About this tool
Tank Volume Calculator is a free, in-browser tool that computes the capacity of a vertical cylinder, horizontal cylinder or rectangular tank in US gallons, liters and cubic feet, and the partial volume at a given fill depth. Enter dimensions in feet, inches, meters or centimeters; everything is computed locally as you type and nothing is uploaded.
All dimensions are converted to meters (ft × 0.3048, in × 0.0254, cm × 0.01) and the volume is found in cubic meters, then reported as gallons (× 264.172), liters (× 1000) and cubic feet (× 35.3147). A vertical cylinder is π·r²·height; a horizontal cylinder is π·r²·length; a box is length × width × height. For a partial fill, a vertical cylinder or box fills linearly with depth. A horizontal cylinder uses the circular-segment area A = r²·acos((r − d) ÷ r) − (r − d)·√(2·r·d − d²) at fill depth d measured up from the bottom of the cross-section, so partial volume = A × length.
Use it to gauge a water, fuel or oil tank: leave fill depth blank for full capacity, or enter how deep the liquid stands to read the current volume and percent full.