5 Gallon Aquarium dimensions
The standard small glass tank is sold as a 5.5 gallon, not a 5 — Aqueon's version is 16³⁄₁₆ × 8⅜ × 10½ in. Most “5 gallon” kits are this box or something close to it.
Measuring your own tank? The rectangular tank volume calculator works out gallons at any water depth.
| Spec | Value |
|---|---|
| Length | 16³⁄₁₆ in |
| Width | 8⅜ in |
| Height | 10½ in |
| Geometric capacity | 6.2 gal |
| Nominal rating | 5.5 gal |
| Liquid weight (brim-full) | 51 lb of water |
| Empty tank weight (manufacturer) | 7 lb |
| Full weight (manufacturer) | 62 lb |
Nominal rating versus real geometry
Rated 5.5 gal. Computed from the dimensions in the table above: 6.2 gal. The geometry comes out 0.7 gallons over the label — 12 %. Exterior dimensions include the glass and trim, so the real water volume is lower than this brim-full figure, usually by a few percent.
What this weighs on your floor
| Water, brim full | 51 lb |
| Plus glass, substrate, rock and stand (≈ 25 % allowance) | ≈ 64 lb gross |
| Footprint | 16³⁄₁₆ in × 8⅜ in = 0.9 ft² |
| Load over its own footprint | ≈ 68 lb/ft² |
| IRC design live load, habitable room (not a bedroom) | 40 lb/ft² |
| IRC design live load, sleeping room | 30 lb/ft² |
That is roughly 1.7× the 40 lb/ft² design live load in IRC Table R301.5, over the tank's own footprint — what that does and does not mean is set out in the aquarium reference.
What is the same for every tank of this kind (floor loading, from rated size to actual water volume, what governs an aquarium's rated size) is set out once on the sizes hub, in the aquarium reference and the common questions for every tank.
Dimension drawing
FAQ
What are the dimensions of a 5 gallon aquarium?
Aqueon lists its Standard 5.5 (SKU 100110005) at 16³⁄₁₆ × 8⅜ × 10½ in (length × width × height, exterior). Other makers' tanks with the same rating can differ by an inch or so — check your tank's label or spec sheet.
How much does a full 5.5 gallon aquarium weigh?
About 51 lb of water filled to the brim, before the glass, substrate, rock and stand. With a typical allowance for those, plan for roughly 64 lb.
How many gallons does a 5.5 gallon aquarium really hold?
Brim-full, the exterior dimensions give 6.2 gal. In use, with an inch of air gap and a substrate bed, expect several gallons less — enter your own water depth in the rectangular tank volume calculator.
Is a 5 gallon tank the same as a 5.5 gallon?
In practice yes — the standard rectangular glass tank in this class is rated 5.5 gallons. Kits sold as “5 gallon” vary in shape; measure yours and use the rectangular calculator if it is not this box.
Sources and standards
- 2026 Aqueon Product Catalog — Critical dimensions for all aquariums (p. 57)Aqueon / Central Garden & Pet (manufacturer)https://www.aqueon.com/-/media/project/oneweb/aqueon/files/us/product-catalog/2026-aqueon-catalog.pdf“5½ 16³⁄16 x 8³⁄8 x 10½ 7 62” — exterior L × W × H in inches, empty and full weight in lb. Aqueon's product page rounds it to 16.25 × 8.4 × 10.5 in.
- Handbook 44, Appendix C — General Tables of Units of MeasurementNational Institute of Standards and Technology, U.S. Department of Commercehttps://www.nist.gov/document/2026-nist-handbook-44-appendix-c
- International Residential Code, Table R301.5 — Minimum uniformly distributed live loadsInternational Code Council (free read-only access at codes.iccsafe.org)https://codes.iccsafe.org/s/IRC2021P2/chapter-3-building-planning/IRC2021P2-Pt03-Ch03-SecR301.5
- Methodology — the partial-fill formulas and liquid densities used on this sitetankvolumecalc.comhttps://tankvolumecalc.com/methodology/
Every linked source above was retrieved and checked on 2026-11-01.