Hole Volume Calculator
The hole volume calculator is a tool that helps you find the volume of a hole — whether it is cylindrical (round) or rectangular (box-shaped). It also includes a concrete volume calculator that tells you exactly how many bags of concrete you need to fill the hole.
Hole Volume Calculator — Cylinder
For a cylindrical hole, the calculator uses the following formula:
Volume = π × (diameter ÷ 2)² × depth
You only need to enter the diameter (or you can think of it as twice the radius) and the depth of the hole. Our round hole volume calculator supports both Imperial (inches) and Metric (centimeters) units and instantly converts the result into cubic inches, cubic feet, and cubic yards (Imperial) or cubic centimeters, liters, and cubic meters (Metric).
Hole Volume Calculator — Rectangular Prism
For a rectangular hole, the formula is even simpler:
Volume = width × length × depth
Enter the width, length, and depth of the hole and the calculator will give you the volume in all common units.
How to Calculate the Volume of a Hole
- Select the shape of your hole: Cylinder (round post holes, sonotube forms, pipe holes) or Rectangular Prism (square footings, trenches, box-shaped excavations).
- Choose your measurement system: Imperial (inches) or Metric (centimeters).
- Enter the required dimensions.
- Click Calculate to see the volume and concrete estimate.
The Concrete Volume Calculator for Holes
Once the hole volume is known, the calculator automatically estimates the amount of concrete needed to fill the hole. It uses a standard concrete density of 150 lb/ft³ (2,400 kg/m³) and shows you how many pre-mixed bags you need:
- Imperial: 40 lb, 60 lb, and 80 lb bags
- Metric: 20 kg, 25 kg, and 40 kg bags
You can also enter a price per bag and select your currency (including USD, Russian Ruble ₽, Euro, British Pound, and 16 other world currencies) to get an instant cost estimate.
Practical Examples
Example 1: Cylindrical post hole (Imperial)
- Diameter: 12 in, Depth: 36 in
- Volume = π × 6² × 36 ≈ 4,072 in³ ≈ 2.36 ft³ ≈ 0.087 yd³
- Concrete weight ≈ 354 lb → 6 bags × 60 lb
Example 2: Rectangular footing hole (Metric)
- Width: 40 cm, Length: 40 cm, Depth: 80 cm
- Volume = 40 × 40 × 80 = 128,000 cm³ = 128 L = 0.128 m³
- Concrete weight ≈ 307 kg → 13 bags × 25 kg
Tips
- Always add 10–15% extra concrete for spillage and irregular hole walls.
- For large projects, consider ordering ready-mix concrete by the cubic yard or cubic meter instead of bags.
- The diameter of a round hole equals twice the radius. If you only know the radius, multiply it by 2 before entering.
- For fence posts and deck footings, the most common hole size is 10–12 in (25–30 cm) diameter × 36 in (90 cm) deep.