20 gallon fish tank size and measurements
How big is a 20 gallon tank? It is about 2.0 feet long (24 in), 12 inches from front to back and 16 inches tall, so it needs a stand or space at least 24 x 12 inches.
- Outside dimensions
- 24 x 12 x 16 in61 x 30.5 x 40.6 cm
- Volume
- 20 US gal76 L, 17 UK gal
- Footprint
- 2.0 sq ft288 sq in
- Water weight
- 167 lb76 kg
Measured from the outside, these dimensions hold about 19.9 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 20 gallon tank weigh?
A 20 gallon tank weighs about 225 lb (102 kg) once set up, counting the empty glass (25 lb), the water and 2 inches of gravel. 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 20 gallon tank?
| Bed depth | Gravel | Sand | Aquasoil |
|---|---|---|---|
| 1 in (2.5 cm) | 17 lb | 16 lb | 5 L |
| 2 in (5.1 cm) | 33 lb | 32 lb | 9 L |
| 3 in (7.6 cm) | 50 lb | 48 lb | 14 L |
Based on a 24 x 12 in floor and typical bulk densities.
Different depth? Use the aquarium substrate calculator.
Heater and filter size for a 20 gallon tank
A common rule is 3–5 watts per gallon, so a 20 gallon tank needs about 60–100 W: one 100 W heater 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 80–120 gallons per hour.
Fish that suit a 20 gallon tank
- Small schools of tetras or rasboras
- Honey gouramis
- Platies
- Pygmy or habrosus corydoras
Starting ideas only. Check each species' adult size, temperament and water needs before buying.
Compare nearby sizes
- Next smaller: 10 gallon, 20 x 10 x 12 in
- Next larger: 20 gallon long, 30 x 12 x 12 in
See every size in the aquarium size chart.
Further reading
Frequently asked questions
What are the dimensions of a 20 gallon tank?
A standard 20 gallon aquarium measures about 24 x 12 x 16 inches (61 x 30.5 x 40.6 cm), length x width x height. Brands vary by a fraction of an inch.
How long is a 20 gallon tank?
About 24 inches (61 cm), or 2.0 feet.
How big is a 20 gallon tank?
It is about 2.0 feet long, 12 inches deep and 16 inches tall, and takes up 2.0 square feet of floor.
How much does a 20 gallon tank weigh when full?
About 225 lb (102 kg) once set up, counting the empty glass (25 lb), the water and 2 inches of gravel.
How much gravel do I need for a 20 gallon tank?
For a 2 inch bed, about 33 lb of gravel or 32 lb of sand.
What size heater does a 20 gallon tank need?
About 60–100 watts in total, so one 100 W heater suits most rooms.
Last updated .