A fence is only as good as its posts. Set them right and you won’t be fixing a leaning line in a few years.

Quick answer Call 811 first. Dig a hole about three times the post’s width (12 inches for a 4-inch post) and about 1/3 of the post’s total length deep, plus 6 inches for gravel. Tamp in 6 inches of gravel, brace the post plumb, fill with fast-setting concrete to 3 to 4 inches below grade, add about a gallon of water per 50-pound bag, and wait 4 hours before loading it.
How to Set a Fence Post in Concrete
Photo: U.S. Department of Defense Current Photos Petty Officer 2nd Class Ryan Batchelder/Commander, U.S. 3rd Fleet / Wikimedia Commons, Public domain
Tools & materials

  • Rot-resistant post (pressure-treated wood or galvanized steel)
  • Post-hole digger or auger, shovel
  • Gravel or crushed stone
  • Fast-setting concrete mix (50-lb bags)
  • Level, two 2×4 braces, stakes, screws and a drill
  • Bucket for water
  • Eye protection, gloves and a dust mask

Steps

  1. Call 811 (in Arkansas, Arkansas 811) before you dig. Utilities have two full working days to mark their lines. Know where your property line is, too.
  2. Dig the hole about three times as wide as the post, and about 1/3 of the post’s total length deep, plus 6 inches. Example: for a 6-foot fence, an 8-foot post goes about 32 inches in the ground, so dig about 38 inches. Use a tube form in loose or sandy soil.
  3. Add gravel. Pour about 6 inches of gravel or crushed stone in the bottom and tamp it level. It drains water away from the post’s end.
  4. Set and brace the post. Stand it in the hole, screw braces to two adjacent sides, and stake the other ends of the braces.
  5. Plumb it. Check two adjacent sides with a level, adjust, and fasten the braces to the stakes.
  6. Add concrete. Pour dry fast-setting mix around the post to 3 to 4 inches below the ground. For holes deeper than 2 1/2 feet, fill and water in layers of no more than 2 1/2 feet.
  7. Add water. Pour about 1 gallon of water per 50-pound bag and let it soak in. Recheck plumb right away.
  8. Let it set. It sets in roughly 20 to 40 minutes. Wait about 4 hours before hanging rails or putting heavy loads on it, and longer when it’s cooler than 72°F.
  9. Finish. Backfill the top with soil or sod, sloped away from the post so water runs off.
Safety: Wear eye protection, nitrile gloves and a dust mask when working with dry concrete mix. Hand-dig near any marked utility lines.

From https://www.djgaston.com/set-a-fence-post/ · Updated October 22, 2026