Concrete Calculator
Calculate how much concrete you need by area and depth — cubic yards, estimated tons and bags. Slabs and footings — 4 in is standard for a residential slab. Bag count is 80 lb premix.
Slabs and footings — 4 in is standard for a residential slab. Bag count is 80 lb premix.
Concrete at 4 in deep · density ≈ 1.96 tons/yd³ · 80 lb bags.
| Area ft² | Cubic yards | Tons (est.) | 80 lb bags |
|---|---|---|---|
| 50 ft² | 0.62 | 1.21 | 28 |
| 100 ft² | 1.23 | 2.42 | 56 |
| 200 ft² | 2.47 | 4.83 | 112 |
| 300 ft² | 3.70 | 7.25 | 167 |
| 500 ft² | 6.17 | 12.1 | 278 |
| 750 ft² | 9.26 | 18.1 | 417 |
| 1,000 ft² | 12.3 | 24.2 | 556 |
Per 100 ft² by depth
| Depth | Cubic yards | Tons | Bags |
|---|---|---|---|
| 1 in | 0.31 | 0.60 | 14 |
| 2 in | 0.62 | 1.21 | 28 |
| 3 in | 0.93 | 1.81 | 42 |
| 4 in | 1.23 | 2.42 | 56 |
| 6 in | 1.85 | 3.63 | 84 |
Tonnage is an estimate from loose, dry bulk density; damp or compacted material weighs more. Order ~5–10% extra for settling.
To find the right quantity of concrete, multiply the area (length × width) by the depth and divide by 27 to convert cubic feet to cubic yards. This calculator does that automatically and also shows estimated tons and the number of bags you would need if buying in retail bags.
Bulk concrete is usually sold by the cubic yard for delivery. The table above covers the most common project sizes at a 4 inches depth — if your depth differs, enter your exact dimensions in the main calculator. Always order about 5–10% extra to allow for settling, waste and uneven ground.
Frequently asked questions
How many cubic yards of concrete do I need?
Multiply the area in square feet by the depth in feet, then divide by 27. For example, a 200 ft² bed at 4 in deep = 200 × 0.3333 ÷ 27 = 2.47 cubic yards.
How much does a cubic yard of concrete weigh?
Concrete weighs approximately 1.96 tons (3,915 lb) per cubic yard as loose, dry material. Damp or compacted material can weigh more — treat the tonnage as a planning estimate and confirm with your supplier.
How many bags of concrete are in a cubic yard?
Concrete bags are typically 80 lb bags. One cubic yard (27 cubic feet) takes roughly 45 bags. For any project bigger than a small area, bulk delivery by the yard is usually more economical.