Building a fence on a hill might be as simple as building a fence on level ground, because rail and wire fences can often simply follow the contours of the hill. However, panel and woven wire fences cannot do this without looking sloppy and uneven, and consequently these fences must be "stepped" up or down the slope in stages to preserve a uniform, even appearance. Sometimes it is even desirable to step a rail or wire fence, even if it is not necessary, strictly speaking.
Hammer one stake into the ground at the top of the hill and another at the foot of the hill.
Tie a loop of twine around the stake at the top of the hill, and push the twine down to ground level. Walk down to the bottom of the hill, unrolling the spool of twine as you go. Tie the other end of the twine in a loop around the stake at the bottom of the hill, ensuring the twine is taut. Set a carpenter's level onto the twine and adjust it up or down along the lower stake until the twine is in a level, horizontally straight position.
Measure the space between the twine and the ground at the lower stake. This yields the elevation of the hill slope from its foot to the top.
Determine the distance between fence posts. For a panel fence or a split rail fence, this is the width of the panels or the split rails. For a woven wire fence, that depends on the weight of the wire and could be anywhere from eight to 16 feet.
Walk up or down the hill slope between the stakes with a measuring wheel to determine how long the slope is. Determine how many fence posts are needed to cover the hill slope by dividing this distance by the spacing between the posts from Step 4.
Divide the elevation of the slope (from Step 3) by the number of fence posts. This yields the distance each successive panel, rail or section of fence should "step" up as it ascends the hill.
Build the fence following the specific instructions for that type of fence, with one exception. Every panel, section of chain-link or wire or set of rails must be raised above the section of fencing behind it by the "stepping" measurement from Step 8. If you are building a privacy fence with a 2-inch "step," every panel must be installed 2 inches higher than the one before it as the fence stretches up the hill.
For a steep or long slope, taking an accurate elevation measurement will require either the use of a longer stake at the bottom of the hill, or taking the measurement in more manageable stages.