How Much Concrete for 10 Fence Posts? (2026 Guide)
How much concrete for 10 fence posts? Standard 4×4 posts in regular 8–10 in × 30 in holes need about 8 bags of 80-lb mix or 10–11 bags of 60-lb.
The fence rule: 0.8 bag per post
A standard 4×4 post in a hand-dug hole that's 8–10 in wide at the top and about 30 in deep swallows roughly 0.5 cf of concrete — the post and the hole's taper leave less space than the top width suggests. An 80-lb bag yields about 0.60 cf and a 60-lb bag about 0.45 cf, so one post uses about 0.8 of an 80-lb bag. For ten posts:
- 80-lb: 10 × 0.8 = 8 bags (about 4.8 cf total).
- 60-lb: 4.8 ÷ 0.45 ≈ 10.7 → 10–11 bags (buy 11).
The 0.8-bag shorthand assumes a typical tapered hole; straight-sided power-auger holes or frost-line-deep holes take more — see the tables below for exact totals.
Concrete per hole by hole size
Holes usually run about three times the post's width. Treating each hole as a full, uniform cylinder at auger width (plus a small allowance for the flared top and spillage), the pour per hole is:
| Post-hole size (Ø × depth) | Concrete per hole | 80-lb bags per post |
|---|---|---|
| 8 in × 24 in | 0.87 cf | ≈1.5 |
| 8 in × 30 in | 1.09 cf | ≈1.8 |
| 10 in × 30 in | 1.70 cf | ≈2.8 |
| 10 in × 36 in | 2.04 cf | ≈3.4 |
Bags per post = cf ÷ 0.60, rounded. Soil matters too: loose, sandy ground sloughs into the hole (dig wider), while firm clay holds tight. In frost zones the hole must sit below the frost line — often 36 in or deeper in northern states — so measure your depth and let the concrete calculator do the bag math.
Bags for exactly 10 posts
Same hole for all ten? These totals assume exactly ten 4×4 posts in 80-lb bags:
| Post-hole size (4×4 post) | 80-lb bags for 10 posts |
|---|---|
| 8 in × 24 in | 15 |
| 8 in × 30 in | 18 |
| 10 in × 30 in | 28 |
| 10 in × 36 in | 34 |
Worked example: ten 4×4 posts in 8 in × 30 in holes → 1.09 cf each → about 1.8 bags per post → 10 × 1.8 ≈ 18 bags of 80-lb mix. Planning totals — round up and add one spare at the store. Still deciding how many posts you need? Run the fence calculator first, then size the pour.
Setting tips for a 10-post run
- Dig below the frost line — stopping above it lets frost heave lift the post by spring, and that extra depth is why the deeper rows take more bags.
- Add 3–4 in of gravel at the bottom — it drains the post base and gives a level spot to set the post before pouring.
- Fast-setting vs regular mix — fast-setting concrete pours dry into a wet hole and sets in about 20–40 minutes, ideal for bracing a post plumb; standard mix allows longer working time but needs a tub for a ten-post run.
- Slope the top of each pour away from the post so rain can't pool against the wood, and set the post plumb before the mix sets.
Planning the whole fence? See how much concrete fence posts need for the general rule, and count your boards with how many fence pickets you need once the posts are set.
FAQ
How many bags of concrete do I need for 10 fence posts?
About 8 bags of 80-lb mix — or 10–11 bags of 60-lb — for standard 4×4 posts in ordinary 8–10 in × 30 in holes. That's the fence rule of about 0.8 bag per post (80-lb ≈ 0.60 cf, 60-lb ≈ 0.45 cf). Buy 9 of the 80-lb size so you have a spare for the last hole.
How much does the hole size change the total for 10 posts?
A lot. Sized as full, uniform cylinders, ten posts in 8×24-in holes total about 15 bags of 80-lb, while 10×36-in holes total about 34 bags — each wider or deeper step adds bags fast. Frost-line depth in cold regions is why holes often run 30–36 in or deeper.
How many bags of concrete does one fence post need?
A typical 4×4 post takes about 0.8 of an 80-lb bag (roughly 0.5 cf). Across common tapered holes, plan on about 0.8–1.7 bags per post; sized as a full cylinder, an 8×24-in hole runs about 1.5 bags and a 10×36-in hole about 3.4 — so measure your holes before you buy.
Setting a different number of posts?
Our free calculators give you the exact answer in seconds.