Concrete Bag Yield: 40, 50, 60 and 80 lb Bags Explained
An 80 lb bag of concrete mix makes about 0.60 cu ft, a 60 lb bag 0.45 cu ft and a 40 lb bag 0.30 cu ft, according to the manufacturer's data sheet for a standard US mix. That's 45 bags of 80 lb per cubic yard. A metric 20 kg bag of a similar mix makes roughly 9 to 10 litres, so about 100 to 110 bags per cubic metre.
US bag sizes
| Bag | Yield | Bags per cubic yard | Bags per m³ |
|---|---|---|---|
| 40 lb | 0.3 cu ft | 90 | 117.7 |
| 50 lb | 0.375 cu ft | 72 | 94.2 |
| 60 lb | 0.45 cu ft | 60 | 78.5 |
| 80 lb | 0.6 cu ft | 45 | 58.9 |
| 90 lb | 0.675 cu ft | 40 | 52.3 |
Every size works out at the same ratio: about 0.0075 cu ft of concrete per pound of dry mix. That's why a bag's yield scales with its weight.
Metric bag sizes
Metric bags vary more between brands and mixes. Applying the same weight-to-volume ratio gives these estimates; the yield printed on your bag is always the better figure.
| Bag | Estimated yield | Bags per m³ |
|---|---|---|
| 20 kg | 9.4 L | 107 |
| 25 kg | 11.7 L | 85 |
| 30 kg | 14 L | 71 |
| 40 kg | 18.7 L | 53 |
Some makers state about 10 litres per 20 kg bag (100 bags per cubic metre). The difference is small for a few post holes but adds up on a slab, so the calculator uses the more cautious figure. We compared published yields across four countries in Concrete Bag Yields Compared: 20 kg bags range from about 8.4 to 11 litres.
Why yield matters
- Different products, different yields. Fast-setting, high-strength and fibre-reinforced mixes may not match standard mix. Read the bag.
- Weight is not volume. Two 40 lb bags make the same as one 80 lb bag, but the price per cubic foot can differ.
- Round up. Running short mid-pour leaves a weak joint where fresh concrete meets concrete that has started to set.
Got a bag with a different yield? In the calculators, choose Other size and enter the figure from the label.
