55 Gallon Tank Dimensions and Weight (Empty and Full)
Published: 2026-10-19 · FishyKart Blog
A standard 55 gallon tank is 4 feet long, 1 foot deep and about 1 3/4 feet tall. Aqueon lists its standard 55 at 48 1/4 x 12 3/4 x 21 inches (122.6 x 32.4 x 53.3 cm) outside, weighing 78 lb empty and about 625 lb filled. That weight, sitting on just 4.3 square feet, is the number to plan around before you choose the spot and the stand.
Photo: stapp - Wikimedia Commons, CC BY 2.0
55 Gallon Tank Specs
| Measure | Standard 55 gallon (Aqueon) |
|---|---|
| Length | 48 1/4 in (122.6 cm) |
| Width (front to back) | 12 3/4 in (32.4 cm) |
| Height | 21 in (53.3 cm) |
| Footprint | 615 sq in (4.27 sq ft) |
| Empty weight | 78 lb (35 kg) |
| Filled weight | About 625 lb (283 kg) |
| Nominal volume | 55 US gallons = 208 liters = 45.8 UK gallons |
Source: Aqueon product catalog, "Critical dimensions for all aquariums", checked November 2026: aqueon.com. Metric values, footprint and UK gallons calculated by FishyKart.
Where the 625 Pounds Come From
Fresh water weighs about 8.3 lb per US gallon at room temperature (derived from the USGS water density table), so a full 55 gallons is roughly 458 lb of water. Add 78 lb of glass and frame, and the rest of Aqueon's 625 lb estimate is gravel, rock and decor; Aqueon notes that filled weights vary with substrate and decor. In practice the water is a little less than 55 gallons: the outside dimensions give 55.9 gallons of gross volume, and with 2 inches of gravel and the water 1 inch below the rim, a standard 55 holds about 48 gallons (181 liters). Check your own setup with the aquarium volume calculator.
A heavy rockscape, such as the live rock in a reef tank or the stacked rock of an African cichlid tank, can push the total higher than Aqueon's figure. The stand itself adds more on top.
Floor Load: Is Your Floor Strong Enough?
About 625 lb on a 48 1/4 x 12 3/4 inch base is roughly 146 lb per square foot under the tank. For comparison, the International Residential Code designs living-area floors in US homes for a uniform live load of 40 lb per square foot (Table R301.5), averaged across the whole room. The two numbers are not directly comparable, because floor joists spread a concentrated load to the rest of the floor, but the gap shows why placement matters. Background: JLC, Calculating Live Loads.
- Against a wall, ideally an exterior or load-bearing wall, where the joists are supported, not in the middle of a long span.
- Across the joists, with the 48 inch length perpendicular to them so the weight spreads over three or four joists instead of one or two.
- Ground floor or slab is the simplest choice for a 55 gallon or larger.
- Ask a contractor or structural engineer if the floor is old, bouncy, already sags or the tank will sit on an upper floor next to other heavy furniture. This article is general information, not a structural assessment.
55 vs 33 Long, 75 and 90 Gallon
| Tank | L x W x H (inches) | Footprint | Empty / filled |
|---|---|---|---|
| 33 gallon long | 48 1/4 x 12 3/4 x 13 3/8 | 4.27 sq ft | 46 / 382 lb |
| 55 gallon | 48 1/4 x 12 3/4 x 21 | 4.27 sq ft | 78 / 625 lb |
| 75 gallon | 48 1/2 x 18 1/2 x 21 1/8 | 6.23 sq ft | 98 / 785 lb |
| 90 gallon | 48 1/2 x 18 1/2 x 25 1/8 | 6.23 sq ft | 135 / 1,050 lb |
Dimensions and weights: Aqueon "Critical dimensions" table. Footprints calculated by FishyKart.
The 55 gallon's weak point is its depth. At 12 3/4 inches front to back it has exactly the same footprint as the low 33 gallon long; the extra 22 gallons are all height. The 75 gallon keeps the 4 foot length and height but adds 5 3/4 inches of depth, which gives 46% more floor area and room for rockwork without crowding the front glass. If you are choosing between the two and the space allows, the 75 is the better tank for fish that claim territory or turn around in the width of the tank.
Which Fish Suit a 55 Gallon
A 4 foot, 21 inch tall tank works for many medium community and cichlid setups. On our species pages, a 55 gallon is the suggested size for freshwater angelfish (which like the 21 inch height), a breeding pair of firemouth cichlids, and many mbuna African cichlid setups, and it is a start for young clown loaches that will later need more. It is too small for an adult oscar, which needs at least 75 gallons, and for a group of adult clown loaches.
Before You Buy a 55
- Measure the spot: 48 1/4 inches of wall plus room at the back for filter hoses and at the top for maintenance.
- Buy a stand made and rated for a 55 gallon; a dresser or a bookshelf is not built for 625 lb.
- Lids, lights and backgrounds are sold for 48 inch tanks; check the fit against your measured length.
- Plan water changes: 25% of about 48 gallons of water is 12 gallons each time.