Concrete Bag Calculator
Find the exact number of 40, 60, or 80 lb bags for your project — with cost estimates.
Your Bag Estimate
- Enter dimensions — length, width, and thickness of your pour area.
- Select thickness — use presets for common projects or enter a custom depth.
- Set waste — 10% covers most situations. Increase for uneven ground.
- Read bag counts — the calculator shows exact counts for 80, 60, and 40 lb bags.
- Decide bags vs mix — under 1 cubic yard, bags are practical. Above 2, order ready-mix.
Bags per Cubic Yard by Size
Different bag sizes yield different volumes. Knowing the yield per bag helps you compare costs between sizes and decide which to buy:
| Bag Size | Yield per Bag | Bags per Cubic Yard | Approx. Retail Price |
|---|---|---|---|
| 80 lb | 0.60 ft³ | 45 bags | ~$6.50 each |
| 60 lb | 0.45 ft³ | 60 bags | ~$5.00 each |
| 40 lb | 0.30 ft³ | 90 bags | ~$3.75 each |
Price per cubic yard: 80 lb bags ≈ $293, 60 lb bags ≈ $300, 40 lb bags ≈ $338. Larger bags are more cost-efficient and require less mixing time.
When to Use Bags vs. Ready-Mix
Bagged concrete makes sense for small projects where you need precision and flexibility — fence posts, small pads, repairs, and any pour under about 1 cubic yard. You can mix at your own pace and don't need to coordinate delivery timing.
Once you pass 2 cubic yards (roughly 90 bags of 80 lb mix), ready-mix delivery becomes the better option. The per-yard cost drops to $150–$200 compared to $290+ with bags, and you avoid hours of manual mixing. Most plants charge a short-load fee for orders under 3 yards, typically $30–$50 per yard under the minimum.
Quick Reference: Bag Counts by Project
| Project | Size | Thickness | 80 lb Bags |
|---|---|---|---|
| Fence post hole | 10" diameter × 36" deep | — | 2 bags |
| Mailbox post | 12" diameter × 24" deep | — | 2 bags |
| Small pad | 3 × 3 ft | 4" | 5 bags |
| Sidewalk section | 4 × 20 ft | 4" | 37 bags |
| Patio | 10 × 10 ft | 4" | 56 bags |
| Single-car driveway | 10 × 20 ft | 5" | 139 bags |
Includes 10% waste. For projects over 50 bags, consider ready-mix delivery instead.
Formulas Used in This Calculator
The calculator converts your dimensions to cubic feet, then divides by each bag's coverage:
With waste = Volume × (1 + Waste %)
80 lb bags = Volume (ft³) ÷ 0.60
60 lb bags = Volume (ft³) ÷ 0.45
40 lb bags = Volume (ft³) ÷ 0.30
Cubic yards = Volume (ft³) ÷ 27
Always round up to the next whole bag. Having one or two extra bags on hand is cheaper than making a second trip.
Related Calculators
Calculate the slab or footing volume first, then use this tool. Browse the construction calculator collection.
Frequently Asked Questions
How many 80 lb bags of concrete make a yard?
It takes approximately 45 bags of 80 lb concrete to make one cubic yard. Each 80 lb bag yields about 0.6 cubic feet, and one cubic yard equals 27 cubic feet (27 ÷ 0.6 = 45).
Can I mix different bag sizes together?
Yes. All standard concrete bags use the same basic mix formula — the only difference is the amount per bag. You can freely mix 40, 60, and 80 lb bags in the same pour. Just make sure each batch is mixed to the same water ratio for consistent strength.
What are the dimensions of a 60 lb concrete bag?
A standard 60 lb concrete bag measures approximately 24–26 inches long × 16–18 inches wide × 3–5 inches thick when laid flat. Quikrete 60 lb bags are typically around 24\" × 17\" × 4\". Dimensions vary slightly by brand and production run. A full pallet of 60 lb bags holds 56 bags and stands about 48 inches tall. Store bags off the ground and away from moisture — even humidity causes partial setting.
What are the dimensions of an 80 lb concrete bag?
A standard 80 lb concrete bag measures approximately 20 inches long × 13 inches wide × 6 inches thick when flat. An 80 lb bag is noticeably heavier to handle than a 60 lb bag — on large projects, many DIYers prefer 60 lb bags to reduce strain. A full pallet holds 42 bags of 80 lb mix.
How much concrete does a bag yield?
Bag yield depends on bag size and brand, but a common rule of thumb is: 80 lb ≈ 0.60 ft³, 60 lb ≈ 0.45 ft³, and 40 lb ≈ 0.30 ft³. Check the bag label for the manufacturer's stated yield and use that for the most accurate estimate.