Concrete Calculator
Use our free concrete calculator online to estimate cement, mix ratios, and concrete volume for any project. Calculate slabs, footings, driveways, patios, and foundations with precision. Perfect for DIY home improvement and professional construction planning to save time and money.
Slab Diagram
Result
Enter dimensions and click Calculate to see results.
Complete Guide to Calculating Concrete for Your Projects
Whether you're planning a DIY patio, building a foundation, or working on a professional construction project, accurately estimating concrete requirements is essential. Our concrete calculator helps you determine exactly how much material you need, saving time, money, and reducing waste.
What is a Concrete Calculator?
A concrete calculator is a specialized tool that calculates the volume of concrete needed for various construction elements like slabs, columns, walls, and footings. It converts dimensions into cubic yards or meters—the standard measurement for concrete ordering—and provides estimates for the required materials including cement, sand, and gravel.
How to Use Our Concrete Calculator
Our calculator offers four specialized tools for different concrete applications:
- Slab Calculator: For flat surfaces like floors, driveways, and patios
- Column Calculator: For round or square support columns
- Wall Calculator: For concrete walls and barriers
- Footing Calculator: For foundation footings and bases
Step-by-Step Calculation Process
Follow these simple steps:
- Select the appropriate tab for your project type
- Enter dimensions in your preferred units (feet, inches, yards, meters, or centimeters)
- Click "Calculate" to get precise volume measurements
- Review the material estimates for your concrete mix
Example Calculation: Concrete Slab
Let's say you need to pour a concrete slab for a patio that measures 12 feet long, 10 feet wide, and 4 inches thick:
- Length: 12 feet
- Width: 10 feet
- Thickness: 4 inches
The calculator would determine you need approximately 1.48 cubic yards of concrete (including a 10% waste factor), which translates to about 9 bags of cement, 0.74 cubic yards of sand, and 1.11 cubic yards of gravel for a standard 1:2:3 mix.
Key Terms and Formulas
Understanding these basic concepts will help you make accurate calculations:
Volume Formulas:
- Slab/Wall/Footing Volume: Length × Width × Height (all in same units)
- Column Volume: π × Radius² × Height (for cylindrical columns)
- Unit Conversion: 1 cubic yard = 27 cubic feet
Standard Concrete Mix Ratio (1:2:3):
- 1 part Portland cement
- 2 parts sand
- 3 parts gravel or crushed stone
- Water: Approximately 0.5 parts (adjust for desired consistency)
About This Tool
Our concrete calculator uses precise mathematical formulas to convert your project dimensions into accurate volume measurements. It automatically handles unit conversions and applies industry-standard calculations to determine material requirements. The tool includes a 10% waste factor to account for spillage, over-excavation, and other common issues that can lead to material shortages.
The calculator is designed for both DIY enthusiasts and construction professionals, providing reliable estimates for projects of any scale. All calculations are performed locally in your browser, ensuring your data remains private and secure.
Concrete Mix Guide
Standard Concrete Mix Ratios
| Mix Type | Cement | Sand | Gravel | Strength (PSI) |
|---|---|---|---|---|
| 1:2:3 Mix | 1 part | 2 parts | 3 parts | 3,000 - 3,500 |
| 1:1.5:3 Mix | 1 part | 1.5 parts | 3 parts | 4,000 - 4,500 |
| 1:1:2 Mix | 1 part | 1 part | 2 parts | 5,000 - 5,500 |
Concrete Bag Estimator
| Bag Size | Cubic Feet per Bag | Bags per Cubic Yard |
|---|---|---|
| 40 lb | 0.30 | 90 |
| 60 lb | 0.45 | 60 |
| 80 lb | 0.60 | 45 |
Note: These estimates are for general purpose concrete. Specialty mixes may vary.
Frequently Asked Questions
Concrete Construction Tips
Planning Your Concrete Project
- Always order 5-10% more concrete than your calculated volume to account for spillage and uneven ground
- Consider the weather - avoid pouring concrete in extreme heat or freezing temperatures
- Prepare the subgrade properly by compacting the soil and adding gravel if needed
- Use forms that are strong enough to hold the weight of wet concrete without bending
- Plan for control joints in slabs to control cracking (typically every 10 feet)
Pouring and Finishing Concrete
- Work quickly once the concrete is poured - you typically have about 60-90 minutes of working time
- Use a screed to level the concrete, then float it to smooth the surface
- For a non-slip finish, broom the surface when it's partially set
- Keep the concrete moist for at least 7 days to ensure proper curing
- Avoid heavy loads on new concrete for at least 7 days (full strength takes 28 days)
Safety Precautions
Always wear proper safety gear when working with concrete, including gloves, eye protection, and waterproof boots. Wet concrete is caustic and can cause skin burns. Avoid breathing concrete dust, and work in well-ventilated areas when mixing dry cement.