Tank Volume Calculator

Tank capacity is the internal geometric volume available for a liquid or bulk material. This calculator covers three common tank forms: rectangular boxes, vertical circular cylinders, and spheres. Enter internal dimensions in meters, and the result is displayed in cubic meters, liters, and US liquid gallons. A fill-level percentage can reduce the full geometric capacity to an intended operating volume. A rectangular tank uses length multiplied by width multiplied by height. A vertical cylindrical tank uses pi multiplied by radius squared and height. A sphere uses four thirds multiplied by pi and radius cubed. One cubic meter equals 1,000 liters and approximately 264.172 US gallons. The calculator performs these conversions after applying the selected fill percentage, so all three displayed values represent the same usable volume. Internal dimensions matter. Manufacturer specifications often give outside dimensions, but wall thickness, insulation, liners, internal coils, supports, and dished heads reduce actual storage space. If only outside dimensions are available, subtract the wall thickness from both sides of each relevant dimension before calculating. Real cylindrical vessels may have domed or conical ends rather than flat ends; those sections require separate formulas and should be added to the straight shell volume. The fill percentage is an operating allowance, not a model of a partly filled horizontal cylinder. For a vertical tank with a uniform cross section, fifty percent fill corresponds to half the height and half the volume. For a sphere, the relationship between liquid depth and volume is nonlinear, so the percentage field should represent the desired percentage of total capacity rather than a measured liquid height. Thermal expansion, foam, surge, vapor space, and regulatory freeboard can all require capacity to remain unused. Use the result for initial storage planning, pump sizing, treatment dosing, rainwater harvesting, and material estimates, but confirm critical designs against vessel drawings and applicable standards. Nominal tank labels may be rounded and can differ from exact geometric capacity. Also verify whether a project uses US gallons, imperial gallons, or liters, because gallon definitions differ. This calculator specifically reports US liquid gallons. With measured internal dimensions and a realistic fill allowance, it provides a quick, transparent estimate for construction, engineering, agricultural, and facility-management decisions.