Gate swing and slope clearance calculator
Find how far a swing gate can open on an uphill driveway before it scrapes, and how much ground clearance a full swing needs.
Scrapes at 33° — short of 90°
- Bottom gap needed for 90°
- 5½ in
- Widest it opens with 3 in
- 33°
- Leaf length
- 67½ in
- Each of two leaves · slope 4.6°
A single leaf on the same opening has 139 in leaves and needs 11 in of bottom gap to open 90°. A shorter leaf rises less, so splitting a gate into two leaves halves the gap a slope demands.
Ground rise under the leaf tip
| Opening angle | Ground rise at the tip | With your gap |
|---|---|---|
| 15° | 1½ in | Clears |
| 30° | 2¾ in | Clears |
| 45° | 3¾ in | Scrapes |
| 60° | 4¾ in | Scrapes |
| 75° | 5¼ in | Scrapes |
| 90° | 5½ in | Scrapes |
- The math assumes the driveway rises evenly in the direction the gate swings, and the ground along the closed gate is level. Measure the rise over the leaf’s length to get the grade.
- Fixes, cheapest first: swing the gate the other way (downhill, where the law and the site allow), split it into two leaves, raise the bottom rail, or use a slide gate — a slide gate moves along the fence line and never sweeps the slope.
- Automating it? UL 325 installation rules require a contact sensor on the bottom edge where a swing gate’s bottom is more than 4″ and less than 16″ above the ground anywhere in its arc.
Built to these numbers
How this calculator works
When a driveway rises in the direction a gate swings, the leaf tip meets higher ground the further it opens. At 90 degrees the tip is one leaf-length up the slope, so the gap a full swing needs is the leaf length times the grade.
With a smaller gap, the gate stops where the rise under its tip equals the gap. Halving the leaf length halves the rise, which is why a double gate or a slide gate is the usual answer on a steep driveway.