Wood Finish Coverage Calculator
Estimate how much finish to buy so you avoid a mid-project run to the store or a shelf of leftover cans. Enter the surface area in square feet, the number of coats, and the finish type, and the tool returns the total coated area, the gallons required, and the same amount in quarts. It uses mid-range coverage figures for stain, paint, polyurethane, and Danish oil, and runs entirely in your browser.
How to calculate finish coverage
- Measure the surface area you plan to finish and enter it in the Surface area field, in square feet.
- Set the number of coats in the Coats field, using at least 1.
- Pick the product from the Finish type list: Polyurethane, Stain, Paint, or Danish oil.
- Read the Coated area, Gallons, and Quarts result tiles.
- Round up to the can sizes sold and keep a little spare, then use Copy estimate to save the figures.
Examples
120 sq ft, 2 coats of polyurethane
Area 120 sq ft, 2 coats, polyurethane (400 sq ft/gal)
240 sq ft coated, 0.6 gallons (2.4 quarts)
300 sq ft, 2 coats of stain
Area 300 sq ft, 2 coats, stain (200 sq ft/gal)
600 sq ft coated, 3 gallons (12 quarts)
90 sq ft, 3 coats of Danish oil
Area 90 sq ft, 3 coats, Danish oil (150 sq ft/gal)
270 sq ft coated, 1.8 gallons (7.2 quarts)
Frequently asked questions
How much stain do I need?
Multiply the surface area by the number of coats, then divide by the coverage per gallon. For 300 square feet at two coats of stain rated 200 square feet per gallon, that is 600 divided by 200, which is 3 gallons.
How many square feet does a gallon cover?
It depends on the finish. This tool uses about 200 for stain, 350 for paint, 400 for polyurethane, and 150 for Danish oil, all in square feet per gallon for a single coat. Your can may list a different figure, so trust the label when it differs.
Why does coverage drop on bare or porous wood?
Unsealed and open-grain woods soak up the first coat, so real coverage on that coat is often lower than the can figure. Buy a little extra, and expect later coats over a sealed surface to stretch further.
Should I round up when buying?
Yes. Finish is sold in fixed sizes such as quarts and gallons, so round the result up to the next size. An estimate of 0.6 gallons means a single gallon, which also leaves spare for touch ups.
Does the estimate include the back, edges and end grain?
Only if you include them in the surface area. For boards finished on both faces, count both sides plus the edges when you measure, since thirsty end grain in particular can pull in extra finish.
What if my product lists a coverage figure not in the list?
The on-page tool uses a fixed figure per finish type. If your label differs, scale the gallons by hand, or use the API where a coveragePerGallonSqFt value overrides the built-in numbers.
How is the coated area figure calculated?
It is simply the surface area multiplied by the number of coats. Two coats over 120 square feet is 240 square feet of coating work, which is what the gallons figure is based on.
Is any of my project data uploaded?
No. Every calculation happens locally in your browser, so nothing you enter is stored or sent to a server. You can try different coats and finishes freely.
What related tools help plan a woodworking project?
Use the board feet calculator to price lumber, the cutting list calculator to plan parts from your boards, and the shelf sag calculator to check that a span will hold its load.
Learn more
- Estimating Stain and Finish for a Project
Measure surface area correctly, choose coats by finish type, and buy the right amount of stain or polyurethane without waste.
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