If you’re pouring a small concrete slab, setting fence posts, building a footing, or completing another DIY project, you may be wondering how many bags of concrete for 5 cubic feet. Knowing the correct number of bags helps you avoid running out of material or overspending on unnecessary concrete.
The answer depends on the weight and yield of each bag. Concrete bags come in several standard sizes, and each produces a different amount of finished concrete after mixing with water.
For example, you’ll need approximately:
- 34 bags of 40 lb concrete
- 28 bags of 50 lb concrete
- 23 bags of 60 lb concrete
- 17 bags of 80 lb concrete
to make 5 cubic feet of finished concrete.
This guide includes yield charts, easy calculations, real-world examples, and expert tips to help you buy the right amount of concrete for your project.
Quick Answer
Here are the approximate numbers of concrete bags needed for 5 cubic feet:
| Bag Size | Yield per Bag | Bags Needed for 5 Cubic Feet |
|---|---|---|
| 40 lb | 0.15 cu ft | 34 bags |
| 50 lb | 0.18 cu ft | 28 bags |
| 60 lb | 0.22 cu ft | 23 bags |
| 80 lb | 0.30 cu ft | 17 bags |
Always round up to the nearest whole bag since partial bags are impractical.
Concrete Bag Yield Chart
Different bag sizes produce different amounts of mixed concrete.
| Bag Weight | Approximate Yield |
|---|---|
| 40 lb | 0.15 cubic feet |
| 50 lb | 0.18 cubic feet |
| 60 lb | 0.22 cubic feet |
| 80 lb | 0.30 cubic feet |
These yields may vary slightly by manufacturer, but they are widely accepted averages.
40 lb Concrete Bags
A 40-pound bag yields approximately 0.15 cubic feet.
Calculation:
5 ÷ 0.15 = 33.3
Round up:
34 bags
50 lb Concrete Bags
A 50-pound bag produces approximately 0.18 cubic feet.
Calculation:
5 ÷ 0.18 = 27.8
Round up:
28 bags
60 lb Concrete Bags
Each 60-pound bag yields about 0.22 cubic feet.
Calculation:
5 ÷ 0.22 = 22.7
Round up:
23 bags
80 lb Concrete Bags
An 80-pound bag produces approximately 0.30 cubic feet.
Calculation:
5 ÷ 0.30 = 16.7
Round up:
17 bags
Most contractors prefer 80-pound bags because fewer bags are needed, reducing mixing time.
How to Calculate Bags of Concrete
You can calculate concrete requirements in three simple steps.
Step 1 – Determine the Total Volume
Measure your project and calculate its volume in cubic feet.
For example:
- Length = 5 ft
- Width = 2 ft
- Thickness = 0.5 ft
Volume = 5 cubic feet
Step 2 – Check the Bag Yield
Look at the yield listed on the concrete bag. Most manufacturers print the expected finished volume on the packaging.
Step 3 – Divide the Total Volume
Use this formula:
Bags Needed = Total Cubic Feet ÷ Yield per Bag
Always round up to ensure you have enough material.
Concrete Bag Calculator Table
Use this quick-reference chart for a 5 cubic foot project.
| Bag Weight | Yield | Bags Required |
|---|---|---|
| 40 lb | 0.15 cu ft | 34 |
| 50 lb | 0.18 cu ft | 28 |
| 60 lb | 0.22 cu ft | 23 |
| 80 lb | 0.30 cu ft | 17 |
Common Projects That Need About 5 Cubic Feet
A total volume of 5 cubic feet is suitable for many small projects, including:
- Small concrete pads
- Garden walkways
- Mailbox posts
- Fence posts
- Deck footings
- Shed foundations
- Patio repairs
- Outdoor steps
Knowing the required volume before purchasing materials helps reduce waste and saves money.
Should You Buy Extra Concrete?
Yes. It’s a good idea to purchase 5–10% extra concrete to account for:
- Uneven ground
- Minor spills
- Over-excavation
- Measurement errors
- Waste during mixing
For a 5-cubic-foot project, buying one extra bag is usually sufficient.
Expert Tips
- Measure your project carefully before purchasing concrete.
- Use larger bags if you’re comfortable lifting them—they reduce the number of bags needed.
- Mix only as much concrete as you can place before it begins to set.
- Follow the manufacturer’s recommended water ratio.
- Have all tools ready before mixing.
- Work in manageable batches for better consistency.
- Store unused bags in a dry location.
Common Mistakes
Avoid these common concrete calculation errors:
Forgetting to Round Up
Always round to the next whole bag.
Ignoring Waste
Ordering the exact amount leaves no margin for mistakes.
Using Incorrect Bag Yields
Different bag weights produce different amounts of finished concrete.
Measuring Incorrectly
Small measurement errors can significantly affect the total volume.
Adding Too Much Water
Excess water weakens the finished concrete.
FAQs
1. How many 80 lb bags of concrete do I need for 5 cubic feet?
You’ll need 17 bags, since each 80-pound bag yields approximately 0.30 cubic feet.
2. How many 60 lb bags are needed for 5 cubic feet?
Approximately 23 bags are required.
3. Should I buy extra concrete?
Yes. Purchase an additional 5–10% to cover waste and unexpected variations.
4. How much concrete does one 50 lb bag make?
A standard 50-pound bag yields about 0.18 cubic feet of finished concrete.
5. Can I mix different bag sizes?
Yes. You can combine different bag weights as long as the total finished concrete volume meets your project requirements.
Conclusion
If you’re wondering how many bags of concrete for 5 cubic feet, the answer depends on the size of the bags you purchase. For most projects, you’ll need approximately 34 (40 lb), 28 (50 lb), 23 (60 lb), or 17 (80 lb) bags to produce 5 cubic feet of finished concrete.
Before buying materials, calculate your project’s volume accurately, verify the yield printed on the concrete bags, and purchase a little extra to account for waste. With proper planning, you’ll have enough concrete to complete your project efficiently without unnecessary delays or extra trips to the store.
