What hinge should I use?

To know how heavy a hinge you should put on a gate, it helps to know a few things. You need to know how much the gate weighs, and how long it is, and how high it is. The height measurement should be the distance between the hinges, and the length will be divided in half to give you the approximate center of gravity. (We don't have to be precision engineers here, within a few inches should be close enough.)

Once you know these things, finding out how big a load that gate will put on the hinge and post is easy to find. Multiply the gate weight in pounds by ½ gate length in feet. Divide that result by the height of the gate in feet. The answer you get will be the load, in pounds that the gate puts on the hinge and post.

Modern Fence Technologies has published a series of charts that show the load ratings of the T-rods manufactured for MFT hinges. The T-rod is typically the point of failure for a hinge that is overloaded, so if you match the T-rod to the load, your hinge will be properly sized to support your gate.

To see this formula in action, view this video. In it you see a demonstration of this formula modified to reflect added load on the gate, and the comments section explains the math. For a gate only, with no extra load, use the following formula: Gate Weight X ½ Gate Length/Gate Height. Remember, gate height is actually the distance between the hinges.

For more about this see: Choosing the Right Hinge