How to use this calculator
Enter your deck floor dimensions (length and width) in feet. If you also plan to stain railings and stairs, check those options and provide their measurements. The calculator computes total surface area for all selected components.
Next, choose your stain type. Transparent stains cover the most area per gallon but offer the least UV protection. Solid stains cover less area per gallon but provide the most durability and color. Semi-transparent and semi-solid fall in between. Select your application method as well, since sprayers use roughly 20% more product than brushes due to overspray.
The results show the total gallons of stain needed, broken down by component. You will also see a cost estimate if you enter a price per gallon, plus an estimated time for the project based on your application method. These figures help you buy the right amount without making extra trips to the store.
How stain type affects coverage and durability
Transparent stains let the full wood grain show through and cover 300 to 400 square feet per gallon. They look beautiful but offer minimal UV protection and typically need reapplication every one to two years. Semi-transparent stains add a tint of color while still showing the grain, covering 200 to 300 square feet per gallon with moderate durability of two to three years.
Semi-solid and solid stains provide the most protection and longest lifespan, often lasting three to five years. However, they cover less area per gallon (100 to 250 square feet) and hide more of the natural wood grain. Solid stains can also peel if not properly applied, so surface preparation is especially important. Choose the stain type that best matches your priorities for appearance, maintenance frequency, and budget.
Frequently asked questions
How much deck stain do I need for a 12x16 deck?
A 12x16 deck has 192 square feet of floor area. With a semi-transparent stain (roughly 250 sq ft per gallon) and two coats, you would need about 1.5 gallons. Add extra if you are also staining railings and stairs.
How many square feet does a gallon of deck stain cover?
Coverage varies by stain type. Transparent stains cover 300 to 400 square feet per gallon, semi-transparent stains cover 200 to 300, semi-solid stains cover 150 to 250, and solid stains cover 100 to 200 square feet per gallon. Weathered or porous wood will absorb more and reduce coverage.
Should I use a brush, roller, or sprayer to apply deck stain?
A brush or stain pad gives the most even penetration and uses the least product. Rollers work well for large flat areas but may not push stain into the wood grain as effectively. Sprayers are the fastest option but use roughly 20% more stain due to overspray, and you often still need to back brush for even coverage.
Do I need to strip old stain before restaining my deck?
It depends on the condition. If the old stain is peeling or flaking, you should strip it down to bare wood before applying new stain. If the old coat has simply faded and is still bonded to the wood, a light sanding and cleaning may be enough before applying a compatible stain over it.