30 Gallon Tank Dimensions: Size, Weight and Fish
Published: 2026-11-10 · FishyKart Blog
A standard 30 gallon tank is 3 feet long, about 1 foot deep and 1 1/2 feet tall. Aqueon lists its 30 at 36 1/4 x 12 5/8 x 16 3/4 inches (92.1 x 32.1 x 42.5 cm) outside, 43 lb empty and about 343 lb filled. The 3 foot length is the point: it is the shortest common tank with a full yard of swimming room, which many of our care guides set as the minimum for active fish.
Photo: Netha Hussain - Wikimedia Commons, CC0
30 Gallon Tank Specs
| Measure | Standard 30 gallon (Aqueon) |
|---|---|
| Length | 36 1/4 in (92.1 cm) |
| Width (front to back) | 12 5/8 in (32.1 cm) |
| Height | 16 3/4 in (42.5 cm) |
| Footprint | 458 sq in (3.18 sq ft) |
| Empty weight | 43 lb (20 kg) |
| Filled weight | About 343 lb (156 kg) |
| Nominal volume | 30 US gallons = 114 liters = 25 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. Other brands differ by a fraction of an inch, and some sell a shallower, deeper "30 breeder" shape.
Real Water Volume
The outside dimensions multiply out to 33.2 gallons gross because they include the glass and frame. With a 2 inch gravel bed and the water 1 inch below the rim, a standard 30 holds about 27 gallons (103 liters) of water. Dose conditioner and medication for that amount; a 25% water change is about 7 gallons. To check your own setup, use the aquarium volume calculator.
Weight and Stand
At about 8.3 lb per gallon (derived from the USGS water density table), 30 gallons of water weigh about 250 lb; Aqueon puts the filled tank with gravel and decor at 343 lb. On its 3.18 square foot base that is about 108 lb per square foot, less than a 29 gallon (about 126) because the same weight is spread over a longer base. Use a stand with a 36 x 12 inch top rated for the tank, place it level against a wall, and do not put it on ordinary furniture. This is general information, not a structural assessment.
30 Gallon vs 29, 38 and 40 Breeder
| Tank | L x W x H (inches) | Footprint | Empty / filled |
|---|---|---|---|
| 29 gallon | 30 1/4 x 12 1/2 x 18 3/4 | 2.63 sq ft | 40 / 330 lb |
| 30 gallon | 36 1/4 x 12 5/8 x 16 3/4 | 3.18 sq ft | 43 / 343 lb |
| 38 gallon | 36 1/4 x 12 5/8 x 19 3/4 | 3.18 sq ft | 47 / 427 lb |
| 40 gallon breeder | 36 3/16 x 18 1/4 x 16 15/16 | 4.59 sq ft | 58 / 458 lb |
Dimensions and weights: Aqueon "Critical dimensions" table. Footprints calculated by FishyKart.
- 30 vs 29: almost the same water, but the 30 is 6 inches longer and 2 inches shorter, with 21% more floor area. For fish that swim end to end, the 30 is the better tank.
- 30 vs 38: same footprint and stand, the 38 is 3 inches taller. You gain about 8 gallons, useful for tall fish such as angelfish, but no extra floor area.
- 30 vs 40 breeder: the same 3 foot length, but the breeder is 5 1/2 inches deeper with 44% more floor area. Territorial fish and breeding pairs are happier in the breeder.
Fish That Fit a 30 Gallon
About 30 gallons is the minimum in many of our care guides:
- Gouramis: a pearl gourami needs 30 gallons as a minimum, plus 5 to 10 gallons for each additional fish; a blue gourami needs at least the 36 x 12 inch footprint of a standard 30.
- Barbs: a proper group of 8 or more tiger barbs, or a school of at least 5 rosy barbs.
- Small cichlids: a single blood parrot, or a pair of jewel cichlids or convicts; two breeding pairs need a 40 breeder.
- Cleanup crew: a Siamese algae eater or a bristlenose pleco.
Not for: oscars, large cichlids and fancy goldfish groups beyond two fish, which need the bigger tanks in our goldfish tank size and oscar guides.
Before You Buy a 30
- Check the stand top: 36 x 12 inches for a standard 30. A 29 gallon stand (30 x 12) is too short.
- Lids and lights for 36 inch tanks fit both the 30 and the 38; a 40 breeder needs an 18 inch deep lid.
- If you are choosing between a 29 and a 30, pick by length: the 30 gives 6 more inches of swimming room for almost the same weight.
- Empty the tank completely before moving it.