Concrete Bag Calculator
Estimate how many bags of concrete you may need for your project. Enter your project dimensions or a known volume, and select your bag size (40-lb, 50-lb, 60-lb, or 80-lb).
Last reviewed: June 2026
10% waste is standard for mixing loss and spill pages.
Results update automatically as you enter measurements.
Your Material List
For this project, buy or order approximately
Use these quantities as a shopping list, supplier note, quote check, or quick jobsite material estimate.
Formula and Assumptions
Formula used
When calculating by dimensions, volume in cubic feet = length × width × thickness in feet. To estimate bags, the calculator divides total cubic feet, including your waste factor, by the estimated yield of the selected bag size. Typical yields are 0.60 ft^3 for 80-lb, 0.45 ft^3 for 60-lb, 0.375 ft^3 for 50-lb, and 0.30 ft^3 for 40-lb bags.
Unit conversions
Inches are converted to feet before volume is calculated. Cubic feet are converted to cubic yards by dividing by 27. Bag counts are rounded up because stores do not sell partial bags.
Waste factor explanation
Waste factor helps account for uneven surfaces, cuts, spills, compaction, settling, and measurement differences. The right buffer depends on your project and material.
Material Assumptions and Disclaimer
Bag yield or density assumptions
- Calculations assume standard manufacturer bag yields. Actual yields may vary slightly by brand or mix type.
- If using dimension mode, we assume the subgrade form is rectangular.
Estimate disclaimer
These tools are useful for DIY planning and quick jobsite estimates, but the results are still estimates. Verify quantities for structural work, code requirements, supplier material specs, product labels, or professional requirements before purchasing or quoting a job.
When to be careful
- Concrete bags are extremely heavy. Make sure your vehicle or trailer is rated for the payload (an average pallet weighs over 3,000 lbs).
Example Calculation
For a 5ft x 5ft AC unit pad that is 4 inches thick. Using 60-lb bags and a 10% waste factor:
- Convert 4 inches to feet: 4 ÷ 12 = 0.333 ft
- Base volume: 5 × 5 × 0.333 = 8.333 ft^3
- Add 10% waste: 8.333 × 1.10 = 9.167 ft^3
- Divide by bag yield: 9.167 ÷ 0.45 = 20.37 bags
- Round up to the nearest whole bag: 21 bags needed.
You need 21 60-lb bags.
Frequently Asked Questions
How many bags of concrete is in a cubic yard?
Since there are 27 cubic feet in a cubic yard, you need about forty-five 80-lb bags (27 / 0.6), sixty 60-lb bags (27 / 0.45), or ninety 40-lb bags (27 / 0.3) to make one cubic yard.
How many 80-lb bags are on a pallet?
A common pallet of 80-lb bags contains 42 bags, weighing about 3,360 lbs. Be sure your vehicle can handle this payload.
What is the yield of a single 60-lb bag of concrete?
A standard 60-lb bag of concrete mix yields approximately 0.45 cubic feet when mixed with water.
When should I have a concrete truck deliver instead of using bags?
Any project requiring more than 1 cubic yard of concrete (over 45 80-lb bags) is much easier to have delivered via a ready-mix truck. Hand mixing large quantities is labor-intensive and often risks cold joints in your project.
How do I know my true bag yield?
While 0.60, 0.45, and 0.30 cubic feet are standard rules of thumb, specialized mixes like "high-yield" or lightweight concrete might produce more volume per bag. Check the back of the specific product bag for the manufacturer's rated yield.
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