How Much Deck Stain Do I Need? Easy Coverage Calculator
Ordering too little stain means a second shipment and a mid-project delay; ordering way too much wastes money. Here is a simple way to estimate how many gallons of deck or fence stain you need.
Step 1: Measure the Square Footage
- Deck floor: length × width. A 12 × 16 ft deck is 192 sq. ft.
- Railings: a quick rule of thumb is about 2 sq. ft. of surface per linear foot of standard railing with balusters (more for decorative designs).
- Stairs: about 6–8 sq. ft. per step including treads, risers and stringers.
- Fences: length × height, then double it if you are staining both sides.
Step 2: Check the Coverage of Your Stain
Coverage depends on the product and especially on the wood. Penetrating deck stains typically cover roughly 150–300 sq. ft. per gallon per coat. Check the coverage listed on the product page, then adjust:
- Smooth, new or previously stained wood: use the high end of the range.
- Rough-sawn, weathered or very dry wood: plan on the low end; it soaks up much more stain.
- Two coats: many stains are applied in two coats, often wet-on-wet. The second coat usually takes less stain than the first.
Step 3: Do the Math
Gallons needed = total square feet ÷ coverage per gallon × number of coats. Round up, and add a little extra for touch-ups.
| Project | Approx. sq. ft. | Estimated gallons* |
|---|---|---|
| 12 × 16 ft deck, floor only | 192 | 1–2 |
| 16 × 20 ft deck with 40 ft of railing and 4 steps | about 430 | 2–4 |
| 100 ft privacy fence, 6 ft tall, both sides | 1,200 | 5–10 |
*Based on 150–300 sq. ft. per gallon. Always check your product's label coverage.
Save on Bigger Projects
If your estimate is 4 gallons or more, a 5-gallon pail is usually the better value. Many of our best sellers come in multi-packs and pails, including TWP 100 Series 5 Gallon, Sikkens Cetol SRD 5 Gallon and Ready Seal 5 Gallon. Ordering everything at once also keeps the color consistent across the project.
Don't Forget Prep
Most projects also need a deck cleaner and brightener and the right brushes or a pump sprayer. Browse all deck stains, and email Sales@TheStainDepot.com with your measurements if you'd like us to double-check your order. Orders placed before 4pm ET ship the same day.