Hollow Cylinder Volume Calculator
Calculate the volume, wall thickness, inner/outer radius and diameter, surface area, and mass of a hollow cylinder or cylindrical pipe with step-by-step math.
What Is a Hollow Cylinder?
A hollow cylinder (also known as a cylindrical shell, circular tube, or pipe) is a three-dimensional geometric solid bounded by two concentric cylindrical surfaces sharing the same rotational axis and height. It consists of an outer cylinder of radius $R$ (or outer diameter $D$) from which a coaxial inner cylindrical core of radius $r$ (or inner diameter $d$) has been removed.
Hollow Cylinder Formulas
The geometry of a cylindrical shell involves several key formulas derived from basic cylinder dimensions:
1. Wall Thickness ($t$)
The wall thickness is the radial difference between the outer and inner radius:
$$t = R - r = \frac{D - d}{2}$$
2. Annular Cross-Sectional Area ($A_{cs}$)
The cross-sectional area perpendicular to the length of the cylinder is an annulus (a ring):
$$A_{cs} = \pi (R^2 - r^2) = \pi (R - r)(R + r) = \pi t (2r + t)$$
3. Hollow Cylinder (Shell) Volume ($V_H$)
The material volume of the solid shell is the cross-sectional area multiplied by the cylinder length or height $h$:
$$V_H = \pi (R^2 - r^2) h = \pi (t^2 + 2tr) h$$
Alternatively, this equals the difference between the total outer cylinder volume and the inner void volume:
$$V_H = V_{outer} - V_{inner} = \pi R^2 h - \pi r^2 h$$
4. Surface Area Formulas
- Outer Lateral Area: $A_{lat,out} = 2\pi R h$
- Inner Lateral Area: $A_{lat,in} = 2\pi r h$
- Total Lateral Area: $A_{lat} = 2\pi (R + r) h$
- Two End Rings (Caps): $A_{caps} = 2\pi (R^2 - r^2)$
- Total Surface Area: $A_{tot} = 2\pi (R + r) h + 2\pi (R^2 - r^2)$
5. Mass and Weight Calculation
The mass $m$ of the hollow cylinder depends on the material density $\rho$ and the solid shell volume $V_H$:
$$m = \rho \times V_H$$
Common Material Densities
| Material | Density (g/cm³) | Density (kg/m³) |
|---|---|---|
| Structural Steel | 7.85 | 7,850 |
| Aluminum | 2.70 | 2,700 |
| Copper | 8.96 | 8,960 |
| Brass | 8.50 | 8,500 |
| PVC Plastic | 1.38 | 1,380 |
| Concrete | 2.40 | 2,400 |
For other 3D geometry calculations, check out our Cylinder Calculator, Pipe Volume Calculator, and Cross-Sectional Area Calculator.
Frequently Asked Questions
How do you calculate the volume of a hollow cylinder?
To find the material volume of a hollow cylinder, subtract the inner cavity cylinder volume from the outer cylinder volume: $V_H = \pi(R^2 - r^2)h$, where $R$ is the outer radius, $r$ is the inner radius, and $h$ is the height or length.
What is the difference between inner volume and hollow cylinder volume?
The inner volume $V_{in} = \pi r^2 h$ measures the internal fluid capacity or empty cavity inside the tube. The hollow cylinder volume $V_H = \pi(R^2 - r^2)h$ measures the solid material making up the pipe walls.
What is the volume of a hollow cylinder with D = 10 cm, d = 6 cm, and height = 20 cm?
First find radii: $R = 5\text{ cm}$ and $r = 3\text{ cm}$. Calculate the cross-sectional ring area: $A_{cs} = \pi(5^2 - 3^2) = \pi(25 - 9) = 16\pi \approx 50.265\text{ cm}^2$. Multiply by height $h = 20\text{ cm}$: $V_H = 50.265 \times 20 \approx 1,005.31\text{ cm}^3$.
Does the formula change if the inner cylinder is off-center (eccentric)?
No. As long as the inner hole is parallel to the outer cylinder throughout the entire height $h$, Cavalieri's principle guarantees that the solid material volume remains exactly $V_H = \pi(R^2 - r^2)h$.
How do I find wall thickness from outer diameter and inner diameter?
Subtract inner diameter $d$ from outer diameter $D$ and divide by 2: $t = (D - d)/2$.