Accurate tank volume calculations are essential for environmental compliance, including SPCC plans, Tier II chemical inventory reporting, and EPA tank registration. Use our free calculator to determine the total capacity and current fill volume of horizontal cylindrical, vertical cylindrical, and rectangular tanks. Results are provided in cubic feet, US gallons, and petroleum barrels.
Conversions: 1 ft³ = 7.48052 US gallons | 1 barrel = 42 US gallons | SPCC threshold: 1,320 gallons aggregate aboveground oil storage
The total volume of a horizontal cylinder is π × r² × L, where r is the radius (half the diameter) and L is the total length. For the partial fill volume at a given liquid height h, the formula uses the circular segment area multiplied by the length: V = L × [ r² × arccos((r−h)/r) − (r−h) × √(2rh − h²) ]. This accounts for the curved cross-section of the cylinder.
The total volume is π × r² × H, where r is the radius and H is the total height. For partial fill, simply replace H with the liquid height h: Fill Volume = π × r² × h. Vertical cylinders have a linear relationship between fill height and volume, making them easier to gauge than horizontal cylinders.
Total volume is Length × Width × Height. For partial fill, replace the height with the liquid level: Fill Volume = Length × Width × fill height. Like vertical cylinders, rectangular tanks have a linear fill-to-volume relationship.
One cubic foot equals 7.48052 US gallons. To convert cubic feet to gallons, multiply the volume in cubic feet by 7.48052. For example, a tank with a volume of 100 cubic feet holds 748.05 gallons.
One petroleum barrel equals 42 US gallons. This is the standard barrel measurement used in the oil industry and in environmental regulations. One cubic foot equals approximately 0.1781 barrels.
This calculator asks for the diameter (the full width across the tank). The radius is calculated automatically as half the diameter. If you only know the circumference, divide it by π (3.14159) to get the diameter.
Divide the number of inches by 12 and add to the whole feet. For example: 6 feet 8 inches = 6 + (8/12) = 6.667 feet. Common conversions: 3 inches = 0.25 ft, 6 inches = 0.5 ft, 9 inches = 0.75 ft.
Accurate tank volume calculations are required for multiple environmental regulations:
A Spill Prevention, Control, and Countermeasure (SPCC) plan is required under EPA 40 CFR 112 for facilities that store oil and could reasonably be expected to discharge into U.S. navigable waters. The plan must include a facility diagram with tank locations, capacities, and secondary containment details. Accurate tank volume calculations are the foundation of SPCC compliance.
This calculator uses the dimensions you enter to calculate volume. For the most accurate results, enter the internal dimensions of the tank (inside diameter, inside length). Tank wall thickness can reduce the actual storage volume by 1–5% depending on the tank size and construction material.
Environmental regulations require accurate tracking of tank inventories, inspections, and reporting. EHS software streamlines these requirements:
Tank Inventory Management - Maintain a centralized database of all storage tanks at your facility, including tank type, dimensions, capacity, contents, and installation dates. Generate reports for regulatory submissions and audits.
SPCC Plan Documentation - Store and manage your SPCC plan digitally, including facility diagrams, tank specifications, secondary containment details, and inspection schedules. Track plan amendments and ensure all locations have current documentation.
Inspection Scheduling and Tracking - Schedule and document regular tank inspections, including visual checks, integrity testing, and secondary containment inspections. Assign corrective actions for any deficiencies found.
Tier II Reporting - Track chemical inventories across all storage tanks to streamline annual Tier II reporting under EPCRA. Software calculates maximum and average daily amounts automatically from your inventory records.
Spill Incident Management - Report, investigate, and track spill incidents from initial notification through corrective actions and regulatory reporting. Document root causes and prevent recurrence.
Compliance Obligation Tracking - Track regulatory deadlines for tank inspections, registrations, SPCC reviews, and reporting requirements. Automated reminders ensure nothing falls through the cracks.
Click on the "CONTACT US FOR HELP!" link below to see these benefits in action with a free trial of Ecesis EHS Software.
Please call us at (720) 547-5102 or complete the form below to learn more about how Ecesis can help you manage tank compliance, SPCC plans, and environmental reporting.
If you need help with tank volume calculations or environmental compliance, please call us at (720) 547-5102.
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