100 gallon fish tank size and measurements
How big is a 100 gallon tank? It is about 6.0 feet long (72 in), 18 inches from front to back and 18 inches tall, so it needs a stand or space at least 72 x 18 inches.
- Outside dimensions
- 72 x 18 x 18 in182.9 x 45.7 x 45.7 cm
- Volume
- 100 US gal379 L, 83 UK gal
- Footprint
- 9.0 sq ft1,296 sq in
- Water weight
- 834 lb378 kg
Measured from the outside, these dimensions hold about 101.0 US gallons. Real water volume is lower because of glass thickness, substrate, decor and the gap below the rim. Check the real figure with the aquarium volume calculator.
How much does a 100 gallon tank weigh?
A 100 gallon tank weighs about 984 lb of water and gravel, plus the glass, which varies by brand. Use a stand rated for the full weight, on a level floor. The fish tank weight guide compares every size.
How much gravel or sand for a 100 gallon tank?
| Bed depth | Gravel | Sand | Aquasoil |
|---|---|---|---|
| 1 in (2.5 cm) | 75 lb | 71 lb | 21 L |
| 2 in (5.1 cm) | 150 lb | 142 lb | 42 L |
| 3 in (7.6 cm) | 225 lb | 214 lb | 64 L |
Based on a 72 x 18 in floor and typical bulk densities.
Different depth? Use the aquarium substrate calculator.
Heater and filter size for a 100 gallon tank
A common rule is 3–5 watts per gallon, so a 100 gallon tank needs about 300–500 W: two 200 W heaters, one at each end suits most rooms. Use the higher end in cold rooms.
For filtration, aim to turn the water over 4–6 times an hour: a filter rated around 400–600 gallons per hour.
Fish that suit a 100 gallon tank
- Large schools of active fish
- Cichlid communities
- Larger plecos suited to the size
- Marine fish-only setups
Starting ideas only. Check each species' adult size, temperament and water needs before buying.
Compare nearby sizes
- Next smaller: 90 gallon, 48 x 18 x 24 in
- Next larger: 125 gallon, 72 x 18 x 21 in
See every size in the aquarium size chart.
Frequently asked questions
What are the dimensions of a 100 gallon tank?
A standard 100 gallon aquarium measures about 72 x 18 x 18 inches (182.9 x 45.7 x 45.7 cm), length x width x height. Brands vary by a fraction of an inch.
How long is a 100 gallon tank?
About 72 inches (182.9 cm), or 6.0 feet.
How big is a 100 gallon tank?
It is about 6.0 feet long, 18 inches deep and 18 inches tall, and takes up 9.0 square feet of floor.
How much does a 100 gallon tank weigh when full?
About 984 lb of water and gravel, plus the glass, which varies by brand.
How much gravel do I need for a 100 gallon tank?
For a 2 inch bed, about 150 lb of gravel or 142 lb of sand.
What size heater does a 100 gallon tank need?
About 300–500 watts in total, so two 200 W heaters, one at each end suits most rooms.
Last updated .