Figuring out how many bags of concrete you need for a project is important for planning and saving money. So, how many bags of concrete are in a cubic yard? A cubic yard holds about 27 cubic feet of material. The exact number of concrete bags calculation depends on the size and concrete bag yield of the bags you use. For example, an 80 lb bag of concrete typically yields about 0.6 cubic feet, meaning you would need roughly 45 to 46 of these bags for one cubic yard. A 60 lb bag yields about 0.45 cubic feet, requiring around 60 bags per cubic yard. This article will break down the steps to figure out exactly how much concrete you need in bag form, explaining cubic feet per bag and how to make sure you buy the right amount.
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Fathoming Concrete Volume
Before we talk about bags, let’s picture a cubic yard concrete volume. Imagine a box that is 3 feet wide, 3 feet long, and 3 feet tall. That box holds one cubic yard of space. Concrete volume is measured this way, even if it’s for a flat slab or a long footing.
Why measure concrete in cubic yards?
* It’s a standard measure for bigger jobs.
* It helps keep track of material amounts.
* It makes pricing easier for large batches.
But concrete bags are sold by weight and tell you how many cubic feet per bag they make when mixed. So, we need to go from cubic yards to cubic feet.
Moving From Cubic Yards to Cubic Feet
A cubic yard is a good big unit. A cubic foot is smaller. To know how many small units fit into a big unit, we multiply.
* 1 yard = 3 feet
* 1 cubic yard = 1 yard × 1 yard × 1 yard
* 1 cubic yard = 3 feet × 3 feet × 3 feet
* 1 cubic yard = 27 cubic feet
So, one cubic yard is always equal to 27 cubic feet. This is the first key number for our number of concrete bags calculation. Whatever project size you figure out in cubic yards, just multiply that number by 27 to get the volume in cubic feet.
Example:
* Need 0.5 cubic yards? That’s 0.5 × 27 = 13.5 cubic feet.
* Need 2 cubic yards? That’s 2 × 27 = 54 cubic feet.
This step, converting cubic yard to cubic feet, is essential before you can figure out how many bags are needed because bag yields are given in cubic feet.
Figuring Out Concrete Bag Yield
Every bag of concrete mix tells you how much volume it will fill once it’s mixed with water. This is called the concrete bag yield. This yield is usually given in cubic feet. Different bag sizes have different yields. Also, different types of concrete mix (like standard concrete, high-strength, or quick-setting) can have slightly different yields even if the bag weight is the same.
The most common bag sizes you’ll find are 80 pounds, 60 pounds, and 40 pounds.
Let’s look at the typical yield for these common sizes:
- 80 lb concrete bag yield: An 80-pound bag of standard concrete mix usually makes about 0.6 cubic feet of concrete. This is a very common size for jobs like fence posts, small slabs, or repairing steps.
- 60 lb concrete bag yield: A 60-pound bag of standard concrete mix typically yields about 0.45 cubic feet. These bags are lighter and easier to carry, good for smaller tasks or places where lifting is hard.
- 40 lb concrete bag yield: A 40-pound bag of standard concrete mix usually makes about 0.3 cubic feet. These are often used for very small repairs or projects where you only need a little bit of concrete.
It is important to check the bag itself, as the exact concrete bag yield can vary a little bit between brands and mix types. For instance, Quikrete bag yield figures are often listed on their website or on the bag itself. A standard Quikrete 80 lb concrete bag yield is typically listed as 0.6 cubic feet, and their 60 lb bag yields 0.45 cubic feet, matching the typical numbers.
Knowing the cubic feet per bag is the second key piece of information you need.
The Calculation: Getting the Number of Concrete Bags
Now we have the two main numbers:
1. The total volume of concrete needed in cubic feet (from your cubic yard conversion).
2. The yield of one concrete bag in cubic feet (cubic feet per bag).
To find the total number of concrete bags calculation, you divide the total volume needed by the volume one bag makes:
Number of Bags = Total Volume Needed (in cubic feet) / Yield Per Bag (in cubic feet)
Let’s do an example. Suppose you need 1 cubic yard of concrete. We know 1 cubic yard is 27 cubic feet.
Example Calculation 1: Using 80 lb Bags
* Total volume needed: 27 cubic feet (for 1 cubic yard)
* Yield per 80 lb bag: 0.6 cubic feet (this is the typical 80 lb concrete bag yield)
* Number of Bags = 27 cubic feet / 0.6 cubic feet per bag
* Number of Bags = 45 bags
So, you would need about 45 80 lb bags to make one cubic yard of concrete.
Example Calculation 2: Using 60 lb Bags
* Total volume needed: 27 cubic feet (for 1 cubic yard)
* Yield per 60 lb bag: 0.45 cubic feet (this is the typical 60 lb concrete bag yield)
* Number of Bags = 27 cubic feet / 0.45 cubic feet per bag
* Number of Bags = 60 bags
So, you would need about 60 60 lb bags to make one cubic yard of concrete.
Example Calculation 3: For a Smaller Job
Let’s say you need concrete for a footing that measures 1 foot wide, 1 foot deep, and 10 feet long.
* Volume needed = Width × Depth × Length
* Volume needed = 1 ft × 1 ft × 10 ft = 10 cubic feet.
Now, let’s use 80 lb bags (0.6 cubic feet yield).
* Number of Bags = 10 cubic feet / 0.6 cubic feet per bag
* Number of Bags = 16.67 bags
Since you can’t buy part of a bag, you would need to round up. In this case, you would buy 17 bags. It’s always best to round up to make sure you have enough.
These calculations show how much concrete does one bag make relative to the total needed volume. Using the bag’s listed yield and the total required cubic yard concrete volume (converted to cubic feet) makes the number of concrete bags calculation simple.
Grasping Why Yield Can Change Slightly
The yield number printed on a concrete bag is a good estimate. However, the real amount of mixed concrete you get from a bag can vary a little bit. This is normal and usually not a big problem, but it’s why people often buy an extra bag or two.
What can cause small changes in yield?
* How much water you add: Adding too much water makes the concrete weaker and can slightly increase the volume, but this is bad practice. Adding the correct amount of water is important for strength.
* How well you mix: Making sure all the powder is mixed well with the water helps achieve the stated yield.
* Material packing: Sometimes, how the dry mix settles in the bag can slightly affect the final mixed volume, though this is usually minor.
* Moisture: If the mix has picked up some moisture before mixing, it might affect the final consistency and potentially the yield. Store concrete bags in a dry place!
Because of these small possible changes, the stated concrete bag yield is a close average. Relying on it is fine, but having a little extra is a smart backup plan.
Laying Out Common Concrete Bag Yields
It’s helpful to have a quick list of typical yields for common bag sizes. Remember to check the actual bag you buy, as figures can vary by brand (like different Quikrete bag yield numbers for special mixes).
Here is a simple concrete bag size yield chart for standard concrete mix:
| Bag Size (Weight) | Typical Yield (Cubic Feet) | Approx. Bags per Cubic Yard (27 cu ft / Yield) |
|---|---|---|
| 40 pounds | 0.3 | 27 / 0.3 = 90 bags |
| 50 pounds | 0.37 | 27 / 0.37 = ~73 bags |
| 60 pounds | 0.45 | 27 / 0.45 = 60 bags |
| 80 pounds | 0.6 | 27 / 0.6 = 45 bags |
This chart clearly shows how many bags you’d need per cubic yard based on common bag sizes and their typical cubic feet per bag yield. It answers how much concrete does one bag make in terms of its contribution to a cubic yard volume.
Calculating Your Required Concrete Volume
Before you can figure out bags, you need to know the cubic yard concrete volume you require for your specific project. This means measuring the area where the concrete will go and figuring out its volume.
Here’s how to calculate volume for common shapes:
For Rectangular Slabs, Footings, or Paths:
This is the most common shape. You need the length, width, and depth (or thickness). Make sure all your measurements are in the same units, preferably feet.
- Measure the Length (in feet).
- Measure the Width (in feet).
- Measure the Depth or Thickness (in feet). Note: If you measure thickness in inches, divide by 12 to get feet (e.g., 4 inches / 12 = 0.333 feet).
- Volume (in cubic feet) = Length × Width × Depth.
Example: A patio slab 10 feet long, 8 feet wide, and 4 inches thick.
* Length = 10 feet
* Width = 8 feet
* Depth = 4 inches / 12 inches/foot = 0.333 feet
* Volume = 10 ft × 8 ft × 0.333 ft = 26.64 cubic feet.
Now you have the volume in cubic feet. To convert this to cubic yards (which is useful for larger projects or talking to suppliers), you divide by 27:
* Volume in cubic yards = 26.64 cubic feet / 27 cubic feet/cubic yard = 0.987 cubic yards.
This shows you need almost one cubic yard concrete volume. You would then use the 26.64 cubic feet figure for your bag calculation.
For Round Footings (Like for Posts):
You need the diameter (distance across the circle) and the depth.
1. Measure the Diameter (in feet).
2. Find the Radius by dividing the diameter by 2 (Radius = Diameter / 2).
3. Measure the Depth (in feet).
4. Volume (in cubic feet) = π (pi, about 3.14159) × Radius × Radius × Depth.
Example: A footing that is 1 foot across (diameter) and 3 feet deep.
* Diameter = 1 foot
* Radius = 1 foot / 2 = 0.5 feet
* Depth = 3 feet
* Volume = 3.14159 × 0.5 ft × 0.5 ft × 3 ft = 2.356 cubic feet.
You would then use this 2.356 cubic feet figure for your bag calculation.
Taking the time to accurately measure and calculate your required cubic yard concrete volume (and then convert to cubic feet) is the very first step in figuring out the number of concrete bags calculation.
A Simple Path to Your Bag Count
Let’s put it all together in clear steps for calculating the number of concrete bags you need.
Step-by-Step Guide to Calculating Bags:
- Measure Your Area: Get the length, width, and depth (or height) of the space you need to fill with concrete. Use a tape measure.
- Use the Same Units: Make sure all your measurements are in feet. If you measured inches, divide inches by 12 to turn them into feet.
- Calculate Total Volume: Multiply Length × Width × Depth to get the volume in cubic feet for rectangular areas. Use the circle formula for round areas. This gives you the total cubic feet per bag capacity needed overall.
- Convert to Cubic Yards (Optional but helpful): If you want to see the volume in cubic yards, divide your total cubic feet by 27. This shows your required cubic yard concrete volume.
- Find Bag Yield: Check the bag of concrete you plan to buy. Look for the concrete bag yield or cubic feet per bag number. For example, an 80 lb concrete bag yield is typically 0.6 cubic feet. A 60 lb concrete bag yield is typically 0.45 cubic feet. Look up Quikrete bag yield if using that brand.
- Do the Math: Divide your total volume needed (from Step 3, in cubic feet) by the yield of one bag (from Step 5, in cubic feet). This is your core number of concrete bags calculation.
- Number of Bags = Total Cubic Feet Needed / Yield Per Bag (Cubic Feet)
- Round Up: You can’t buy part of a bag. Always round your answer up to the next whole number. If your calculation is 16.67 bags, buy 17. If it’s exactly 45 bags, buy 45 or 46 to be safe.
- Buy Extra: It is very wise to buy one or two extra bags more than your calculated number. This covers small errors in measurement, variations in yield, or spills. Running out of concrete during a pour is a major problem!
Following these steps helps ensure you have the right amount of concrete for your project. It translates your needed cubic yard concrete volume into the practical number of concrete bags calculation.
Why Getting the Bag Count Right Matters
Ordering too many bags wastes money. You have to pay for them, transport them, and then figure out what to do with the leftovers. Concrete mix has a shelf life, especially if it gets damp.
Ordering too few bags is often worse. If you run out of concrete in the middle of pouring a slab or footing, the concrete you’ve already poured will start to set. Adding new concrete later might create a weak spot or a visible line (called a cold joint). This can ruin the project’s strength and look.
Accurate calculation using concrete bag yield, converting cubic yard to cubic feet, and carefully doing the number of concrete bags calculation helps you avoid these problems. Knowing how much concrete does one bag make directly impacts your project’s success.
Looking at Different Concrete Mixes
Most standard concrete mixes (often called concrete mix, which contains gravel) will have yields similar to the numbers shown in our chart. However, there are other types of bagged mixes:
- Mortar Mix: Used for laying bricks or blocks. It contains sand and cement, but no gravel. It will have a different yield than concrete mix.
- Mortar Repair Mix: Similar to mortar, for patching. Different yield.
- Asphalt Patch: For fixing blacktops. Completely different material and yield.
- Specialty Concrete Mixes: High-early strength, flowable mixes, etc. These might have slightly different yields listed on the bag compared to standard mixes. Always check the concrete bag yield on the specific bag you buy.
Our focus is on standard concrete mix bags containing cement, sand, and gravel, used for structural work like slabs and footings. The yield calculations discussed here apply best to those types of bags, like typical Quikrete bag yield for their concrete mixes.
Beyond Bags: When to Consider Ready-Mix
For very large projects, mixing dozens or even hundreds of bags of concrete by hand or with a small mixer is a huge amount of work and time. It might also be more expensive than ordering ready-mix concrete.
Ready-mix concrete is mixed at a plant and delivered to your site in a large truck. You order it by the cubic yard.
When might ready-mix be a better choice?
* Projects needing many cubic yards (e.g., large patios, driveways, foundations).
* When you need concrete quickly and consistently.
* When you don’t want to handle and mix many bags.
Mixing concrete from bags is good for:
* Small jobs (fence posts, small repairs, small slabs).
* When access for a large truck is difficult.
* When you need very small amounts.
* When you can work at your own pace.
For projects requiring a cubic yard concrete volume or more, comparing the cost and labor of bags versus ready-mix is a good idea. Our number of concrete bags calculation shows that even just one cubic yard requires a significant number of bags (45-60 typically).
Achieving the Stated Bag Yield
To make sure you get the volume the bag promises (cubic feet per bag), follow the mixing directions carefully.
- Use the right amount of water: The bag will usually give a range. Use the amount suggested for the best strength and yield. Too much water weakens the concrete and can make the yield less predictable.
- Mix completely: Make sure there are no dry pockets of mix. Mix until the color and texture are uniform.
- Mix on a clean surface or in a clean mixer: Don’t lose material during mixing.
Proper mixing helps ensure that the concrete bag yield you calculated with is actually what you get.
Dealing with Leftovers or Coming Up Short
Even with careful calculation using 80 lb concrete bag yield or 60 lb concrete bag yield, sometimes things happen.
If you have leftover dry bags:
* Store them in a dry place, off the ground.
* They can last for several months if kept dry.
* You can use them for future small projects.
If you mix too much concrete:
* You can’t save mixed concrete once it starts hardening.
* Have a plan for extra mix – maybe fill a small hole, make a stepping stone, or have a spot to dump it. Check local rules for disposal.
If you run short during a pour:
* This is the worst situation. If it’s a very small amount needed to finish, you might be able to quickly mix another bag if you have one ready.
* For larger shortages, you might have to stop, let the concrete set, and then pour the rest later, creating a cold joint. This might not be acceptable for some projects.
* This is why buying those extra bags is cheap insurance!
Planning your cubic yard concrete volume and doing the number of concrete bags calculation accurately, then adding a buffer, is the best way to avoid these problems.
Chart Review: Quick Bag Count Estimates
Let’s look again at our concrete bag size yield chart as a quick reference:
| Bag Size (Weight) | Typical Yield (Cubic Feet) | Approx. Bags per Cubic Yard (27 cu ft / Yield) |
|---|---|---|
| 40 pounds | 0.3 | ~90 bags |
| 50 pounds | 0.37 | ~73 bags |
| 60 pounds | 0.45 | 60 bags |
| 80 pounds | 0.6 | 45 bags |
This chart helps visualize how much concrete does one bag make in the context of a larger volume like a cubic yard. Need 1 cubic yard? You need about 45 of the big bags or 60 of the medium ones. Need half a cubic yard? You’ll need about half that number of bags. Need 2 cubic yards? Double the numbers! Remember to check the specific bag’s yield and round up your final count. This simplifies figuring out the number of concrete bags calculation once you know your total cubic yard concrete volume.
Getting the Job Done
Planning your concrete project means more than just figuring out the material. Think about:
* Tools needed (shovels, wheelbarrow, mixer, finishing tools).
* Safety gear (gloves, safety glasses, dust mask).
* How you will mix the concrete.
* How you will get the concrete into place.
* How you will finish the surface.
* How you will cure the concrete (keeping it damp as it hardens).
All these steps are important for a successful concrete job. But it all starts with knowing how much concrete you need, and for bagged mixes, that means knowing exactly how many bags of concrete in a cubic yard and how to calculate the right amount for your specific project volume. Using the bag’s stated concrete bag yield (like 80 lb concrete bag yield or 60 lb concrete bag yield), converting cubic yard to cubic feet, and performing the number of concrete bags calculation is the first crucial step. Always remember to check the specific Quikrete bag yield or yield of whatever brand you choose, as slight differences exist. Rely on a concrete bag size yield chart for quick estimates, but use the bag’s listed yield for the final calculation. Knowing how much concrete does one bag make compared to your total need prevents costly mistakes.
Frequently Asked Questions
h4 Is the yield always exactly what the bag says?
No, the yield listed on the bag (concrete bag yield) is a good estimate based on typical conditions. Small things like the amount of water you add or how well you mix can cause slight variations. This is why it’s smart to buy a little extra.
h4 How much concrete does one bag of Quikrete make?
The amount of concrete a Quikrete bag yield depends on its size and mix type. For standard concrete mixes:
* An 80 lb Quikrete bag typically yields about 0.6 cubic feet (80 lb concrete bag yield).
* A 60 lb Quikrete bag typically yields about 0.45 cubic feet (60 lb concrete bag yield).
* A 40 lb Quikrete bag typically yields about 0.3 cubic feet.
Always check the specific bag for its stated cubic feet per bag.
h4 How do I convert cubic yards to cubic feet for my calculation?
One cubic yard to cubic feet conversion is simple: 1 cubic yard equals 27 cubic feet. To find the cubic feet for any volume measured in cubic yards, just multiply the number of cubic yards by 27. For example, 0.5 cubic yards is 0.5 * 27 = 13.5 cubic feet. This is a key step in the number of concrete bags calculation.
h4 What is concrete bag yield?
Concrete bag yield is the total volume of mixed, ready-to-use concrete that you get from one bag of dry mix. It’s usually measured in cubic feet per bag. This number is needed to figure out how many bags you need for a specific volume like a cubic yard concrete volume.
h4 Should I buy exactly the number of bags I calculate?
It is highly recommended to buy at least one or two extra bags more than your calculation shows. This acts as a safety net in case of small measurement errors, spills, or slight variations in concrete bag yield. Running out is much worse than having a little bit left over.
h4 Does the type of concrete mix affect the yield?
Yes, different types of bagged mixes like standard concrete, mortar mix, or specialty concrete mixes (e.g., high-strength) will have different yields even for the same bag weight. Always check the concrete bag yield listed on the specific bag you are buying to get the correct cubic feet per bag figure for your number of concrete bags calculation. Using a concrete bag size yield chart provides general estimates, but the bag is the final source.
h4 How much area will an 80 lb bag of concrete cover?
The area an 80 lb bag covers depends on the thickness of the concrete layer. Since an 80 lb concrete bag yield is about 0.6 cubic feet, you can figure out the area by dividing the yield by the thickness (in feet).
* For a 4-inch thick slab (0.333 feet), one 80 lb bag covers about 0.6 cu ft / 0.333 ft = ~1.8 square feet.
* For a 6-inch thick slab (0.5 feet), one 80 lb bag covers about 0.6 cu ft / 0.5 ft = 1.2 square feet.
This shows how much concrete does one bag make in terms of covering a flat area at a specific depth. You would need to do this calculation for the total area and thickness, then use the total volume to find the number of bags.