For a driveway gate from GateCrafters you would want one of two measurements: If you are planning on using our posts you would want the width from outside post placement to outside post placement. Then we can build a gate to fit within that space accounting for the posts, hinges and gate. So for example, if you have a fence that comes near the driveway on both sides and the gate posts are going to be next to the end post of the fencing then your measurement would be from fence end post to fence end post. If you have columns or posts that you want to mount our gates to then you would measure from inside face of post to inside face of post. We would design a gate and hinges to fit in that space. For the setback for the opener, this would only really come into play if using your own posts or columns or if you have a fence or wall perpendicular to the gate right where the posts are. Every opener is different. You would look at the setback of the chosen gate opener and make sure that you mount the gate with enough space to fit those measurements.