Concrete Bag Calculator
Find the exact number of 40, 60, or 80 lb bags for your project - with cost estimates.
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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.
You need about 45 bags of 80 lb concrete, 60 bags of 60 lb, or 90 bags of 40 lb to fill one cubic yard (27 ft³). Each 80 lb bag yields 0.6 ft³, a 60 lb bag 0.45 ft³, and a 40 lb bag 0.30 ft³. Enter your dimensions above for an exact count.
Finishing the pour yourself?
A steel finishing trowel smooths the surface once the concrete is placed.
Finishing trowel on AmazonHow the Bag Count Is Measured
Concrete Bag Yield, Pallet & Cost by Size
Different bag sizes yield different volumes. This is the one-stop reference for how much each bag covers, how many fill a cubic yard, and how many come on a full pallet:
| Bag Size | Yield per Bag | Bags per Cubic Yard | Bags per Pallet | Approx. Retail Price |
|---|---|---|---|---|
| 80 lb | 0.60 ft³ | 45 bags | 42 bags | ~$6.50 each |
| 60 lb | 0.45 ft³ | 60 bags | 56 bags | ~$5.00 each |
| 40 lb | 0.30 ft³ | 90 bags | 80 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 need less mixing time; smaller bags are easier to carry. Pallet counts are standard for Quikrete and Sakrete - confirm with your supplier before ordering a full pallet.
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 (base) | 80 lb Bags (+10%) |
|---|---|---|---|---|
| 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 | 6 bags |
| Sidewalk section | 4 × 20 ft | 4" | 45 bags | 49 bags |
| Patio | 10 × 10 ft | 4" | 56 bags | 62 bags |
| Single-car driveway | 10 × 20 ft | 5" | 139 bags | 153 bags |
Base is the exact count (Volume ÷ 0.60); the +10% column adds a waste allowance - order that. Over ~90 bags, compare ready-mix.
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.
Spec & Standards Notes
- Packaged dry concrete mix - its composition, compressive-strength classes, and bag labeling - is governed by ASTM C387/C387M. Most general-purpose bagged mixes are rated around 4,000 PSI at 28 days.ASTM C387/C387M
- Bag yield (0.60 / 0.45 / 0.30 ft³ for 80 / 60 / 40 lb) is the manufacturer-stated value printed on the bag. Confirm against the label before buying, since yield varies slightly by product and mix density.
Concrete bag project cost guide (2026)
| Project | Bags needed | Material cost | Notes |
|---|---|---|---|
| 10x10 ft patio (4 in) | 56x 80 lb bags | $300-$420 | DIY-friendly with mixer rental |
| 12x12 ft patio (4 in) | 80x 80 lb bags | $440-$600 | Standard small patio |
| 20x20 ft garage slab (4 in) | 223x 80 lb bags | $1,300-$1,800 | Ready-mix more cost-effective at this size |
| Fence post per post (fast-set) | 2x 50 lb bags | $10-$16 | Fast-set mix is sold in 50 lb bags; no mixing |
| 8-in sonotube (2 ft deep) | 2x 80 lb bags | $12-$18 | Standard deck pier footing |
| 12-in sonotube (3 ft deep) | 4x 80 lb bags | $24-$36 | Larger structural post |
80 lb bags run $6-$8 at home improvement stores (2026). For slabs over 1 cubic yard (~300 sq ft at 4 in), ready-mix concrete at $150-$200/yd delivered is almost always cheaper than bags.
After You Know Your Bag Count
Bag count is one piece of the pour. Here is the usual sequence from here:
Comparing bag totals against a full installed price? See what a concrete slab actually costs in 2026 - per square foot, per cubic yard, broken down by size and region.
Related Calculators
Calculate the slab or footing volume first, then use this tool. Browse the construction calculator collection.