Deer are capable jumpers, and a fence height that comfortably contains a dog or marks a property line does very little to keep deer out of a garden or orchard. Getting height right is the single most important decision in a deer exclusion fence.
Why standard heights fail
A typical 4 to 6 foot residential fence, more than enough for most other purposes, is well within a deer’s jumping range under normal conditions. Exclusion fencing for deer commonly needs to run considerably taller, often cited in the 7 to 8 foot range, to reliably discourage jumping.
Slope works against you
A fence on a slope is effectively shorter from the uphill side, since the animal starts its jump from higher ground relative to the fence line. If your garden or orchard sits on any kind of grade, consider the effective height from the highest adjacent ground, not just the fence’s own height measured vertically.
Material is a cost and practicality decision, not a height decision
Reaching 7 to 8 feet in solid wood is expensive and visually heavy for most residential settings. Chain link, or a purpose-built deer netting system, commonly reaches the needed height at a lower material cost and less visual impact than a solid wood fence of the same height.
Do not forget the bottom of the fence
Height solves the jumping problem, not a gap at ground level a deer (or a smaller animal) can go under, particularly on uneven ground. Check that the bottom of the fence follows the actual grade closely along the whole run.
Plan the material list
The deer fence calculator defaults to chain link at an exclusion-appropriate height and computes posts and concrete for your run. If your site has any real slope, the fence slope calculator gives you the true, slope-adjusted length to plan material against.
Related reading: how to calculate fence materials for a sloped yard, how far apart should fence posts be.