How Much Concrete Does a Bag Make? (40/50/60/80 lb Yields Explained)

The quick answer: yield by bag size

QUIKRETE's data sheet for its standard Concrete Mix (No. 1101) lists these approximate yields. Sakrete publishes the same figures for its 40, 60 and 80 lb High-Strength mix.

Two things jump out. First, an 80 lb bag makes only 0.6 cubic feet — less than a 5-gallon bucket holds (about 0.67 cubic feet). Second, yield scales exactly with weight: every size works out to roughly 133 lb of dry mix per cubic foot of finished concrete, so a 40 lb bag makes exactly half of what an 80 lb bag does.

How many bags make a cubic yard?

A cubic yard is 27 cubic feet (3 ft × 3 ft × 3 ft). Divide 27 by the yield and you get 45 bags of 80 lb mix, 60 bags of 60 lb, 72 bags of 50 lb or 90 bags of 40 lb. Sakrete's estimating guide makes the same point in plain terms: it takes 45 bags of 80 lb mix “to hit a cubic yard dead on.”

You will sometimes see 75 bags per yard quoted for 50 lb bags. That corresponds to a yield of 0.36 cubic feet; QUIKRETE's published figure of 0.375 gives 72. On a small job the difference is two or three bags, which your waste allowance covers anyway.

The square-foot shortcut, and why it rounds up

For the most common job — a 4-inch slab — Sakrete offers a rule of thumb: one square foot of slab takes one 50 lb bag, 0.8 of a 60 lb bag or 0.6 of an 80 lb bag. It also notes that one cubic yard poured 4 inches deep covers 81 square feet.

Run the numbers and the shortcut is slightly generous. A square foot at 4 inches is 1 × 1 × 0.333 = 0.333 cubic feet, which is exactly 0.56 of an 80 lb bag, 0.74 of a 60 lb bag and 0.89 of a 50 lb bag. Rounding those up to 0.6, 0.8 and 1 builds in about 8%–13% extra, which lines up with the next piece of advice.

Add 10% — the yield assumes a perfect pour

Published yields describe concrete in a container, not in a real form. Forms bow slightly, the ground under a slab dips, and some mix stays in the wheelbarrow and on the tools. Sakrete says it is “always a good idea to add 10% to every estimate.” Running out halfway through a pour is worse than having a bag left over: fresh concrete placed against concrete that has already started to set forms a weak cold joint.

Worked example: a 10 × 10 ft patio

Volume: 10 × 10 × (4 ÷ 12) = 33.33 cu ft
With 10% extra: 33.33 × 1.10 = 36.67 cu ft
80 lb bags: 36.67 ÷ 0.60 = 61.1 → 62 bags
60 lb bags: 36.67 ÷ 0.45 = 81.5 → 82 bags

That is 62 × 80 lb bags — nearly 4,960 lb of mix to lift, carry and mix by hand. The concrete calculator does this math for slabs, footings, round columns and steps, and compares every bag size side by side.

Bags for post holes and small jobs

Post holes are where most people buy bagged concrete. QUIKRETE and Sakrete both size the hole at about three times the width of the post, so a 4×4 post (actually 3½ in square) goes in a hole about 10½ in across. For a 6 ft fence, Sakrete suggests burying about a third of the above-ground height, or 2 ft.

Hole: π × (10.5 ÷ 2)² × 24 = 2,078 cu in
Minus the post: 3.5 × 3.5 × 24 = 294 cu in
Concrete: 1.03 cu ft → 2 × 80 lb or 4 × 50 lb bags per post, with 10% extra

Sakrete's own post guide says about two bags of its Fast Setting mix per hole for a standard fence; the exact count depends on how wide and deep you really dig. The fence calculator multiplies this out for every post in the run.

Three common estimating mistakes

• Mixing up inches and feet. A 4 in slab is 0.333 ft thick, not 4. Entering 4 as feet makes the estimate twelve times too big.
• Forgetting the depth below grade. Footings and post holes are measured from the bottom of the hole, not from ground level.
• Buying the exact count. With no allowance for waste, one uneven spot in the base can leave you a bag short at the end of the pour.

Which bag size is the best buy?

Compare price per cubic foot, not price per bag. Using the median shelf prices we collected in September 2026, 80 lb bags came out cheapest per cubic foot. But store pricing varies: Home Depot listed QUIKRETE's 80 lb bag at $6.47 and its 60 lb bag at $4.85, which is $10.78 per cubic foot either way. When the price per cubic foot is the same, choose the bag you can comfortably handle — smaller bags are easier to lift into a mixer and pour in steady batches.

At some size, bags stop making sense. A cubic yard of 80 lb bags costs about $321 at our median price, while delivered ready-mix runs $110–$150 per yard plus a short-load fee of about $40–$60 per yard on small orders. See the concrete cost guide for the full price tables.

Other numbers on the bag worth knowing

• Minimum thickness: QUIKRETE Concrete Mix is meant for pours 2 inches thick or more.
• Strength: 4,000 psi at 28 days, per the data sheet.
• Water: start with about 3–7 pints per bag depending on the bag size, adding more only as the instructions allow. Extra water makes mixing easier but weakens the finished concrete.
• Curing: keep the concrete damp for 5 days in warm weather (70 °F and up) or 7 days between 50 and 70 °F.

Always follow the directions printed on the bag you buy; formulas and instructions differ between products such as fast-setting and high-strength mixes.

Sources

• QUIKRETE Concrete Mix No. 1101 product data sheet accessed 2026-09-17
• Sakrete High-Strength Concrete Mix product page accessed 2026-09-16
• Sakrete — Estimating bagged concrete jobs accessed 2026-09-17
• QUIKRETE — Setting posts (project sheet) accessed 2026-09-16
• Sakrete — Setting posts & poles accessed 2026-09-16
• The Home Depot — Concrete Mix category listing accessed 2026-09-16
• Angi — Concrete delivery cost accessed 2026-09-17 · page dated 2026-09-10
• HomeGuide — Concrete prices accessed 2026-09-17 · page dated 2026-01-06