// excavation & footing volume instrument
Hole volume calculator
Enter your hole's top and bottom diameter and depth to get excavation volume — and optionally subtract a post or pier to see how much concrete you'll actually need to fill around it.
Hole dimensions
Same top and bottom diameter gives a straight cylindrical hole; different values give a tapered (frustum) hole, common with auger or bell-bottom digs.
Post or pier (optional)
Estimate
Fill volume (all holes)
0.00 yd³
0 cu ft total
Volume per hole
0 cu ft
80 lb bags needed
0
Tapered holes use the frustum formula V = (πh/3)(R₁² + R₁R₂ + R₂²). Post volume is subtracted per hole before totals. Bag count uses a typical 80 lb bag yield of ~0.60 cu ft.