverage formula, but run it separately, since topcoat rates and coats differ from stain.