10 Gallon Tank Dimensions: Size in Inches, Weight and Footprint
Published: 2026-10-19 · FishyKart Blog
A standard 10 gallon tank measures about 20 x 10 x 12 inches. Aqueon, one of the largest US tank makers, lists its standard 10 gallon at 20 1/4 x 10 1/2 x 12 9/16 inches (51.4 x 26.7 x 31.9 cm) outside, 11 lb empty and about 111 lb filled. Below are the exact numbers, how much water it really holds, and how it compares with the next sizes up.
Photo: JohnstonDJ - Wikimedia Commons, CC BY-SA 3.0
10 Gallon Tank Size at a Glance
| Measure | Standard 10 gallon (Aqueon) |
|---|---|
| Length | 20 1/4 in (51.4 cm) |
| Width (front to back) | 10 1/2 in (26.7 cm) |
| Height | 12 9/16 in (31.9 cm) |
| Footprint | 213 sq in (1.48 sq ft) |
| Empty weight | 11 lb (5 kg) |
| Filled weight | About 111 lb (50 kg) |
| Nominal volume | 10 US gallons = 37.9 liters = 8.3 UK gallons |
Source: Aqueon product catalog, "Critical dimensions for all aquariums" (10 Leader), checked November 2026: aqueon.com. Metric values, footprint and UK gallons calculated by FishyKart.
Other brands sell 10 gallon tanks of nearly the same size, but not always to the fraction of an inch, and kit tanks with curved hoods (like the one in the photo) can be taller. If a lid, light or background has to fit, measure the tank you actually own.
How Much Water a 10 Gallon Really Holds
Multiply Aqueon's outside dimensions (20.25 x 10.5 x 12.56 inches) and divide by 231 cubic inches per gallon, and you get 11.6 gallons of gross volume. The glass, the trim, the gravel and the empty space under the rim take that back down. With a 2 inch layer of gravel and the water 1 inch below the top, a standard 10 gallon holds about 8.8 gallons (33 liters) of water. Use that figure, not "10", when you dose water conditioner or medication. Try your own numbers in the aquarium volume calculator.
Weight: Can Your Furniture Hold It?
About 8.8 gallons of water weigh roughly 73 lb on their own (fresh water is about 8.3 lb per gallon). Aqueon's filled estimate of 111 lb also covers the glass and typical gravel and decor. Spread over a 20 x 10 inch base, that is about 75 lb per square foot, concentrated on the narrow strip of furniture under the tank.
- Use a stand or cabinet that is rated for at least 111 lb and is level; uneven support stresses the glass seams.
- Check that the top is larger than the 20 1/4 x 10 1/2 inch base, so no edge of the tank overhangs.
- Avoid shelves held by brackets or particleboard desks that already sag. Aqueon advises placing any aquarium on a stand designed to carry the weight of the filled tank.
10 Gallon vs 5.5, 20 High and 20 Long
| Tank | L x W x H (inches) | Footprint | Filled weight |
|---|---|---|---|
| 5.5 gallon | 16 3/16 x 8 3/8 x 10 1/2 | 0.94 sq ft | 62 lb |
| 10 gallon | 20 1/4 x 10 1/2 x 12 9/16 | 1.48 sq ft | 111 lb |
| 20 gallon high | 24 1/4 x 12 1/2 x 16 3/4 | 2.11 sq ft | 225 lb |
| 20 gallon long | 30 1/4 x 12 1/2 x 12 3/4 | 2.63 sq ft | 225 lb |
Dimensions and weights: Aqueon "Critical dimensions" table. Footprints calculated by FishyKart.
The 20 gallon long is the natural upgrade: almost the same height as a 10 gallon (12 3/4 vs 12 9/16 inches) but 10 inches longer and with 78% more floor area. For small schooling fish, bottom dwellers like corydoras and anything that swims the length of the tank, the extra length matters more than the extra height of a 20 high. The cost is weight: 225 lb filled, twice the 10 gallon, so it needs a proper aquarium stand.
What a 20 Inch Tank Is Good For
A 20 inch tank suits one small school of nano fish, a single betta, or shrimp and snails. Fish that grow past about 2 inches, or that are fast, active swimmers, run out of room in 20 inches of length. For stocking ideas, see the best fish for a 10 gallon tank and how many fish fit in a 10 gallon tank; for a betta, see betta fish tank size.
When a 10 Gallon Is the Wrong Size
- Goldfish. They grow large and produce heavy waste; see goldfish tank size.
- Fish sold small that grow big, such as plecos, oscars and most cichlids.
- Axolotls need a larger, longer tank and cool water; see axolotl tank setup.
- Beginners who want room for mistakes. Small volumes change temperature and water quality fast; a 20 long is more forgiving.