Quick answer
Fence stain (gallons) = length × height × 2 sides × coats ÷ coverage per gallon. A 100 ft fence 6 ft tall, stained on both sides with two coats at 250 ft² per gallon, needs 9.6 gallons for 1,200 ft².
Enter fence length, height, coats and coverage. The calculator returns the surface area and gallons.
Related tools: Fence Calculator: Posts, rails and pickets for a straight fence run. Deck Stain Calculator: Gallons of stain for a deck surface. Roof Pitch Calculator: Roof pitch as rise per 12 inches, angle, slope percent and rafter length factor.
How to use the Fence Stain Calculator
- Enter fence length (ft) (above 0).
- Enter fence height (ft) (above 0).
- Enter coats (a whole number, between 1 and 5). It starts at 2.
- Enter coverage per gallon (ft²) (above 0).
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Fence length | A number, in ft | > 0 |
| Fence height | A number, in ft | > 0 |
| Coats | A whole number | ≥ 1, ≤ 5, starts at 2 |
| Coverage per gallon | A number, in ft². Printed on the can | > 0 |
Formula and method
Formula
area = length × height × 2 sides; gallons = area × coats ÷ coverage
IEEE-754 double precision; shown to the decimals indicated.
Rough wood absorbs more than smooth wood; use the coverage printed on the can. Plan geometry only; confirm quantities with your supplier and local code before ordering.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Fence length = 100; Fence height = 6; Coats = 2; Coverage per gallon = 250.
| Result | Value |
|---|---|
| Stain needed | 9.6 gal |
| Surface area (both sides) | 1,200 ft² |
Example 2
Inputs: Fence length = 60; Fence height = 4; Coats = 1; Coverage per gallon = 300.
| Result | Value |
|---|---|
| Stain needed | 1.6 gal |
| Surface area (both sides) | 480 ft² |
The first line is the headline result (stain needed). Below it the fence Stain Calculator lists surface area (both sides), which describe the same case from other angles. IEEE-754 double precision; shown to the decimals indicated.
Both sides
The 1,200 ft² is 100 × 6 × 2 sides. If only one side is stained, halve the figure to 4.8 gallons. Picket gaps are not subtracted, so the estimate is slightly generous.
Absorption
Rough-sawn cedar or old fences can absorb more, lowering coverage to 150 ft² per gallon and raising the need to 16 gallons. Spraying wastes more product than brushing or rolling.
How the result changes with fence length
Holding every other input at the first worked example, this table changes only fence length. It shows how sensitive the answer is to that one value; each row was produced by running this calculator.
| Fence length | Stain needed | Surface area (both sides) |
|---|---|---|
| 50 | 4.8 gal | 600 ft² |
| 100 | 9.6 gal | 1,200 ft² |
| 200 | 19.2 gal | 2,400 ft² |
| 400 | 38.4 gal | 4,800 ft² |
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Fence length: entering "0" shows "Fence length must be greater than 0." beside that field and no result.
- Coverage per gallon: entering "0" shows "Coverage per gallon must be greater than 0." beside that field and no result.
Choosing between the Fence Stain Calculator and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [Fence Calculator](/construction/fence-calculator/) | fence length, post spacing and rails per section | Posts |
| [Deck Stain Calculator](/construction/deck-stain-calculator/) | deck length, deck width and coats | Stain needed |
| [Roof Pitch Calculator](/construction/roof-pitch-calculator/) | i know the and value | Pitch |
| [Tile Calculator](/construction/tile-calculator/) | area to tile, tile length and tile width | Tiles needed |
| [Aquarium Volume Calculator](/construction/aquarium-volume/) | length, width and water height | Capacity |
Background: construction estimates
Material quantities are geometry plus a margin. Calculate the exact volume or area, add an allowance for waste, spillage, cuts and uneven ground (calculator pages commonly mention 5 to 10 percent, a rule of thumb that varies by material and job) and round up to whole units. One cubic yard is exactly 27 cubic feet.
Suppliers often have minimum order sizes and may charge for small loads, so confirm quantities, product yields and local code with your supplier or a qualified estimator before ordering.
Assumptions and limitations
- Picket gaps are not deducted
Quantities are estimates. Add allowances for waste and site conditions, and follow local codes and a qualified professional's instructions for structural or safety-critical work.
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for fence length and coverage per gallon to confirm this.
Frequently asked questions
What coverage should I enter?
Use the label, usually 150 to 300 ft² per gallon.
Do I need two coats?
Many stains need one; check the label.
Does the post count?
Not separately; include them in the area if desired.
What does the Fence Stain Calculator calculate?
Gallons of stain for both sides of a fence. It returns Stain needed and Surface area (both sides).
What formula does the Fence Stain Calculator use?
area = length × height × 2 sides; gallons = area × coats ÷ coverage. Rough wood absorbs more than smooth wood; use the coverage printed on the can.
What do I need to enter in the fence Stain Calculator?
You enter Fence length (ft), Fence height (ft), Coats and Coverage per gallon (ft²).
How is the result rounded or limited?
IEEE-754 double precision; shown to the decimals indicated. Picket gaps are not deducted.
What is an example of a fence Stain result?
With fence length 100, fence height 6, coats 2 and coverage per gallon 250, the stain needed is 9.6 gal.
Can I rely on this calculator for a decision?
Quantities are estimates. Add allowances for waste and site conditions, and follow local codes and a qualified professional's instructions for structural or safety-critical work. For this calculator in particular: Picket gaps are not deducted.
Related calculators
- Fence Calculator — Posts, rails and pickets for a straight fence run.
- Deck Stain Calculator — Gallons of stain for a deck surface.
- Roof Pitch Calculator — Roof pitch as rise per 12 inches, angle, slope percent and rafter length factor.
- Tile Calculator — Number of tiles (and boxes) for an area.
- Aquarium Volume Calculator — Capacity and filled weight of a rectangular aquarium.
- Flooring Calculator — Flooring area with waste, and boxes if you know the coverage per box.
Sources
- OpenStax, Prealgebra 2e (Rice University): perimeter, area, volume, circumference and the Pythagorean theorem
- NIST Special Publication 811, Guide for the Use of the International System of Units (SI), Appendix B conversion factors (international foot 0.3048 m, inch 25.4 mm, US gallon 3.785411784 L)
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.