Concrete Calculator & Estimator
Accurately calculate concrete volume in cubic yards, meters, and estimate premix bags.
💡 How to Use This Calculator
- Select the **structure shape** (Slab, Hole, Tube, Curb, or Stairs) from the tabs.
- Refer to the **diagram** to identify dimensions (Length, Width, Rise, Run, etc.).
- Enter your dimensions and select the correct unit (feet, inches, cm, meters, or yards).
- Click **"Calculate Volume"** to see results in cubic yards (yd³) and cubic meters (m³).
The Ultimate Guide to Calculating Concrete
Whether you are a DIY enthusiast building a backyard patio or a contractor pouring a foundation, accurate estimation is key. Ordering too little concrete creates expensive delays (and cold joints), while ordering too much is wasted money.
1. Understanding Concrete Volumes
Concrete is sold by volume, not weight.
- Cubic Yards (yd³): The standard unit in the United States. One cubic yard is equal to 27 cubic feet.
- Cubic Meters (m³): The standard unit in most other countries. One cubic meter is approx 1.3 cubic yards.
2. Formulas Used
Rectangular Slabs:Volume = Length × Width × Thickness
Circular Columns:Volume = π × (Radius)² × Height
3. Premix Bags Required
If buying premix bags like Quikrete or Sakrete:
- 60lb Bag: Yields ~0.45 cubic feet. (Requires ~60 bags per cubic yard)
- 80lb Bag: Yields ~0.60 cubic feet. (Requires ~45 bags per cubic yard)
Frequently Asked Questions
How many bags of concrete do I need for 1 cubic yard?
For standard premix concrete, you need approximately 45 bags of 80lb mix or 60 bags of 60lb mix.
How do I calculate concrete for a slab?
Multiply Length x Width x Thickness to get volume. If using feet, divide by 27 to get cubic yards.
How much does a yard of concrete weigh?
A cubic yard of standard concrete weighs approximately 4,000 lbs (1,800 kg).
Should I add extra concrete?
Yes, order 5% to 10% extra for spillage and uneven subgrades.