A walkthrough, end to end.
- 1
Pick a shape: slab, footing, or column.
- 2
Enter dimensions in feet and inches (or metric).
- 3
See cubic yards, cubic meters, and bags needed for 60 lb and 80 lb pre-mix.
Concrete volume
Slab/footing: V = L × W × thickness. Column (cylinder): V = π r² × height. 1 cu yd ≈ 60 bags of 60 lb or 45 bags of 80 lb pre-mix.
What you can do with this.
Slab pour
Patio, shed, or garage slab — typical 4-inch thickness.
Footings
Frost-line trenches under foundations and posts.
Fence post
Sonotube cylinders around 4×4 posts.
Steps
Sum each step's slab volume.
Driveway extension
Common 4–6 inch thickness for residential drives.
Walkway
3.5-inch slab for foot traffic.
Mailbox base
Small post-hole pour.
Concrete 2026 — what's current
Standard estimating; calculator wins for instant bag count.
Frequently asked.
60 lb bag yields ~0.45 cu ft, 80 lb bag ~0.6 cu ft. 1 cu yd ≈ 60 of 60 lb or 45 of 80 lb.
Yes — buy 5–10% extra for spillage and irregular forms.
No. All math runs in your browser.
For ≥1 cu yd, a ready-mix truck is usually cheaper than buying bags.