An aquarium volume calculator for a rectangular tank converts inner length, width, and water height to litres, US gallons, and UK gallons. Substrate litres use the footprint times gravel depth. Glass thickness is not subtracted; measure inside.
A rectangular 90 × 45 × 45 cm tank is 182.3 L (48.2 US gal). Water weight is about 182 kg plus glass and stand.
Water volume
182.3 L
Results can be wrong. This calculator is unofficial. Figures can be incomplete, rounded, or not updated. Use them at your own risk and check a tape, datasheet, ball band, or official chart before cutting, mixing, buying, or publishing. Measure inside the glass. Hexagon length is point-to-point; a flat-to-flat measure will mis-size the tank. Bowfront extra is an ellipse, not the real curve. Limits of liability are in the terms of service.
Inner. Outer millimetres include glass thickness and overstate water.
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Publisher notes · reviewed 29 October 2026
A 90×45×45 cm rectangle is 182.3 L. US gallons divide by 3.785. Measure inside; glass thickness is not subtracted. Substrate is footprint × depth.
This is geometry, not a livestock rule. Filter flow and species care are separate.
90×45×45 cm
182.3 L, about 48.2 US gal, 40.1 UK gal.
