You will find that aquarium tanks are always described by their internal volume.
Tank size conversion chart
All gallons are US gallons which are smaller than UK gallons.
| Aquarium Tank (US) | Width | Depth | Height |
| 2.5 Gallons | 12 in | 6 in | 8 in |
| 9.4 Litres | 30.48 cm | 15.24 cm | 20.32 cm |
| 5 Gallons | 16 in | 8 in | 10 in |
| 18.95 Litres | 40.64 cm | 45.72 cm | 25.4 cm |
| 10 Gallons | 20 in | 10 in | 12 in |
| 37.9 Litres | 50.8 cm | 25.4 cm | 30.48 cm |
| 15 Gallons | 20 in | 12 in | 12 in |
| 56.85 Litres | 50.8 cm | 30.48 cm | 30.48 cm |
| 15 Gallons High | 20 in | 10 in | 18 in |
| 56.85 Litres High | 50.8 cm | 25.4 cm | 45.72 cm |
| 20 Gallons High | 24 in | 12 in | 16 in |
| 75.8 Litres High | 60.96 cm | 30.48 cm | 40.64 cm |
| 20 Gallons Long | 30 in | 12 in | 12 in |
| 75.8 Litres Long | 76.2 cm | 30.48 cm | 30.48 cm |
| 25 Gallons | 24 in | 12 in | 20 in |
| 94.75 Litres | 60.96 cm | 30.48 cm | 50.8 cm |
| 29 Gallons | 30 in | 12 in | 18 in |
| 109.91 Litres | 76.2 cm | 30.48 cm | 45.72 cm |
| 30 Gallons | 36 in | 18 in | 12 in |
| 113.7 Liters | 91.44 cm | 45.72 cm | 30.48 cm |
| 40 Gallons | 48 in | 12 in | 16 in |
| 151.6 Litres | 121.92 cm | 30.48 cm | 40.64 cm |
| 40 Gallons | 36 in | 18 in | 16 in |
| 151.6 Liters | 91.44 cm | 45.72 cm | 40.64 cm |
| 50 Gallons | 36 in | 18 in | 19 in |
| 189.5 Litres | 91.44 cm | 45.72 cm | 48.26 cm |
| 55 Gallons | 48 in | 13 in | 21 in |
| 208.45 Litres | 121.92 cm | 33.02 cm | 53.34 cm |
| 65 Gallons | 36 in | 18 in | 24 in |
| 246.35 Litres | 91.44 cm | 45.72 cm | 60.96 cm |
| 75 Gallons | 48 in | 18 in | 21 in |
| 284.25 Litres | 121.92 cm | 45.72 cm | 53.34 cm |
| 90 Gallons | 48 in | 18 in | 24 in |
| 341.1 Litres | 121.92 cm | 45.72 cm | 60.96 cm |
| 125 Gallons | 72 in | 18 in | 21 in |
| 473.75 Litres | 182.88 cm | 45.72 cm | 53.34 cm |
| 150 Gallons | 72 in | 18 in | 28 in |
| 568.5 Litres | 182.88 cm | 45.72 cm | 71.12 cm |
| 180 Gallons | 72 in | 24 in | 25 in |
| 682.2 Litres | 182.88 cm | 60.96 cm | 63.5 cm |