Deck Stain Calculator
Measure deck floors, stair surfaces and square balusters, then calculate finish gallons and whole containers.
Choose the worksheet for your task
- Quick estimateOne rectangle plus extra area you have already measured.
- Measure the deck by componentAdd floor, tread, riser and square-baluster surfaces without multiplying coats twice.
These are independent worksheets. Inputs do not transfer between them. Use the download button beside the result you want to keep.
- Surface area
- 192 sq ft
- Liquid required
- 1.056 US gal
- Purchased volume
- 2 US gal
- Purchased surplus
- 0.944 US gal
- Material subtotal (entered price only)
- Not supplied
Whole packages round up. Prices include only the items you enter. Delivery, tax and installation may be extra.
Build a deck surface ledger
Floor area alone misses steps and rail components. This independent worksheet adds measured tread tops, riser faces and square balusters to the net floor area. Only include surfaces you intend and are permitted to coat.
Optional stair, baluster and other areas start at zero. Add only the surfaces in your project; the worked example below is separate. Floor and product values are editable examples and still need review.
See which stair surfaces to measure
Surface ledger for one finish
| Surface | Area (sq ft) |
|---|---|
| Deck top face | 192 |
| Stair tread tops | 0 |
| Stair riser faces | 0 |
| Square baluster long faces | 0 |
| Other measured surfaces | 0 |
| Total measured surface | 192 |
At your entered first- and later-coat rates, including 10% allowance: 1.2672 US gal. Buy 2 containers of 1 US gal, totaling 2 gallons (0.7328 gallons modeled surplus).
Material subtotal: Price not supplied. Tax, delivery, cleaning, repairs, application equipment and labor are excluded.
Use this combined order only when the same finish and coverage assumptions apply to all included surfaces. Different products, colors or substantially different absorption conditions need separate calculations. Follow the product’s permitted substrates and coat instructions.
Worked example: the floor is only one line
A 16 × 12 ft top face contributes 192 sq ft. Four treads at 4 ft wide and 12 in deep add 16 sq ft. Four risers at 4 ft wide and 7 in high add 9.3333 sq ft. Twenty square balusters, each 3 ft exposed height and 1.5 in side width, with four exposed long faces, add 30 sq ft. A separately measured 24 sq ft for other components gives 271.3333 sq ft total.
Using illustrative first- and second-coat rates of 250 and 500 sq ft per US gallon plus 10% allowance gives 271.3333 × (1/250 + 1/500) × 1.10 = 1.7908 gallons, or two 1-gallon containers. The floor alone under those same assumptions needs 1.2672 gallons; both happen to round to two containers, but their modeled surplus differs.
If the stair has no riser faces, set risers to zero: total area becomes 262 sq ft and liquid demand is 1.7292 gallons. Do not multiply the physical surfaces by the number of coats before entering them; the product calculation already applies coats.
Check label coverage and purchase assumptions · Record preparation and costs outside the material subtotal
How to calculate
Length and width cover the deck surface. Enter railings, stair treads and other measured surfaces as extra area; they are not automatically included.
Worked example
Length (ft): 16 · Width (ft): 12 · Faces / sides: 1 · Extra surface area (sq ft): 0 · Coats: 1 · First-coat coverage (sq ft / US gal): 200 · Container size (US gal): 1 · Extra material (%): 10.
These inputs produce 2 containers to order. Change the measurements above to match your project.
Measure the right surfaces
Measure the walking surface separately from stair treads, fascia and rails. Keep faces at one when only the tops of the deck boards are included. Add separately measured surfaces to Extra area and use coverage for your actual finish and wood condition.
A second example you can check
A 16 × 12 ft deck is 192 sq ft. Adding 48 sq ft of measured steps and rails gives 240 sq ft. At 200 sq ft/gal, one coat and 10% extra need 1.32 gallons, so two 1 gallon containers are required. Two coats at that same per-coat rate would require 2.64 gallons.
Where estimates go wrong
A deck footprint omits vertical and narrow surfaces, while treating a railing as a solid rectangle can overstate its actual wood area. Weathered, rough or previously coated wood may not match a label’s most generous coverage figure. A test patch can reveal that difference.
Build your supplier order
Read the finish label for deck suitability, preparation, moisture conditions, recoat timing and application rate. The quantity tool does not determine whether old coatings should be removed or whether a particular finish will adhere.
Deck Stain: practical questions
Do I set faces to two for two coats?
No. Faces multiply physical surface area; coats multiply applications. Use the Coats field for a second application.
Are railings automatically included?
Not in the quick estimate. The component ledger can calculate identical square baluster faces from dimensions; measure rails, posts and other exposed surfaces separately and add them once.
Inputs and references
BEHR DECKplus semi-transparent stain — One product example has different first- and second-coat coverage rates. Enter each label rate separately; these rates do not apply to every finish.
YardTakeoff · Revised October 21, 2026 · Formula checks and scope · Report a calculation error