Concrete Calculator - Calculate Yards, Cubic Feet & Bags Needed

How to Use the Concrete Calculator

1. Select the shape that matches your project — slab (rectangle/square), column (cylinder), or footing
2. Enter dimensions — length, width, and depth (or diameter and height for columns) in feet/inches or meters
3. Choose your measurement units — switch between imperial (feet/inches) and metric (meters/cm) freely
4. Select bag size — choose from 40lb, 60lb, 80lb, or 90lb bags to get an exact bag count
5. Read the results — see cubic feet, cubic yards, estimated weight, and number of bags needed instantly

Perfect for contractors, DIYers, and construction pros. All calculations happen in your browser — nothing is uploaded.

Features

• Multiple shapes — slab, column, and footing modes cover the most common projects
• Unit conversion — work in feet/inches or meters/centimeters, whichever you prefer
• Bag calculator — shows exactly how many bags you need for 40lb, 60lb, 80lb, and 90lb mixes
• Total weight — estimated weight of concrete needed for transport planning
• Instant results — updates as you type without any page reloads
• Volume in multiple units — see results in cubic yards, cubic feet, and cubic meters simultaneously

Use Cases

• Pouring a patio slab — enter the length, width, and 4-inch depth to calculate exactly how many yards to order
• Setting fence posts — use the column mode with post diameter and depth to figure bags per post
• Foundation footings — calculate the volume for continuous footings under a new wall or extension
• Ordering ready-mix — get the cubic yardage to call in your ready-mix concrete order without over-ordering

FAQ

How much does a yard of concrete weigh?

A cubic yard of concrete weighs approximately 4,000 pounds (1.8 metric tons). This varies slightly by mix design but is the standard estimate used in construction.

Should I order extra concrete?

Yes — always order 5-10% more than calculated to account for spillage, uneven subgrades, and slight depth variations. The calculator doesn’t add waste automatically, so factor this in.

How many 80lb bags make a yard?

It takes approximately 45 bags of 80lb concrete mix to make one cubic yard. The calculator breaks this down automatically for each bag size.

Can I pour concrete in cold weather?

Concrete can be poured in temperatures as low as 25°F (-4°C) using accelerators and insulating blankets, but the ideal range is 50-70°F (10-21°C). Below 25°F, fresh concrete can freeze and lose strength permanently.