About Tank Volume Calculator
Tank Volume Calculator is a free calculator and reference site for estimating the volume and capacity of common storage, utility, agricultural, commercial, and light industrial tanks.
What this site does
Enter a tank's dimensions and the calculator returns volume in US gallons, imperial gallons, litres, cubic feet, and cubic metres. For tanks that are only partially full, it calculates filled volume, empty volume, and percent full using the geometry for the selected tank shape.
The site also includes focused tools and guides for common real-world tank questions, including heating-oil tank charts, propane tank sizes, emergency water storage planning, septic tank sizing, and custom tank dip charts.
Who maintains this site
TankVolume.com is maintained as an independent calculator resource focused on tank volume, tank capacity, and tank measurement. The goal is to provide clear, practical calculators that show the formulas, assumptions, and limitations behind the numbers instead of hiding the math.
The site does not claim to be a manufacturer, code authority, engineering firm, propane supplier, septic designer, or certified tank calibration service. It is a calculation and reference resource for estimating tank capacity from dimensions.
How we approach accuracy
The calculator is built on a tested calculation engine, and the formulas, constants, and assumptions are documented on the methodology page. The formulas use standard geometric volume equations and consistent unit conversions, including US gallons, imperial gallons, litres, cubic feet, and cubic metres.
All results are calculated from ideal internal geometry. Real tanks may differ from calculated values because of wall thickness, fittings, rounded or dished ends, baffles, tilt, fill limits, usable-bottom volume, and manufacturing tolerances. For certified capacity, custody-transfer measurement, code compliance, installation, or safety decisions, use manufacturer data or a qualified professional.
What this site covers
TankVolume.com focuses on tank volume, capacity, and fill-level calculations for storage, utility, and liquid-holding tanks, including water tanks, fuel and oil tanks, propane tank capacity references, septic tanks, rainwater tanks, and general liquid-storage containers.
The calculators are designed for practical volume estimation, unit conversion, and capacity planning. They are not a substitute for manufacturer specifications, engineering drawings, safety guidance, regulatory compliance, or professional inspection.
This site does not cover aquarium or fish tank content. Aquarium volume is a separate topic with different measurement needs, equipment considerations, livestock concerns, filtration requirements, and use cases.
Looking for aquarium or fish tank volume instead? Use our dedicated aquarium volume calculator at AquariumVolume.com.
Corrections and updates
We welcome corrections, source suggestions, and reports of calculation or wording issues. If you notice a formula problem, unclear assumption, broken link, or tank type that should be handled differently, please use the contact page.
Last updated: June 2026.