Cantilever Gate Calculator
Sliding gate length, counterbalance, clear run, posts and footings.
A cantilever slide gate has no wheels on the ground — it hangs from rollers on two posts and is balanced by a tail that extends behind the opening. Enter the clear opening and the gate height to get the counterbalance, the overall frame length to order, how much straight, clear fence line you need beside the opening, and the roller posts and footings.
Calculation Results
Hoover Fence: counterbalance about 1/2 the opening, never under 4 ft. Planning a gate operator? The tail may need to be longer so the motor can pull the gate closed.
📱 More free Android calculators
Fencing, decking and drywall estimators from Dixon App Studio — all free on Google Play.
Smart Fencing CalculatorThis site
Fence posts, pickets, rails, concrete, gates and total project cost.
Get it on Google PlaySmart Decking Calculator
Deck boards, joists, footings, railings and material cost estimates.
Get it on Google PlaySmart Drywall Calculator
Drywall sheets, mud, tape, screws and finishing cost estimates.
Get it on Google PlaySod Calculator: Mulch, Topsoil
Sod pallets, mulch, topsoil and seed for the yard around your new fence.
Get it on Google PlayGravel & Stone Calculator
Gravel, crushed stone and base rock in tons and cubic yards.
Get it on Google Play🔧 Recommended Fencing Tools & Supplies
Disclosure: As an Amazon Associate I earn from qualifying purchases.
VEVOR Post Hole Digger,52cc 1450W Auger Digger,Gas Powered Earth Digger with Two Drill Bit 6''& 10''and 3 Extension Rods,for Farmland,Garden and Plant,EPA Certification,Black+Orange+White
$159.90
Check price on Amazon
H.B. Fuller Fast 2K Post Anchor Mix | Expanding Composite Footing Compound (Fence, 1)
$27.99
Check price on Amazon
Ready Seal Exterior Wood Stain | Semi-Transparent Oil-Based Formula | Professional Grade Stain and Sealer in One | Ideal for Decks, Fences, Pergolas, Wood Siding & More | Gallon | Dark Walnut
$39.99
Check price on AmazonPrices as of Oct 1, 2026, 4:36 AM UTC. Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.com at the time of purchase will apply to the purchase of this product.
🛠️ How This Calculator Works
The counterbalance (tail) is a fraction of the opening — about half is the usual standard — with a 4 ft minimum. The frame you order is the opening plus the tail. When the gate is open the whole frame sits beside the opening, so you need that much straight, level, clear run along the fence. The gate rides on four rollers on two posts; a third post catches the latch. Post size and footing come from the opening, for gates up to 6 ft high.
📐 Formula
Tail = max(opening × 0.5, 4 ft) · Gate length = opening + tail · Clear run = gate length · Footing volume = π × (dia ÷ 2)² × depth · Bags = ceil(3 footings ÷ 0.6 cu ft)📝 Example Calculation
A 12 ft driveway opening, 6 ft high chain link gate: Tail = 12 × 0.5 = 6 ft Gate frame = 12 + 6 = 18 ft Clear run beside the opening = 18 ft Roller posts: 4" O.D. (openings up to 20 ft) Footings: 3 × 18" dia × 42" ≈ 6.2 cu ft each → 18.6 cu ft ≈ 31 bags of 80 lb
💡 Pro Tips from Fence Builders
- Check the clear run first: if a wall, tree or slope sits within the gate length beside the opening, a cantilever gate will not fit — consider a swing or V-track gate.
- Keep the ground under the tail clear — the gate sweeps over it every time it opens.
- Set the two roller posts dead plumb and in line; most binding comes from posts that lean or twist.
- Leave the concrete to cure before hanging the gate; the roller posts carry the whole weight on one side.
- If you will automate it, buy the operator first and follow its maker's tail length and mounting spec.
❓ Frequently Asked Questions
How long should a cantilever gate counterbalance be?
About half the gate opening, per Hoover Fence's cantilever slide gate guide, and never less than 4 ft. Some makers build 40% to 50% tails; a longer tail makes a stiffer gate. A 12 ft opening needs a 6 ft tail and an 18 ft gate frame.
How much room do I need for a sliding gate?
A straight, clear run beside the opening at least as long as the whole gate frame — opening plus counterbalance. For a 12 ft opening with a 6 ft tail that is 18 ft of fence line with nothing in the way.
What size posts does a cantilever gate need?
For gates up to 6 ft high, Hoover Fence lists 3 in O.D. roller posts for openings up to 10 ft, 4 in up to 20 ft and 6-5/8 in up to 32 ft. Taller or longer gates need bigger posts — use the gate maker's table.
How deep should cantilever gate posts be set?
Hoover Fence recommends footings 18 in diameter by 42 in deep for 3 to 4 in posts and 24 in by 42 in for 6-5/8 in posts. Your frost depth or local code may require deeper.
How many rollers does a cantilever gate use?
Normally four — two at the top and two at the bottom — mounted on the two roller posts. The frame's top and bottom tracks run through them.
Is a cantilever gate better than a rolling gate?
A cantilever gate has no wheels on the ground, so it works on gravel, snow and uneven driveways and has no track to clog. It needs extra clear run for the tail; a V-track rolling gate needs less room but a smooth, clean track.
📬 Free Fencing Cost Guide
Get weekly fencing tips, material cost updates, and exclusive calculator guides — straight to your inbox.
No spam, ever. Unsubscribe anytime.
📝 Related Articles
🧮 You May Also Need
Related calculators for your fencing project
Cantilever gate sizes by opening
At a 50% counterbalance with the 4 ft minimum, gates up to 6 ft high.
| Opening | Tail | Gate frame | Roller posts |
|---|---|---|---|
| 6 ft | 4 ft | 10 ft | 3" O.D. |
| 10 ft | 5 ft | 15 ft | 3" O.D. |
| 12 ft | 6 ft | 18 ft | 4" O.D. |
| 16 ft | 8 ft | 24 ft | 4" O.D. |
| 20 ft | 10 ft | 30 ft | 4" O.D. |
| 24 ft | 12 ft | 36 ft | 6-5/8" O.D. |
| 30 ft | 15 ft | 45 ft | 6-5/8" O.D. |
Cantilever vs other sliding gates
A cantilever gate hangs from rollers and never touches the driveway, which is why it suits gravel, slopes across the opening and snowy climates. A V-track gate rolls on wheels in a ground track and needs less run beside the opening, but the track has to stay clean and level. Swing gates need no run at all but need a clear arc to open into.
Source: Hoover Fence Co., Cantilever Slide Gate System Overview (counterbalance, rollers, post sizes and footers).
Related calculators
Plan a swing gate with the gate calculator, count the rest of the fence with the chain link calculator and its parts list, and size post concrete with the fence post concrete calculator.