Concrete Bag Calculator: How Many 40, 50, 60 or 80 lb Bags
A 10×10 ft slab at 4 in needs 62 bags of 80 lb concrete or 82 bags of 60 lb with 10% extra; one 80 lb bag makes 0.6 cubic feet.
Advanced options: waste, prices
NRMCA advises ordering 4 to 10 percent over the estimate.
Concrete needed (with 10% extra)
1.96 yd³
1.50 m³ · 48 ft³ before extra
Slab: 12 ft × 12 ft × 4 in. Over about 1 yd³: order ready-mix.
Premix bags
- 80 lb88
- 60 lb118
- 50 lb141
- 40 lb176
- Ready-mix cost
- $313
- Weight
- 7,200 lb
Full breakdown
| Volume before extra | 1.78 yd³ · 1.36 m³ |
|---|---|
| With 10% extra | 1.96 yd³ |
| Weight (150 lb/ft³) | 7,200 lb · 3.60 tons |
| Pallets of 40 lb (80 bags each) | 3 |
| Pallets of 60 lb (56 bags each) | 3 |
| Pallets of 80 lb (42 bags each) | 3 |
| Truckloads at 12 yd³ | 1 |
| Truckloads at 8 yd³ | 1 |
Bag counts round up, as Quikrete's own calculator does. Cost uses your prices; delivery and short-load fees are extra.
Key takeaways
- 80 lb bag = 0.6 ft³, 60 lb = 0.45, 50 lb = 0.375, 40 lb = 0.3 (Quikrete).
- 1 yd³ = 45 bags of 80 lb.
- A 10×10 slab at 4 in = 62 bags of 80 lb with extra.
- Quikrete pallets: 42 × 80 lb, 56 × 60 lb, 80 × 40 lb.
How Many Bags of Concrete Do I Need?
You need the concrete volume in cubic feet, plus 10% extra, divided by the bag yield, rounded up. A 10×10 ft slab at 4 in holds 33.33 ft³; with 10% extra that is 36.67 ft³, and 36.67 ÷ 0.6 = 61.1, so 62 bags of 80 lb mix.
How Much Concrete Does One Bag Make?
One bag of concrete mix makes 0.3 to 0.6 cubic feet, depending on its weight; the yields below come from Quikrete's own calculator.
| Bag | Yield (ft³) | Yield (yd³) | Bags per yd³ |
|---|---|---|---|
| 80 lb | 0.6 | 0.022 | 45 |
| 60 lb | 0.45 | 0.017 | 60 |
| 50 lb | 0.375 | 0.014 | 72 |
| 40 lb | 0.3 | 0.011 | 90 |
How Many Square Feet Does a Bag of Concrete Cover?
One 80 lb bag of concrete covers 1.8 sq ft at 4 in thick; thinner pours cover more.
| Bag | 2 in thick | 3 in thick | 4 in thick |
|---|---|---|---|
| 80 lb | 3.60 sq ft | 2.40 sq ft | 1.80 sq ft |
| 60 lb | 2.70 sq ft | 1.80 sq ft | 1.35 sq ft |
| 50 lb | 2.25 sq ft | 1.50 sq ft | 1.13 sq ft |
| 40 lb | 1.80 sq ft | 1.20 sq ft | 0.90 sq ft |
How Many Cubic Feet Are in an 80 lb Bag of Concrete?
An 80 lb bag of concrete mix makes 0.6 cubic feet, a 60 lb bag 0.45 ft³ and a 50 lb bag 0.375 ft³, according to Quikrete's calculator; half a yard (13.5 ft³) therefore takes 23 bags of 80 lb mix before extra.
How to Calculate Bags of Concrete
Calculate bags of concrete in four steps.
- Find the volume in cubic feet (length × width × thickness in feet).
- Add 10% for waste.
- Divide by the bag yield: 0.6 ft³ for 80 lb, 0.45 for 60 lb, 0.375 for 50 lb, 0.3 for 40 lb.
- Round up to a whole bag, as Quikrete's calculator does.
Bags of Concrete for Common Projects
Bag counts for common projects, with 10% extra, come from the same engine as the calculator.
| Project | yd³ with 10% | 80 lb bags | 60 lb bags | 50 lb bags | 40 lb bags |
|---|---|---|---|---|---|
| 10×10 ft slab, 4 in | 1.36 | 62 | 82 | 98 | 123 |
| 12×12 ft slab, 4 in | 1.96 | 88 | 118 | 141 | 176 |
| 4×4 post, 12 in hole, 2 ft | 0.06 | 3 | 4 | 5 | 6 |
| 12 in sonotube, 4 ft | 0.13 | 6 | 8 | 10 | 12 |
| 20 ft footing, 12×6 in | 0.41 | 19 | 25 | 30 | 37 |
How Many Bags for a 100 sq ft Slab?
A 100 sq ft slab at 4 in needs 62 bags of 80 lb concrete or 82 bags of 60 lb, with 10% extra.
How Many Bags of Concrete on a Pallet?
A pallet of Quikrete Concrete Mix holds 42 bags of 80 lb, 56 bags of 60 lb or 80 bags of 40 lb, according to Quikrete. Quikrete's Fast-Setting Concrete Mix comes 56 bags of 50 lb per pallet. Store counts can vary, so confirm before ordering.
Sakrete's rule of thumb is that one pallet of bags is about a cubic yard of concrete; 42 bags of 80 lb mix make 25.2 ft³, a little under the 27 ft³ in a yard.
80 lb vs 60 lb vs 40 lb Bags: Which Size to Buy?
80 lb bags mean fewer bags and trips, and lighter bags are easier to lift and mix by hand. Per cubic foot, the volume is the same; compare price per bag ÷ yield to find the cheaper size at your store.
When to Stop Buying Bags and Order Ready-Mix
Stop buying bags at about 1 cubic yard, which is this calculator's own rule: past that point you would mix 45 bags of 80 lb, or 3,600 lb, by hand. Compare costs on bags or ready-mix.
How Many Bags of Concrete per Cubic Meter?
One cubic meter is 35.31 ft³, so it takes 59 bags of 80 lb concrete or 79 bags of 60 lb, before extra.
Worked Examples: Bags for Three Projects
4×8 ft pad at 4 in. 10.67 ft³; with 10% extra, 20 bags of 80 lb or 27 of 60 lb.
4×4 ft AC pad at 4 in. 5.33 ft³; with 10% extra, 10 bags of 80 lb.
8 in sonotube 4 ft deep. 1.40 ft³; with 10% extra, 3 bags of 80 lb or 4 of 60 lb.
How Much Water for an 80 lb Bag of Concrete?
Use the amount printed on the bag, adding water slowly: too much water makes weak concrete, according to NRMCA and the University of Illinois mix guide.
Concrete Bag Calculator FAQ
How much will a 60 lb bag of concrete cover?
A 60 lb bag makes 0.45 ft³, which covers 1.35 sq ft at 4 in thick or 2.7 sq ft at 2 in.
How many cubic feet will a 50 lb bag of concrete cover?
A 50 lb bag makes 0.375 ft³ of concrete, about 1.1 sq ft at 4 in thick.
How many cement bags are in a 100 sq ft slab?
A 100 sq ft slab at 4 in (33.33 ft³) needs about 9 bags of 94 lb Portland cement at 1:2:3, or 62 bags of 80 lb premix concrete; see the cement calculator.
Next step
If the count passes about 45 bags, compare a truck on bagged concrete vs ready-mix; otherwise check brand yields on the Quikrete calculator.
Official sources
Last reviewed 2026-11-05. Numbers come from our tested engine; see how we calculate and our sources.