75 Gallon Tank Dimensions: Size, Weight and Footprint
Published: 2026-10-19 · FishyKart Blog
A standard 75 gallon tank is 4 feet long, 1 1/2 feet deep and 1 3/4 feet tall. Aqueon lists its standard 75 at 48 1/2 x 18 1/2 x 21 1/8 inches (123.2 x 47.0 x 53.7 cm) outside, 98 lb empty and about 785 lb filled. The 18 1/2 inch depth is what sets it apart from a 55 gallon of the same length, and it decides which fish the tank can hold.
Photo: The Wandering Angel - Wikimedia Commons, CC BY 2.0
75 Gallon Tank Specs
| Measure | Standard 75 gallon (Aqueon) |
|---|---|
| Length | 48 1/2 in (123.2 cm) |
| Width (front to back) | 18 1/2 in (47.0 cm) |
| Height | 21 1/8 in (53.7 cm) |
| Footprint | 897 sq in (6.23 sq ft) |
| Empty weight | 98 lb (44 kg) |
| Filled weight | About 785 lb (356 kg) |
| Nominal volume | 75 US gallons = 284 liters = 62.5 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.
Real Water Volume
Aqueon's outside dimensions multiply out to 82.1 gallons of gross volume, more than the label, because they include the glass and frame. Take away a 2 inch gravel bed and leave the water 1 inch below the rim, and the tank holds about 70 gallons (266 liters) of water. That is the number to use for dosing conditioner and medication and for planning water changes: 25% is about 17 to 18 gallons. To check your own setup, use the aquarium volume calculator.
Weight and Where to Put It
At about 8.3 lb per gallon (derived from the USGS water density table), 75 gallons of water weigh roughly 624 lb. With 98 lb of glass and typical gravel and decor, Aqueon puts the filled tank at 785 lb; heavy rock can add more, and the stand comes on top of that.
Because the footprint is wide, that weight is spread over 6.23 square feet, about 126 lb per square foot, which is actually less concentrated than a 55 gallon (about 146 lb per square foot on its narrow base). It is still a heavy point load for a home floor, so the same rules apply: put it against a wall, run the 48 inch length across the floor joists, prefer the ground floor, and ask a contractor or structural engineer about upper floors and older houses. This is general information, not a structural assessment.
75 vs 55, 90 and 125 Gallon
| Tank | L x W x H (inches) | Footprint | Empty / filled |
|---|---|---|---|
| 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 |
| 125 gallon | 72 1/2 x 18 1/2 x 23 1/8 | 9.31 sq ft | 177 / 1,400 lb |
Dimensions and weights: Aqueon "Critical dimensions" table. Footprints calculated by FishyKart.
- 75 vs 55: same length and height, but 5 3/4 inches more depth and 46% more floor area. That depth lets territorial fish set up separate zones and gives large fish room to turn.
- 75 vs 90: the 90 sits on the same stand footprint and is only 4 inches taller. You gain 15 gallons and 265 lb of filled weight, but no swimming length or surface area, and the extra height makes reaching the bottom harder.
- 75 vs 125: the 125 is the step up in length, 6 feet instead of 4, with the same 18 1/2 inch depth. It is the size for fish that outgrow a 4 foot tank, such as a pair of adult oscars.
Fish That Need a 75 Gallon
The 75 gallon is the minimum size on many of our large-fish guides. A single adult oscar needs at least 75 gallons and a 4 foot length (two oscars need 125). Adult green terror cichlids need about 75 gallons, a group of 5 to 6 adult discus needs 75 gallons or more in a tall tank, and peacock and hap African cichlids do better in a 75 than in a 55. A rainbow shark in a community tank is also more settled with the extra floor area.
Before You Buy a 75
- The tank alone is 98 lb and awkward to carry: plan for two or three people to move it, and never move it with water or gravel inside.
- Use a stand made and rated for a 75 gallon (48 1/2 x 18 1/2 inch top); a 55 gallon stand is too shallow.
- Leave room behind the tank for filter hoses and above it for your arms: the bottom is 21 inches down.
- Lids, lights and backgrounds for 48 inch tanks fit the length, but check the front to back size for an 18 inch deep tank.