120 Gallon tank dimensions
48×24×24inches
Length × width × height. In metric, 121.9 × 61 × 61 cm.
A standard 120 gallon aquarium is 48 inches long, 24 inches front to back and 24 inches tall. Its measurements work out to almost exactly the volume on the label. Once you add gravel and leave a gap at the top, expect a little less water than that.
How much a 120 gallon tank weighs
Empty, the glass tank weighs about 156 pounds. Filled with water and two inches of gravel it comes to roughly 1,281 pounds, before rocks, wood or equipment.
That is the weight of several people standing in one spot for years. Put it on a purpose-built stand, across the floor joists or near a load-bearing wall, and check an upstairs floor before you fill it.
| Empty tank | about 156 lb |
|---|---|
| Water (120 gallons) | 1,001 lb |
| Gravel, 2 inches deep | about 124 lb |
| Filled, with gravel | about 1,281 lb |
| Load on the floor | about 160 lb per sq ft |
Stand, lid, heater and filter sizes
The stand and the lid both follow the footprint, 48 by 24 inches. A stand has to support the whole bottom frame, so it can be bigger than the tank but never smaller.
For a heated tropical tank, a 2 x 250 W heater suits a normal room. Two heaters split the load and fail safer. Pick a filter rated to turn the water over four to six times an hour.
| Footprint | 48 x 24 in (8 sq ft) |
|---|---|
| Volume | 120 gal (454.2 L) |
| Heater | 2 x 250 W |
| Filter flow | 480 to 720 gal per hour |
| Typical glass | about 3/8 in thick |
What fish can live in a 120 gallon tank
How many of each fish would fill this tank on its own. Mix species and the numbers come down, so plan a real community with the calculator.
- Betta1 only
- Neon tetraup to 135
- Ember tetraup to 202
- Guppyup to 67
- Harlequin rasboraup to 90
- Zebra danioup to 81
- Cherry barbup to 81
- Platyup to 81
- Panda coryup to 81
- Bronze coryup to 54
- Honey gouramiup to 6
- Dwarf gourami1 only
- Pearl gouramiup to 4
- Tiger barbup to 67
- Mollyup to 48
- Angelfishup to 6
- Fancy goldfishup to 6
- Bristlenose pleco1 only
- Boeseman's rainbowfishup to 27
- German blue ramup to 2
- Electric yellow labup to 27
- Discusup to 12
- Oscar1 only *
- Common goldfish1 only
* Fits by volume, but the footprint is under what Seriously Fish recommends for the species.
Too big for this tank
- Clown loach needs a bigger tank: the recommended minimum is a 71 x 24 in footprint.
- Common pleco grows too big for this tank.
- Bala shark needs a bigger tank: the recommended minimum is a 94 x 24 in footprint.
Gear for a 120 gallon tank
Searches on Amazon for the right size. Check the tank size or flow rating on the listing before you buy.
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Next sizes down and up
Common questions
How big is a 120 gallon tank?
A standard 120 gallon aquarium is 48 x 24 x 24 inches (121.9 x 61 x 61 cm), length by width by height. Brands differ by up to an inch.
How much does a 120 gallon tank weigh?
About 156 lb empty and roughly 1,281 lb filled with water and two inches of gravel, before rocks, wood and equipment. That puts about 160 lb per square foot on the floor.
What size heater and filter does a 120 gallon tank need?
A 2 x 250 W heater suits a tropical 120 gallon tank in a normal room. Choose a filter rated for 480 to 720 gallons per hour, which turns the water over four to six times an hour.
How many fish can a 120 gallon tank hold?
On its own, it holds up to 135 neon tetras, up to 202 ember tetras, up to 67 guppys. Mixing species brings the numbers down, and a tank at 60 to 80% stocked is easier to keep than a full one. The stocking calculator checks a real mix.