Gates come in a lot of different sizes so this is a quick review of what size would be appropriate for what application:
4′ gate or door: A width appropriate for one horse pass through such as a stall or single horse paddock. Standard size for a stall door; fits a wheelbarrow. Easy for a human to close and generally does not sag.
Minuses: if you have a touchy horse who doesn’t like narrow pass-throughs or another horse who is trying to barge by the first horse it can be problematic.
My thoughts – Personally, my favorite gate size and one I use when I want to get only one horse out – as a second horse will be forced behind the first due to the lack of width, and you can close the gate on the nosy second horse.
6′ gate: a nice compromise when you need a bigger gate then a 4′. Still too narrow for two horses to pass through at the same time. The size of the gate still allows easy opening by one person.
Would fit a few narrow ATV’s, golf carts and riding lawn mowers, however, if any of these had a side attachment or were the larger versions go with an 8′ gate to be sure.
My thoughts – Personally, I would go up to 8′ to allow even easier access of small equipment machines as 6′ may still be narrow especially if you have a turn, horses who are energetic when released to field, or have equipment that will be pulling something behind (i.e. ATV with manure spreader) or has side attachments.
8′ gate: in a pinch, can be a nice size for animals to pass in and out, side by side, if friendly. Would fit a riding lawn mower, ATV and/or golf cart so a good choice if the paddock was going to be mowed, fertilized and maintained only by these smaller vehicles.
My thoughts – best for entry into small paddocks where only smaller equipment will be used for maintenance as it is not wide enough for trucks, tractors etc…
10′ gate: Generally, I would increase and go to a 12′ gate for more versatility. Would be possible for smaller trucks or larger trucks if the entrance is straight.
12′ gate: Minimum needed for access of vehicles such as 3/4 ton trucks, standard trailers, small tractors, etc… However, if a sharp turn is required, no matter how large the gate, the vehicle won’t be able to maneuver. Make sure that the drive to and from the gate is straight and doesn’t have overhanging tree branches.
A good size if multiple horses are passing through the gate at the same size.
My thoughts – most common gate size seen for tractors to access pastures for mowing and fertilizing. As long as there is a straight entrance, most vehicles will be able to travel through without issue. Could be made with two 6′ gates. Will need a wheel or some sort of anti-sag support on the free swinging gate end.
14′ gate: Would allow a bit more tractor room for entering, especially if there is a sharp corner though I would go with the bigger 16′ gate if this is needed due to a curve or bend in the road.
16′ gate: Would allow the largest trailers/trucks – such as hay trailers, gravel dump trucks, large horse rigs, to enter as long as there are no sharp turns and bends are long and gradual.
A 16′ gate opening can be two 8′ gates, each with a supporting wheel to prevent sag.
My thoughts – The main entrance to your property should have the largest gate you can install with a straight or large curve in the road to areas such as hay storage, bedding storage, unloading horses from big rigs, and, if you need too, re-supply the footing in arenas.
The bigger your establishment – the more horses you are caring and buying for – the larger the gates needed. This is because large quantity hay and bedding deliveries often come on huge flatbed trucks. Even small establishments may get a large semi during delivery if they are doing multiple delivers on the same day or if you are building a house or barn, delivery trucks will also be semi-s.
Remember – plan at least one drive, usually the main entrance though sometimes it’s a side, auxiliary entrance straight to the barn, to be wide and as straight as possible (minimum 12′ wide road).