Construction & DIY · Woodworking
Wood finish quantity calculator.
List the pieces you are finishing, enter the coverage from the product label and the number of coats to get the volume to buy.
Inputs
Finish to buy
Enter at least one piece and the label coverage.
How much finish do I need for a woodworking project?
The volume is the surface area times the number of coats, divided by the product's coverage, plus an allowance. Coverage is printed on the container as an area per volume, so this tool takes it from the label rather than guessing: coverage differs between stain, oil, shellac and polyurethane, and between sanded and open-grain wood. Area counts only the faces you tell it to include, so add edges as extra pieces if they matter.
Worked example. Two tops of 48 by 24 in, both faces, is 48 × 24 × 2 × 2 = 4,608 sq in = 32 sq ft. Two coats of a finish that covers 400 sq ft per US gallon with a 10% allowance is 32 × 2 / 400 × 1.10 = 0.176 US gallon, about 0.67 L or 0.7 US quart.
Unit conversions use the exact definitions (1 US gallon = 3.785411784 L, 1 sq ft = 0.09290304 m²) listed in NIST SP 811. Always follow the label for the number of coats, drying times, ventilation and protective equipment.
Frequently asked questions
How much polyurethane do I need for a table top?
Find the area of the surface, multiply by the number of coats, and divide by the coverage on the can. A 48 by 24 in top finished on one face with two coats of a finish covering 400 sq ft per US gallon needs about 0.04 US gallon before the allowance.
Where do I find the coverage number?
On the product label or data sheet, usually in square feet per US gallon or square metres per litre. It differs between finishes, so use your product's figure.
Should I allow extra for waste?
Yes; absorption into bare wood, end grain, rags and brushes use more than the flat-area figure. The default 10% is a starting allowance you can change, not a published figure.
Does this include the edges and legs?
Only what you list. Add edges, legs and aprons as separate pieces with the faces you plan to finish.
Sources
Checked
NIST SP 811 Appendix B.8 gives the conversion factors for the US gallon and the square foot. Product coverage and the waste allowance are inputs you control, not published figures. Runs entirely in your browser. Nothing you type is sent or stored.
Scope
Quantity estimate for planning a purchase. Follow the product label for application, ventilation, protective equipment and safe disposal of used rags.