How Many Bags of Concrete Per Fence Post

The short answer

Budget about two 50-pound bags of fast-setting concrete per hole for a standard residential fence post, per Sakrete's Post & Pole Setting project guide. That figure holds for roughly a 4-inch post in a 10-inch-diameter hole set 2 feet deep, the geometry in Quikrete's older spec-data sheet worked example. Quikrete's current data sheet uses a different worked example (a 3-inch square post in a 9-inch hole, 30 inches deep) and reaches the same 2-bag figure; see the next section. Wider posts or deeper holes need more bags. Use the volume method below to size a hole that doesn't match those dimensions.

What Quikrete's data sheets say

Quikrete publishes two worked examples for its Fast-Setting Concrete Mix, and they don't match. Quikrete's current Fast-Setting Concrete Mix data sheet (Product No. 1004-50, revised November 2025) states that 2 bags of 50-pound Fast-Setting Concrete Mix set a 3-inch square post in a 9-inch-diameter hole, 30 inches deep. Quikrete's older Fast-Setting Concrete spec-data sheet, still live at its own URL, makes the same "2 bags" claim for a different hole: a 4-inch round post in a 10-inch-diameter hole, 2 feet deep. Both documents are current Quikrete publications, so use whichever example is closer to your own post and hole.

Quikrete's standard Concrete Mix (Product No. 1101, revised October 2022, a different product from the fast-setting mix above) gives bag yield but no bags-per-hole example. Per that data sheet, a 40-pound bag yields 0.30 cubic feet, a 50-pound bag yields 0.375 cubic feet, a 60-pound bag yields 0.45 cubic feet, an 80-pound bag yields 0.60 cubic feet, and a 90-pound bag yields 0.675 cubic feet of mixed concrete. Use these yields with the volume formula below.

What Sakrete's data sheets say

Sakrete's Fast Setting Concrete Mix technical data sheet (Rev. 05/18) publishes a bags-by-depth table for a 10-inch-diameter hole using 50-pound bags: 1.25 bags at 12 inches deep, 2 bags at 18 inches, 2.5 bags at 24 inches, and 3 bags at 30 inches. Sakrete's Post & Pole Setting project guide gives a simpler rule of thumb: about 2 bags of Fast Setting Concrete per hole for a standard 6-foot fence post, without tying that figure to a specific hole diameter or depth.

Sakrete's High-Strength Concrete Mix technical data sheet, covering its standard non-fast-setting line, gives yields instead of a bags-per-hole table: 0.30 cubic feet for a 40-pound bag, 0.45 cubic feet for a 60-pound bag, 0.60 cubic feet for an 80-pound bag, and 0.66 cubic feet for a 90-pound bag. Sakrete doesn't sell a 50-pound bag in this line, since its standard mix jumps from 40 pounds to 60 pounds.

Sizing a hole that doesn't match a worked example

Every published worked example assumes a specific post size and hole depth. If yours is different, calculate it directly. Find the hole's volume with the cylinder formula, pi times radius squared times depth, subtract the volume the post itself displaces, then divide by your product's per-bag yield from the tables above.

Sakrete's own bags-by-depth table supports this method. Raw cylinder volume for a 10-inch hole at 12 inches deep predicts about 1.43 bags at Sakrete's 0.38-cubic-foot yield, but Sakrete's table lists 1.25 bags for that depth. The gap tracks with the post taking up space inside the hole, so subtracting post volume first gets closer to Sakrete's own numbers.

Brand and product matter more than you'd expect

Fast-setting and standard mixes yield different amounts per bag, and the two brands don't always publish matching figures for an equivalent product. Quikrete's fast-setting 50-pound bag yields 0.375 cubic feet. Sakrete's fast-setting 50-pound bag yields 0.38 cubic feet. The difference is small, but don't average the two brands together or apply one brand's bags-per-hole table to the other brand's product. Use the yield and worked example that match the bag you're actually buying.

Estimates disclaimer

These figures come directly from Quikrete's and Sakrete's published data sheets and project guides, current as of this writing. Actual concrete use varies with soil conditions and how closely your dig matches the manufacturer's assumptions. Treat every number on this page as a planning estimate, not an engineered quantity, and buy an extra bag before you start. For post count and concrete sized to your specific run, use the concrete post calculator or the full fence calculator.

FAQ

How many bags of concrete does one fence post need?

About 2 bags of 50-pound fast-setting concrete per hole for a standard residential post, per Sakrete's Post & Pole Setting project guide. Quikrete's spec-data sheet gives the same 2-bag figure for a 4-inch post in a 10-inch hole set 2 feet deep. Deeper or wider holes need more.

Do Quikrete and Sakrete concrete bags yield the same amount?

Close, but not identical. Quikrete's Fast-Setting Concrete Mix yields 0.375 cubic feet per 50-pound bag. Sakrete's Fast Setting Concrete Mix yields 0.38 cubic feet per 50-pound bag. Use the figure for the specific product you're buying rather than treating the two brands as interchangeable.

How much does a 60-pound bag of concrete cover?

A 60-pound bag yields about 0.45 cubic feet of mixed concrete, a figure that matches across Quikrete's standard Concrete Mix, Quikrete's Fast-Setting Concrete Mix, and Sakrete's High-Strength Concrete Mix data sheets.

Should I subtract the post's volume before calculating bags?

Yes. Sakrete's own bags-by-depth table yields fewer bags than raw cylinder-volume math predicts, a gap consistent with the post displacing space inside the hole. Subtract the post's cross-sectional volume from the hole's volume before dividing by bag yield.

Yard & Board guides and tools give planning estimates, not professional advice. Building codes and site conditions vary — confirm structural work with your local permit office or a licensed contractor.