Professional Concrete Calculator
Figure out how many cubic yards or bags of concrete you need for your project. Whether you're pouring a slab, footing, or stairs, our calculator provides accurate estimates for volume, weight, and bag quantities to help you order the right amount.
Project Details
How to Use the Concrete Calculator
- Select your project type (e.g., slab, cylinder, stairs)
- Enter the dimensions using sliders or manual input
- Choose the unit of measurement and adjust for accuracy
- Select the concrete density if it's different from the default
- Click "Calculate" to get volume, weight, and bag requirements
Adjust Dimensions
Pre-mixed
Calculate Concrete
Click to calculate volume, weight, and bag requirements
Common Types of Concrete Projects
Concrete is used in everything from garden paths to garage foundations — but not all projects require the same thickness, reinforcement, or mix strength. Choosing the right type ensures your concrete performs well over time and doesn't crack or crumble under pressure.
Use the guide below to choose the best concrete thickness and mix strength (PSI) for your specific project:
🚶 Sidewalks
🚗 Driveways
🌳 Patios
🏠 Garage Floors
🏗️ Footings
🏢 Slabs on Grade
🪜 Stairs
🧱 Retaining Walls
🚧 Fence Posts
🏗️ Deck Footings / Piers
🔍 Why It Matters
Choosing the wrong PSI or incorrect depth can lead to premature cracking, surface spalling, or structural failure. For example:
- Using patio-grade concrete for a driveway may cause it to break under heavy vehicles.
- Pouring a garage floor without vapor barriers can lead to moisture problems.
Understanding these differences ensures your concrete lasts longer, looks better, and meets local building requirements.
💡 Need help choosing? Our calculator adjusts bag counts and volume for slabs, footings, posts, and more — so you always get the right amount and type.
⚖️ Recommended Concrete Ratios
| Mix Type | Cement | Sand | Gravel | Water |
|---|---|---|---|---|
| General Purpose | 1 | 2 | 3 | ~0.5 |
| High-Strength | 1 | 2 | 2.5 | ~0.45 |
| Lean Mix (Footings) | 1 | 3 | 5 | ~0.6 |
*Ratios are by volume. Adjust water content based on conditions and desired workability.
💡 Pro Concrete Tips
- Always check local building codes for minimum requirements
- Use our calculator above to determine exact volume and bag quantities
- Order 10% extra concrete to account for waste and minor variations
- Consider weather conditions when choosing pour timing
- Ensure proper curing time for maximum strength development
Why Use a Concrete Calculator?
Ordering the right amount of concrete is crucial. If you order too little concrete, you might face delays, extra delivery charges, or weak spots in your pour. Ordering too much concrete wastes money and materials.
Using a concrete calculator lets you:
- Calculate concrete volume in cubic yards or cubic feet
- Estimate how many 80 lb or 60 lb concrete bags you'll need
- Avoid costly overages or shortages
- Plan your budget more accurately
Common Uses
Our handy concrete calculator helps you quickly estimate how much concrete you need for:
- Driveways
- Sidewalks
- Patios
- Footings & foundations
- Columns
How To Calculate Concrete Volume
The basic formula for concrete volume is simple:
For a rectangular slab:
Volume = (Length × Width × Thickness) ÷ 12
- Measure length and width in feet
- Measure thickness in inches
- Divide by 12 to convert thickness to feet
- Multiply to find cubic feet
- Divide by 27 to get cubic yards
Our calculator does the math for you in seconds.
Simply choose your project shape and adjust your measurements using the sliders, buttons, or manual input. Select your preferred units and the tool does the math with automatic conversions.
How Many Bags of Concrete Do You Need?
If you're working on smaller projects, you might use pre-mixed concrete bags. An 80 lb bag covers approximately 0.6 cubic feet.
To find the number of bags:
Bags Needed = Total Cubic Feet ÷ 0.6
Our calculator automatically shows you how many 60 lb or 80 lb bags you'll need for your project.
Frequently Searched Questions About Concrete Calculations:
- How much concrete do I need for a slab?
- How to calculate concrete for a driveway?
- How many bags of concrete for a patio?
- Do I need to order extra concrete?
- How much concrete do I really need?
- How to convert cubic feet of concrete to cubic yards?
Order a Little Extra
It's always smart to order about 10% more concrete than you calculate. This covers spillage, uneven ground, and slight measurement errors. It's better to have extra than come up short during your pour!