🏗️ Free Concrete Calculator
Calculate concrete volume for slabs, columns, and tubes.
What is this tool?
Our free concrete calculator estimates the volume of concrete needed for slabs, columns, and tubes. Perfect for DIY projects, construction planning, and material estimation.
How it works
Calculates volume: Slab = L×W×H, Column = πr²×H, Tube = πr²×H. Converts cubic feet to cubic yards (÷27) and estimates 80lb bags needed (1 bag ≈ 0.6 cu ft).
How to use
- Select shape (Slab, Column, or Tube).
- Enter dimensions in feet and inches.
- Set quantity for multiple identical pours.
- Click Calculate for volume and bag count.
Reference Table
| Slab Size | 4" Thick | 6" Thick |
|---|---|---|
| 10×10 ft | 1.23 yd³ | 1.85 yd³ |
| 20×20 ft | 4.94 yd³ | 7.41 yd³ |
Frequently Asked Questions
How many bags do I need?
One 80lb bag of concrete mix yields approximately 0.6 cubic feet. Always order 5-10% extra for waste.
Should I order by bag or ready-mix?
For projects under 2 yards, bags are more practical. For larger projects, ready-mix delivery is more economical.
Tips & Advice
Always add 5-10% extra for waste and spillage. Proper curing (keeping concrete moist for 7 days) ensures maximum strength.