Fence Stain Calculator

Work out how much stain to buy for your fence. Account for both sides, openings, rails and posts, and the coverage printed on your stain container.

Measurement systemSwitching units converts the values already entered.

Fence sides to stain

Fence lengthftTotal fence run, including any openings you will subtract.

Average fence heightftFor varying heights, use an area-weighted estimate or calculate sections separately.

Area not being stained, per sideft²Subtract gaps or openings only. Do not subtract gates if you will stain them.

Extra surfaces, all sides combinedft²Add exposed board edges, rails, posts and caps not counted in the flat fence faces. Enter their total area once.

Coats required by your productFollow the product label; two coats is not a universal requirement.

First-coat coverageft²/US galExample: 250–300 ft²/US gal for BEHR DECKplus semi-transparent. Default uses the lower end.

Second-coat coverageft²/US galExample: 500–600 ft²/US gal for the same product. Enter your own label value.

Extra material allowance%Added material for uncertainty and application losses; this is a planning input, not a manufacturer requirement.

Container sizeUS galAll containers are assumed to be this same size. Whole containers are rounded up.

Price per container (optional)your currencyUse your local purchase price. Zero means no cost estimate.

Calculation results

Estimated material

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How to use this calculator

Measure the fence faces

Enter the length and height, choose one or both sides, and subtract any uncoated openings per side.

Include the extra wood

Measure exposed rails, posts, board edges and caps separately. Add their combined area once; face area alone can undercount a slatted or shadowbox fence.

Read the stain label

Set each coat’s coverage and the required number of coats. A second coat may cover more area per gallon than the first.

Choose the package you will buy

Enter an allowance and container size. Compare the liquid estimate with the rounded purchase quantity. A test patch gives a better coverage estimate for your wood.

Formula and worked example

Stain area = (length × height − excluded area per side) × sides + extra area
Base stain = area ÷ first-coat coverage + area ÷ second-coat coverage (when selected)
Order estimate = base stain × (1 + allowance ÷ 100)
Containers = round up(order estimate ÷ container size)

A 100 ft × 6 ft fence stained on both sides has 1,200 ft² of flat face area. With no openings or extra area, coverage of 250 ft²/gal for coat one and 500 ft²/gal for coat two requires 4.8 + 2.4 = 7.2 US gal. A 10% allowance makes 7.92 US gal, so buy eight 1-gallon containers. At a user-entered price of 40 per container, the material estimate is 320 in that currency.

Example stain quantities for a 6-foot fence

Illustrative two-coat calculation at 250 and 500 ft²/US gal; no openings or extra surfaces. These are not universal coverage rates.
Fence length	Both-side area	Liquid with 10% allowance	1-US-gal containers
50 ft	600 ft²	3.96 US gal	4
100 ft	1,200 ft²	7.92 US gal	8
150 ft	1,800 ft²	11.88 US gal	12

Frequently asked questions

How much stain do I need for both sides of a fence?

Multiply length by height for one face, subtract uncoated openings per side, then multiply by two. Add extra surfaces once. Divide the resulting area by each coat’s coverage and add the amounts.

Should I multiply the first-coat amount by two?

Only if both coats have the same coverage rate. This calculator accepts a separate second-coat rate so a more absorbent first coat is not treated as identical to the second.

Does this work for picket or shadowbox fences?

Use measured wood surface area, not just the outline. Subtract open gaps and add exposed edges and extra faces. Overlapping shadowbox boards can have substantially more stainable surface than length × height.

Are the defaults a product recommendation?

No. They are a worked example based on the cited BEHR product’s lower coverage values. Check your chosen product and test a small area; roughness, porosity, preparation and application affect consumption.

Does the estimate include labor, cleaner or tax?

No. Optional cost covers only the rounded number of stain containers at your entered price. Labor, preparation products, equipment and tax are excluded.

Methodology and sources

This is a material estimate, not a guaranteed purchase quantity or application specification. Defaults are editable. Do not apply extra coats or thicker coats just because material remains. Uneven, slatted and overlapping fences need actual surface measurements. Gallons here are US liquid gallons, not Imperial gallons.

BEHR DECKplus semi-transparent stain — Source for the example first- and second-coat coverage rates and two-coat requirement.
NIST Handbook 44 — measurement tables — Unit conventions: US liquid gallons, international feet and metric units.

Sources checked September 1, 2026. Referenced organizations do not endorse Efficienco. Calculations retain full precision until display; purchase units round up.