How to use this calculator
Start by selecting the finish type you plan to use. The calculator includes common options from oil-based polyurethane to Danish oil to shellac, each with its published coverage rate and recommended number of coats.
Enter your surface area using either the dimension helper (enter length, width, quantity, and whether you are finishing one or both sides of each piece) or switch to the direct square footage input if you already know the total. For projects with significant exposed end grain (like a cutting board or butcher block table), check the end grain box to add 25% to the estimate.
The results show how much finish to buy in quarts or gallons, the amount needed per coat, and a coat-by-coat schedule with recoat and cure times. Enter a price per quart to see a cost estimate.
Choosing the right finish
Oil-based polyurethane is the most durable option for furniture that sees daily use (dining tables, desks, kitchen cabinets). It builds a hard film that resists water, scratches, and heat, but it takes longer to dry and has a noticeable odor during application.
Water-based polyurethane dries faster, has less odor, and does not yellow over time. It is a good choice for light colored woods where you want to preserve the natural tone. However, it raises the grain more on the first coat and requires more sanding between coats.
Oil finishes (Danish oil, tung oil, boiled linseed oil) soak into the wood rather than forming a film on top. They give a natural, close-to-the-wood feel that many woodworkers prefer. The trade-off is less protection against water and scratches, and they need periodic reapplication on high-use surfaces.
Frequently asked questions
How much polyurethane do I need?
Oil-based poly covers about 450 sq ft per gallon per coat. For a dining table finished on both sides with three coats, one quart is usually enough. Water-based covers about 550 sq ft per gallon.
How many coats should I apply?
Three coats is standard for most furniture. High-wear surfaces like tables and counters benefit from four. Decorative items can get away with two. Sand lightly between each coat with 220 grit.
How long between coats?
Oil-based poly: 4 hours. Water-based poly: 2 hours. Danish oil: 4 to 6 hours. Pure tung oil: 24 hours. Shellac: 1 hour. These assume 70°F and moderate humidity.
Does end grain absorb more finish?
Yes, end grain can absorb two to three times more finish than face grain. If your project has significant end grain exposure (cutting boards, butcher blocks), check the end grain option to adjust the estimate upward.