How many 80 lb bags is 2 yards of concrete?

Concrete is a common building material used in many construction projects for foundations, driveways, patios, and more. When purchasing concrete, it is typically measured in cubic yards, which refers to the volume of the wet concrete mix. On the other hand, concrete is often sold in 80 lb bags of dry concrete mix which must be mixed with water before use. So how many 80 lb bags of concrete does it take to equal 2 cubic yards of wet concrete? Let’s take a closer look at the math behind this conversion.

Key Things to Know

Here are some key things to understand when converting between yards of concrete and 80 lb bags:

• 1 cubic yard (yd3) of concrete is equal to 27 cubic feet (ft3)
• Dry concrete mix bags are typically sold in 80 lb bags, meaning each bag contains 80 pounds of dry concrete mix
• To convert pounds of dry concrete to cubic feet, you need to know the density. The density of dry concrete mix is approximately 100 pounds per cubic foot (lb/ft3)
• Once water is added and mixed to make wet concrete, it expands in volume. Wet concrete has a density of around 150 pounds per cubic foot (lb/ft3)

The Math Behind Yards to Bags

Let’s walk through the math step-by-step:

1. Start with 2 cubic yards (yd3) of wet concrete
2. Convert yards to feet:
   • 1 yd3 = 27 ft3
   • 2 yd3 = 2 * 27 ft3 = 54 ft3
3. Convert wet concrete in feet to pounds using the density:
   • Density of wet concrete = 150 lb/ft3
   • 54 ft3 * 150 lb/ft3 = 8,100 lbs of wet concrete
4. Convert pounds of wet concrete to pounds of dry concrete mix using ratios:
   • Wet concrete weighs 150 lbs/ft3
   • Dry concrete mix weighs 100 lbs/ft3
   • So if 8,100 lbs wet concrete = 54 ft3
   • Then x lbs dry concrete = 54 ft3
   • Setting up ratio:
     • 8,100 lbs wet concrete / 150 lb/ft3 = 54 ft3
     • x lbs dry concrete / 100 lb/ft3 = 54 ft3
   • Cross multiply and solve:
     • x = 5,400 lbs of dry concrete mix
5. With 80 lb bags:
   • 5,400 lbs dry concrete mix
   • 1 bag = 80 lbs
   • 5,400 lbs / 80 lbs per bag = 67.5 bags
6. Round up = 68 bags

Conclusion

In summary, the math shows that 2 cubic yards of wet concrete is equal to about 68 bags of 80 lb dry concrete mix. This accounts for the expansion in volume that occurs when water is added to the dry mix. So if you need 2 yards of concrete delivered, you would need approximately 68 bags of dry mix if purchasing and mixing separately. Keep in mind there may be some rounding or other minor variations in actual application.

Key Takeaways

• 1 yd3 concrete = 27 ft3
• Dry mix density ~100 lb/ft3
• Wet concrete density ~150 lb/ft3
• 2 yd3 wet concrete = ~8,100 lbs
• 8,100 lbs wet concrete = 5,400 lbs dry mix
• With 80 lb bags, 5,400 lbs = 68 bags

More Examples and Scenarios

Let’s look at some additional examples to further illustrate how to convert between yards of concrete and 80 pound bags:

1 Yard of Concrete in Bags

• Start with 1 yd3 of wet concrete
• 1 yd3 = 27 ft3
• 27 ft3 wet concrete x 150 lb/ft3 = 4,050 lbs
• 4,050 lbs wet concrete = 2,700 lbs dry mix
• 2,700 lbs dry mix / 80 lbs per bag = 33.75 bags
• Round up to 34 bags

So 1 cubic yard of concrete is equal to about 34 bags of 80 lb dry concrete mix.

0.5 Yard of Concrete in Bags

• 0.5 yd3 = 0.5 * 27 ft3 = 13.5 ft3
• 13.5 ft3 wet concrete x 150 lb/ft3 = 2,025 lbs
• 2,025 lbs wet concrete = 1,350 lbs dry mix
• 1,350 lbs dry mix / 80 lbs per bag = 16.875 bags
• Round up to 17 bags

0.5 cubic yard of concrete is equal to about 17 bags of 80 lb dry concrete mix.

3 Yards of Concrete in Bags

• 3 yd3 = 3 * 27 ft3 = 81 ft3
• 81 ft3 wet concrete x 150 lb/ft3 = 12,150 lbs
• 12,150 lbs wet concrete = 8,100 lbs dry mix
• 8,100 lbs dry mix / 80 lbs per bag = 101.25 bags
• Round up to 102 bags

3 cubic yards of concrete is equal to about 102 bags of 80 lb dry concrete mix.

Concrete Bag Calculator

Here is a handy concrete bag calculator you can use:

Yards of Wet Concrete	Bags of 80 lb Dry Concrete Mix
0.25 yd3	9 bags
0.5 yd3	17 bags
0.75 yd3	26 bags
1 yd3	34 bags
1.5 yd3	51 bags
2 yd3	68 bags
2.5 yd3	85 bags
3 yd3	102 bags
4 yd3	136 bags
5 yd3	170 bags
6 yd3	204 bags
7 yd3	238 bags
8 yd3	272 bags
9 yd3	306 bags
10 yd3	340 bags

This table provides estimates of how many 80 lb bags are needed for various yardages of wet concrete. The numbers are rounded up to simplify the results. Use this for a handy reference, but keep in mind the actual bag count may vary slightly based on specific conditions.

Tips for Purchasing and Mixing Concrete

When buying and working with concrete in bags, keep these tips in mind:

• Purchase an extra 10% more bags than calculated to allow for waste or spillage
• Stack bags flat and evenly spaced to prevent lumpiness
• Stage bags close to the mixing area for efficiency
• Follow mixing instructions carefully for water amounts
• Use a power mixer for best results
• Divide total water amount evenly among bags
• Mix thoroughly until uniform consistency is achieved
• Work in batches for easier handling and pouring
• Clean tools and equipment promptly after use before concrete hardens

Proper mixing is critical for bagged concrete to achieve its full strength and durability. Carefully follow manufacturer’s instructions on mixing procedures and times, quantities of water to add, and working times before curing begins.

Frequently Asked Questions

Does bagged or truck concrete have higher quality?

Bagged concrete and truck (ready-mix) concrete both can produce high quality results when properly handled. Truck concrete may have greater consistency since it is mixed thoroughly in a truck mixer. But bagged concrete can also achieve excellent strength and durability when mixed per instructions. For most residential projects, high quality results can be obtained with bagged concrete when care is taken in the mixing and placement process.

Is bagged concrete as strong as ready-mix?

Yes, bagged concrete can be as strong as ready-mix concrete. The ingredients and proportions of cement, sand, and aggregate in a quality bagged mix are designed to achieve a target compressive strength that meets or exceeds most building code requirements. When mixed consistently and allowed to cure properly, the hardened concrete from 80 lb bags can reach over 4,000 psi compressive strength.

What is the ratio of water to concrete in an 80 lb bag?

The typical recommended ratio of water to dry concrete mix in an 80 lb bag is about 5-6 quarts of water per bag. However, it is critical to follow the specific manufacturer’s instructions on the bag or product information for the exact amounts, as this can vary by brand. Using too little water can make the mix unworkable, while too much can weaken the final strength.

What size project can I do with bagged concrete?

Bagged concrete is ideal for many smaller residential projects such as:

• Setting mailbox posts
• Pouring shed foundations
• Creating patios
• Building garden walls
• Setting fence posts
• Fixing steps
• Setting landscaping edges
• Pouring footings
• Leveling floors

For larger projects, truck delivery of ready-mix may be preferable. As a rule of thumb, projects needing less than 2-3 yards of concrete are well-suited to bagged mixes for most homeowners.

The Benefits of Bagged Concrete

Using bagged concrete mix offers a few advantages over truck poured concrete:

• More convenient: Bags are purchased separately when needed and mixed on-site as required
• Better portion control: Mix only what is needed for the task
• Easier access: Can be used in tight spaces or remote areas
• Lower cost: No delivery fee for small jobs
• More customizable: Adjust mix consistency as desired
• Less waste: Unused dry mix can be saved and stored

For any size residential project, bagged concrete offers an affordable and DIY-friendly alternative to ready-mix concrete delivered in a truck.

Conclusion

Figuring out the number of 80 lb bags of concrete required to equal a specific volume in yards can be complicated by the need to convert between wet and dry concrete densities. But by following the steps outlined above, you can accurately calculate the approximate bag equivalent for a yardage amount.

As a handy reference:

• 1 yd3 concrete = 34 bags
• 2 yd3 concrete = 68 bags
• 3 yd3 concrete = 102 bags

This allows you to conveniently estimate the number of 80 lb bags needed for a project. Combine this with tips on proper mixing and handling, and you’ll be ready to take on your next concrete project using bagged mixes.