Concrete Bag Yields by Bag Size

A bag of concrete mix is sold by weight, but what you need to know is how much finished concrete it makes. That figure is the bag's yield: the volume of concrete one bag produces when mixed as directed. Yield is set by each manufacturer for each product, and it is printed on the bag and the product data sheet.

Yield is volume per bag, and it varies by product

Two bags of the same weight do not always make the same volume. Each manufacturer measures and publishes the yield for its own product, and the figures are not interchangeable. The safe rule is simple: use the yield printed for the exact product and bag size you are buying.

Once you know the yield, two conversions answer most questions:

bags per ft³ = 1 ÷ yield (ft³ per bag)
bags per yd³ = 27 ÷ yield (ft³ per bag)
bags needed  = volume (ft³) ÷ yield, rounded up to a whole bag

Published yields by product

The table lists yields from QUIKRETE and Sakrete data sheets. The last three columns are computed from the published yield. Bags per cubic yard are shown before rounding; round up when you buy.

Liters are converted from the published cubic-foot yield using 1 ft = 0.3048 m exactly, so they may differ slightly from the rounded metric figure printed on a bag.

Why the two 90 lb bags differ

At 80 lb, QUIKRETE Concrete Mix and Sakrete High-Strength Concrete Mix list the same yield: 0.6 ft³. At 90 lb they part ways. QUIKRETE lists 0.675 ft³ (noted as a regional size), and Sakrete lists 0.66 ft³.

QUIKRETE 90 lb ÷ 80 lb weight ratio: 90 ÷ 80 = 1.125
QUIKRETE 80 lb yield × ratio:        0.6 × 1.125 = 0.675 ft³ (matches 0.675)
Sakrete 80 lb yield × ratio:         0.6 × 1.125 = 0.675 ft³ (published: 0.66)
Difference per 90 lb bag:            0.675 − 0.66 = 0.015 ft³

QUIKRETE's 90 lb yield scales in direct proportion to its 80 lb yield. Sakrete's does not; its published 90 lb figure is a little lower. The data sheets do not explain the difference, and this guide does not guess at a reason. The practical point is that you cannot take one brand's yield and apply it to another brand's bag of the same weight.

The gap is small per bag, but it adds up. Per cubic yard, it is 40 bags versus 40.9 bags, a difference of about 0.9 bags.

Worked example: a 10 × 10 ft pad, 4 in thick

First find the volume, then divide by each bag's yield.

Area   = 10 ft × 10 ft = 100 ft²
Depth  = 4 in ÷ 12 = 0.3333 ft
Volume = 100 × 0.3333 = 33.333 ft³ (1.235 yd³)

80 lb QUIKRETE:    33.333 ÷ 0.6 = 55.56 → 56 bags
90 lb QUIKRETE:    33.333 ÷ 0.675 = 49.38 → 50 bags
90 lb Sakrete:     33.333 ÷ 0.66 = 50.51 → 51 bags

The two 90 lb bags give different counts for the same pad. This example has no allowance for spillage or an uneven base. Add one that fits your site before you buy. Measure the actual form height too: if a 4 in slab averages thicker, the bag count rises in proportion.

Combining two bag sizes

Sometimes a store runs short of one size, or you have bags left from another job. Work out how much volume the bags you have will supply, then size the rest with the second product's yield.

On hand   = 40 × 0.6 ft³ = 24 ft³
Shortfall = 33.333 − 24 = 9.333 ft³
60 lb bags = 9.333 ÷ 0.45 = 20.74 → 21 bags

Never count a 60 lb bag as three-quarters of an 80 lb bag by habit. In this product line the ratio happens to hold (0.45 ÷ 0.6 = 0.75), but the 90 lb comparison above shows that weight ratios and yield ratios do not always line up.

Weight is not volume

It is tempting to buy concrete mix by total weight, for example “about a ton.” That works only if you convert back to volume with the published yield of the exact product. Weight tells you what you will lift and haul. Yield tells you how much space the concrete will fill. Plan the job with yield, and use weight to plan the trips and the vehicle load.

Metric conversion

One foot is exactly 0.3048 m, so one cubic meter is 1 ÷ 0.3048³ = 35.3147 ft³. To find bags for a metric volume, convert to cubic feet and divide by the yield.

Volume = 0.5 m³ × 35.3147 = 17.657 ft³
Bags   = 17.657 ÷ 0.6 = 29.43 → 30 bags
Per m³ = 35.3147 ÷ 0.6 = 58.9 bags of 80 lb

Tips for using yields

• Read the yield on the bag you actually buy. Store shelves can carry several brands and sizes side by side.
• Do not mix yields. If you buy some 60 lb and some 80 lb bags, total the volume each group supplies separately.
• Round up to whole bags only once, at the end, after adding any allowance.
• Fast-setting and high-strength mixes are separate products with their own yields. QUIKRETE lists its Fast-Setting Concrete Mix at 0.375 ft³ per 50 lb bag.
• On larger jobs, compare the bag count with a bulk ready-mix order. See bagged vs. bulk materials and planning a material delivery.

To size a full slab with an allowance and get bag counts for every product above at once, use the slab volume and bag count tool. For converting between cubic feet, cubic yards, and cubic meters, see what a cubic yard is.