Finishing
Polyurethane / Varnish Coverage Calculator
Calculate how much poly, varnish, or hardwax oil you need — by surface area, coats, and product type.
Calculator
Oil-based poly / Water-based / Hardwax oil
Yes / No
What makes this different
Standard coverage charts assume one coat of oil-based poly. This one differentiates oil-based, water-based, and hardwax oil, lets you add a sanding sealer step, and shows you how much extra surface area each additional coat costs.
Who it's for & when to use it
Finishing a tabletop, hardwood floor, or kitchen cabinet set.
How to use
- Enter the dimensions of your material or the parameters of your project.
- Adjust the optional knobs (waste factor, kerf, planer allowance) to match your shop practice.
- Click Calculate and read the output. Use the per-item breakdown for ordering, the totals for budgeting.
- Compare the result to your lumber yard's quote — the effective $/BF column is the apples-to-apples number.
Formula: Coverage: oil-based ≈ 125 sq ft/qt, water-based ≈ 125 sq ft/qt, hardwax oil ≈ 200 sq ft/qt (covers more but goes on thinner).
Notes & tips from the shop
- Sand between coats with 220–320 grit. Skipping this is the #1 reason for a hazy finish.
- Thinner coats are better than thick ones — they level out, dry harder, and don't trap bubbles.
- Hardwax oil is forgiving and repairable; poly is more durable but harder to spot-repair.
Frequently asked questions
Can I roll poly or only brush?
Both work. Use a foam roller for water-based to avoid brush marks; use a natural-bristle brush for oil-based.
How long before light use?
Poly is dry-to-touch in 2–4 h but doesn't fully cure for 2–4 weeks. Don't set hot mugs on it for a month.
Why does my finish look cloudy?
Moisture trapped under the film, or a coat applied before the previous one cured. Sand back and recoat.
Limitations
Spray application uses 20–30 % more material for transfer loss; toggle 'waste' accordingly.
All calculations happen in your browser — nothing you type is sent to a server.