Concrete Footing Calculator
Calculate the total cubic yards or cubic meters of concrete needed for post footings based on count, diameter, and depth.
Concrete Needed
Concrete footings (or piers) support posts for decks, fences, pergolas, and other structures.
Volume per Footing = π × (Diameter/2)² × Depth
Total Volume = Volume per Footing × Number of Posts
Common footing sizes:
- Fence posts: 8"–10" diameter, 24"–36" deep
- Deck posts: 12"–16" diameter, 36"–48" deep
- Pergola posts: 12"–14" diameter, 30"–42" deep
- Mailbox posts: 8"–10" diameter, 18"–24" deep
Depth guidelines:
- Must extend below the frost line in your area
- Typical frost depths: 12"–48"+ depending on climate
- Bottom of footing should rest on undisturbed soil
Pre-mixed concrete bags:
- 40 lb bag = ~0.011 cubic yards (0.3 cu ft)
- 60 lb bag = ~0.017 cubic yards (0.45 cu ft)
- 80 lb bag = ~0.022 cubic yards (0.6 cu ft)
Add 10% extra for waste and uneven holes.