Water Tank Volume Calculator
Calculate water tank capacity and partial fill volume for vertical, horizontal, and rectangular tanks. Features exact circular segment dipstick math.
Multiplying rectangular length, width, and height.
Current volume based on liquid height.
Calculates total capacity and current held volume for vertical cylinders, horizontal cylinders, and rectangular tanks. For horizontal tanks, it uses circular segment trigonometry to convert dipstick fill depth into gallons and percentage full.
Water Tank Volume Calculator Formula & Sizing Rules
| Variable | Definition | Standard Units |
|---|---|---|
| r | Tank radius (half of tank diameter) | inches or feet |
| L | Tank length along the horizontal axis | inches or feet |
| h | Liquid depth measured from bottom with dipstick | inches or feet |
Why Horizontal Tanks are Non-Linear
In a vertical tank, liquid volume is directly proportional to fill height: half height equals half full. In a horizontal cylinder, however, the tank is narrow at the bottom, widest at the middle, and narrow again at the top. A dipstick reading of 25% height holds significantly less than 25% of total capacity.
Common Project Sizing Mistakes
- Assuming 50% dipstick depth means 50% full on an unlevel horizontal tank
- Ignoring head shape on large industrial tanks with dished or hemispherical ends
Frequently Asked Questions
How do you calculate how many gallons are in a horizontal tank?▼
How much does water weigh per gallon?▼
How do you find the capacity of a vertical cylinder tank?▼
What is tank ullage in liquid storage?▼
Authoritative Sources & Reference Standards
- Guide for the Use of the International System of Units (SI), NIST Special Publication 811 — National Institute of Standards and Technology (NIST). Verified 2026-10-01.
Official SI unit definitions, conversion factors (Appendix B), and precision standards for cubic meters, liters, and US customary units.
- NIST Handbook 44: Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices — NIST Office of Weights and Measures. Verified 2026-10-01.
Legal commercial measurement standards for liquids, tanks, and bulk volumetric containers in the United States.