The Tank Surface Area Calculator calculates the outside surface area of storage tanks and vessels by adding the shell and the ends (heads).
Tank Surface Area Calculator
Surface area of vertical and horizontal cylindrical tanks (flat, hemispherical or 2:1 ellipsoidal heads) and rectangular tanks.
The cylindrical shell is π × D × L. The ends depend on the tank: flat circles (πD² ÷ 4 each), hemispheres (πD² for both), or 2:1 ellipsoidal heads (about 1.084 × D² each). Choose a vertical cylinder (open or closed top), a horizontal tank with flat, hemispherical or 2:1 ellipsoidal heads, or a rectangular tank.
Formula
| Tank type | Total surface area |
|---|---|
| Vertical cylinder | A = πDH + n × πD² ÷ 4 (n = 2 closed, 1 open top) |
| Horizontal, flat ends | A = πDL + 2 × πD² ÷ 4 |
| Hemispherical heads | A = πDL + πD² |
| 2:1 ellipsoidal heads | A = πDL + 2 × head area (≈ 1.084D² per head) |
| Rectangular | A = LW(1 + top) + 2H(L + W) |
Where:
- D = tank diameter; H = height of a vertical tank
- L = straight shell length (not including the heads)
- W = width of a rectangular tank; top = 1 if closed, 0 if open
The 2:1 ellipsoidal head area comes from the exact oblate-spheroid formula, πa²(1 + ((1 − e²) ÷ e) × atanh e) with e = √0.75.
How the Calculation Works
Step 1: Calculate the shell (side) area: circumference × straight length.
Step 2: Calculate the area of the ends for the chosen head type.
Step 3: Add the shell and ends. For open-top tanks the top is left out.
Variables Explained
| Variable | Meaning | Unit |
|---|---|---|
| D | Outside diameter | ft, m, in |
| H / L | Shell height or straight length | ft, m, in |
| A | Surface area | ft², m² |
Example Calculation
Vertical tank, closed top
Given: D = 10 ft, H = 12 ft
Shell: 3.14159 × 10 × 12 ≈ 376.99 ft²; top and bottom: 2 × 78.54 = 157.08 ft²
Result: A ≈ 534.07 ft²
Horizontal tank with 2:1 ellipsoidal heads
Given: D = 6 ft, straight shell length = 20 ft
Shell: 3.14159 × 6 × 20 ≈ 376.99 ft²; each head ≈ 1.084 × 36 ≈ 39.02 ft²
Result: A ≈ 376.99 + 2 × 39.02 = 455.04 ft²
Rectangular tank
Given: 8 × 4 × 4 ft, closed
Result: A = 2 × 32 + 2 × 4 × (8 + 4) = 160 ft²
Common Area Conversion Table
| Unit | Equivalent |
|---|---|
| 1 m² | 10.7639 ft² |
| 1 ft² | 0.0929 m² |
| 1 yd² | 9 ft² |
Engineering Assumptions
- Areas are for the tank’s outside geometric surface. Nozzles, manways, ladders, stiffeners and supports are not included.
- Wall thickness is ignored; for the inside surface, use inside dimensions.
- Head shapes are treated as ideal. Real torispherical (flanged and dished) heads differ from ellipsoidal heads.
Formula Variations
Wetted area
If you need only the area in contact with liquid (for relief-valve sizing or heat transfer), use the Wetted Surface Area Calculator, which accounts for the liquid level.
Material Estimation Notes
For coatings, divide the surface area by the product’s stated coverage per coat multiply by the number of coats, and add a loss allowance that suits your application method and site conditions.
Frequently Asked Questions
How do you calculate the surface area of a cylindrical tank?
Add the shell (πDH) and the two ends (2 × πD² ÷ 4 for flat ends).
What is the surface area of a 2:1 ellipsoidal head?
About 1.084 × D² per head, where D is the tank diameter.
How do you find the surface area of a horizontal tank?
Shell area πDL plus the area of both heads for the head type you have.
How do you calculate the surface area of an open-top tank?
Include the shell and the bottom only: πDH + πD² ÷ 4. Select “Open top” in the calculator.
How do I calculate paint for a tank?
Use the total surface area, divide by the paint’s coverage per coat, and multiply by the number of coats.