5 Gallon Tank Dimensions

Not every 5 gallon is the same size

The “5 gallon” label is a class of tank, not an exact measurement. Here is what each source actually lists:

Checked 29 Sep 2026. Marineland's full weight (53 lb) is simply the label 5.5 gallons × 8.34 lb plus the empty tank. Aqueon's 62 lb is more than even the whole outside volume filled with water (58 lb); its chart notes that filled weights vary with substrate and decor. Neither includes the stand. The makers' "full" weights don't say how full; our set-up estimate further down uses the water left after 2 in of sand and a gap below the rim, plus the sand, so it can come out lower. Size your stand for the higher figure.

5 gallon vs the sizes around it

Every step in this range has its own footprint, so a stand, lid or light for one won't fit the next:

Aqueon size chart.

Going from a 5½ to a 10 gallon adds only 4 in of length but nearly doubles the water.

Why a “5 gallon” is sold as 5½

Neither Aqueon nor Marineland lists a standard 5.0 gallon glass tank. The rectangular tank sold as a 5 gallon is their 5½: 16 × 8 × 10 in nominal. Measured from the outside, Aqueon's comes to 6.2 gallons. Tanks sold as “5 gallon” kits are usually a different shape altogether. Aqueon's Mini Bow 5, for example, is 14¾ × 9½ × 15⅛ in: taller, shorter and curved at the front, so a 16 in lid or light won't fit it.

The bigger surprise is how little water is left. With 1/8 in glass, a 1 in gap below the rim and 2 in of sand, an Aqueon 5½ holds about 4.1 gallons, and about 5.3 with a bare bottom. At that size:

• A dosing mistake matters more. Measure conditioner and medication for the real water, not the label.
• A thinner sand bed helps. Each inch of sand takes up roughly half a gallon here; try 1 in in the calculator above.
• Heaters need care. Pick one sized for small tanks with a thermostat; an oversized heater can overshoot quickly in this little water.

How much water a 5 gallon really holds

Multiply the outside dimensions of an Aqueon 5 gallon and you get 6.2 gallons. You never get that much water, because of three things:

1. Glass. With about 1/8 in glass (an estimate; check your tank), the inside is roughly 15-15/16 × 8⅛ in.
2. The gap at the top. Most people keep the water about an inch below the rim.
3. Substrate. Two inches of sand takes up about 4 litres of space.

That leaves about 5.3 gallons with a bare bottom and 4.1 gallons with 2 in of sand. Use the real figure, not the label, when you dose medication or water conditioner.

Weight and stand

A set-up Aqueon 5 gallon comes to about 56 lb: 7 lb of glass, about 34 lb of water and about 15 lb of sand, before rock and the stand itself. That sits on 0.9 square feet.

• Set up, it weighs about 56 lb: light enough for a desk or shelf, as long as it's level and rated for that weight.
• Keep it out of direct sun and away from radiators. Small volumes warm up and cool down quickly.

General guidance, not structural advice.

Will a 5 gallon fit? Stand, doorway and floor

What stand does a 5 gallon need?

One with a top at least 16 3/16 × 8⅜ in, the Aqueon footprint, rated for at least 62 lb. That is the higher of the makers' full weights; our own set-up estimate is 56 lb. The whole bottom frame must sit on the stand, with nothing hanging over the edge.

Will a 5 gallon fit through a door?

Usually, yes. Carried end-first, the doorway only has to clear the tank's narrowest side, 8⅜ in (21 cm), plus room for your hands. The 16 3/16 in length only matters on tight turns in halls and stairs. Empty, it weighs about 7 lb (Aqueon).

Can my floor hold a 5 gallon?

Set up, it puts about 56 lb on 0.9 sq ft, or about 60 lb per square foot, before the stand. US homes are designed for 40 lb per square foot spread over a whole living-room floor (IRC Table R301.5), so a tank concentrates its weight. Under about 400 lb, any sound floor normally takes it. That weight band is our rule of thumb, not a code limit. Check your exact setup.

Equipment for a 5 gallon

Rules of thumb, not guarantees. Fish choice, room temperature and filter type all change the right answer.

What a 5 gallon is good for

A 5½ gallon is the smallest tank commonly sold for one betta, and suits shrimp and snails. Care guides recommend more room for a betta (SeriouslyFish suggests a base of about 45 × 30 cm, close to a 10 gallon), and it's too small for goldfish or schooling fish. Check any mix in the stocking calculator.

How the numbers are worked out

Worked examples

Aqueon 5 gallon, 1/8 in glass, 1 in gap, 2 in sand: inside 15.94 × 8.125 in, water height 10.5 − 0.125 − 1 − 2 = 7.375 in. 15.94 × 8.125 × 7.375 = 955 in³ ÷ 231 = 4.1 gal (15.6 L).

Marineland 5 gallon, 1/8 in glass, 1 in gap, 2 in sand: inside 16 × 8.188 in, water height 10.125 − 0.125 − 1 − 2 = 7 in. 16 × 8.188 × 7 = 917 in³ ÷ 231 = 4.0 gal (15.0 L).

Bare-bottom Aqueon 5 gallon, 1/8 in glass, 1 in gap, 0 in sand: inside 15.94 × 8.125 in, water height 10.5 − 0.125 − 1 − 0 = 9.375 in. 15.94 × 8.125 × 9.375 = 1,214 in³ ÷ 231 = 5.3 gal (19.9 L).

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Sources

• Aqueon aquarium size and weight chart, aqueon.com (PDF): www.aqueon.com
• Marineland standard aquariums, Bluefish Aquarium (dealer): bluefishaquarium.com
• Marineland 5.5 Gallon ML10050, Bluefish Aquarium: bluefishaquarium.com
• Aquarium Weights & Sizes, SaltwaterAquarium.com: www.saltwateraquarium.com
• All accessed 29 Sep 2026. Calculations by TankRatio; “estimate” and “rule of thumb” figures are ours.