Concrete Calculator: Yards to Bags

This calculator converts concrete volume in cubic yards into the number of 60-lb or 80-lb bags you need, and also shows the total weight and cubic feet. Enter the volume in cubic yards (or the dimensions of your project), and you get the bag count for both common bag sizes instantly.

Formula

The core formula is straightforward: Number of bags = (Volume in cubic yards × 27) ÷ Volume per bag (in cubic feet). Because 1 cubic yard equals 27 cubic feet, you first convert yards to cubic feet, then divide by the bag’s yield.

• V (cubic yards) – the volume you need to fill, as entered.
• 27 – conversion factor: 1 cubic yard = 27 cubic feet.
• Bag yield – a 60-lb bag of concrete mix yields about 0.45 cubic feet; an 80-lb bag yields about 0.6 cubic feet. These are standard industry values (e.g., Quikrete, Sakrete).

So, for 60-lb bags: bags = (V × 27) / 0.45; for 80-lb bags: bags = (V × 27) / 0.6. Always round up to the next whole bag because you can’t buy a fraction of a bag.

Worked Example

Using the default volume of 1 cubic yard:

1. Convert to cubic feet: 1 × 27 = 27 cubic feet.
2. For 60-lb bags: 27 ÷ 0.45 = 60 bags.
3. For 80-lb bags: 27 ÷ 0.6 = 45 bags.
4. Total weight: 60 bags × 60 lb = 3,600 lb; 45 bags × 80 lb = 3,600 lb. (Both equal 1 yard of concrete, which weighs roughly 3,600–4,000 lb.)

So, for 1 cubic yard, you need 60 of the 60-lb bags or 45 of the 80-lb bags. The calculator rounds up automatically, so if your volume is not a whole number, you’ll get the next full bag count.

How to Use This Calculator

Enter the volume of concrete you need in cubic yards. If you don’t know the volume, measure the project’s length, width, and thickness (all in feet), multiply them together to get cubic feet, then divide by 27 to get cubic yards. For example, a 10 ft × 10 ft slab that is 4 inches thick (0.333 ft) is 10 × 10 × 0.333 = 33.3 cubic feet = 1.23 cubic yards. Enter 1.23 and the calculator will tell you the bags needed.

This tool is handy for small to medium projects like shed bases, footings, or patio slabs where you’re buying bagged mix rather than ordering a ready-mix truck. For large jobs (more than 2–3 cubic yards), ready-mix is usually cheaper and less labor-intensive.

Choosing the Right Bag Size

Bagged concrete comes in several sizes, but 40-lb, 60-lb, and 80-lb are the most common. The 80-lb bags are the most economical per cubic foot, but they are heavy—many people can’t lift them comfortably. The 60-lb bags are a good middle ground for most DIYers. The 40-lb bags are easier to handle for small repairs but cost more per yard. Consider your physical strength and how many bags you can mix at once (usually one at a time in a wheelbarrow or mixer).

Common Mistakes and How to Avoid Them

• Mixing up units: Always convert inches to feet (divide by 12) before calculating volume. A 4-inch slab is 0.333 ft, not 4 ft.
• Not rounding up: Always round up to the nearest whole bag. If you need 59.2 bags, buy 60. Under-ordering means a trip back to the store.
• Ignoring waste: Add 5–10% extra for spillage, uneven subgrade, or miscalculations. For a 1-yard project, that’s 3–6 extra 60-lb bags.
• Assuming bag yield is exact: The 0.45 and 0.6 cubic feet are nominal. Actual yield can vary slightly with mixing water, but the difference is negligible for most jobs.
• Forgetting the weight: A yard of concrete weighs about 3,600–4,000 lb. If you’re mixing by hand, that’s a lot of lifting. Plan for breaks or rent a mixer.

Cost and Quantity Comparison

While prices vary by region and brand, 80-lb bags generally cost less per cubic yard than 60-lb bags. For example, if an 80-lb bag costs $5, a yard costs $225; if a 60-lb bag costs $4, a yard costs $240. The 80-lb bags also mean fewer bags to handle (45 vs. 60 for a yard). However, the 60-lb bags are easier for one person to lift and mix. For a small project like a single post footing, the difference is minimal; for a 2-yard slab, the 80-lb bags can save both money and trips.

Safety and Mixing Tips

Concrete mix contains Portland cement, which is caustic. Wear gloves, long sleeves, and eye protection when handling dry mix or wet concrete. Avoid breathing dust. Mix only as much as you can place in about 30 minutes—concrete sets quickly, especially in warm weather. Add water gradually; too much water weakens the concrete. Use a wheelbarrow or a mechanical mixer for volumes over a few bags. Clean tools immediately after use, as hardened concrete is very difficult to remove.

Alternatives to Bagged Concrete

For larger projects, ready-mix concrete delivered by truck is often more practical and cost-effective. A typical minimum order is 1 cubic yard, and you avoid the labor of mixing dozens of bags. However, you must be ready to place and finish the concrete quickly, often within an hour. Another alternative is using concrete mix with additives (like fiber-reinforced) for specific applications, but the bag yield remains the same. For very small repairs, a pre-mixed concrete patch or mortar mix may be easier, but those are not designed for structural slabs.

Frequently Asked Questions

How many 80-lb bags are in a cubic yard? 45 bags. Because 1 cubic yard is 27 cubic feet, and an 80-lb bag yields 0.6 cubic feet: 27 ÷ 0.6 = 45.

How many 60-lb bags are in a cubic yard? 60 bags. 27 cubic feet ÷ 0.45 cubic feet per bag = 60.

How do I calculate concrete for a slab? Measure length, width, and thickness in feet (convert inches to feet by dividing by 12). Multiply them to get cubic feet, then divide by 27 to get cubic yards. For example, a 10×10 slab, 4 inches thick: 10×10×0.333 = 33.3 cu ft = 1.23 cu yd.

Can I mix bags in a wheelbarrow? Yes, for one bag at a time. Add water, then mix with a hoe or shovel. For multiple bags, rent a concrete mixer to save time and effort.

What is the weight of a cubic yard of concrete? Approximately 3,600–4,000 pounds, depending on mix and moisture. That’s about 1.8–2 tons.

Should I order extra bags? Yes, add 5–10% for waste. If you need 45 bags, buy 48–50 to cover spills, uneven subgrade, or miscalculations.

Related

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• Building Square Footage Calculator: How to Measure
• Building Square Calculator: How to Find Area

in vol | Volume | cubic yards | 1 | 0
out bags60 | 60-lb bags | bags | ceil(vol * 27 / 0.45) | 0
out bags80 | 80-lb bags | bags | ceil(vol * 27 / 0.6) | 0
out weight60 | Total weight (60-lb) | lb | bags60 * 60 | 0
out weight80 | Total weight (80-lb) | lb | bags80 * 80 | 0
out cubicft | Volume | cubic feet | vol * 27 | 1