20 gallon high fish tank: dimensions, weight & setup
A standard 20 gallon high tank measures 24 × 12 × 16 inches, holds about 17.6 gallons of real water and weighs roughly 195 lb once set up. It is a great size for planted displays and small communities where floor space is tight.
20 Gallon High tank dimensions
| Inches | Centimeters | |
|---|---|---|
| Length | 24 in | 61.0 cm |
| Width (front to back) | 12 in | 30.5 cm |
| Height | 16 in | 40.6 cm |
| Footprint | 288 in² (2.0 ft²) | 1,858 cm² |
| Typical glass | 3/16 in | 5 mm |
These are typical outside dimensions for US glass tanks; brands vary slightly, so measure yours before buying a stand, lid or background.
How much water does it really hold?
| US gallons | Liters | |
|---|---|---|
| Outside dimensions | 19.9 | 75.5 |
| Filled 1 in below the rim | 17.6 | 66.7 |
| With 2 in of gravel | 15.2 | 57.7 |
Dose medication and fertilizer for the real water — about 15 gallons once the tank is aquascaped, not 20.
How much does a 20 gallon high tank weigh?
| Empty (estimated, 3/16 in glass) | 27 lb | 12 kg |
|---|---|---|
| Filled with fresh water | 174 lb | 79 kg |
| Set up, fresh water + 2 in gravel | 193 lb | 87 kg |
| Set up as saltwater | 196 lb | 89 kg |
| Floor load under the stand | 96 lb/ft² | 4.6 kPa |
Add rock, decor and the stand (often 40–120 lb). A floor load of 96 lb/ft² is 2.4× the 40 lb/ft² a typical home floor is designed for when averaged over a room, so place the stand across the joists and near a load-bearing wall. Use the weight calculator to include your own rock and stand.
Heater size
| Room temperature (water at 78 °F) | Heater |
|---|---|
| 73 °F (5 °F lift) | 50 W |
| 68 °F (10 °F lift) | 75 W |
| 63 °F (15 °F lift) | 100 W |
Colder room, nano heater or dual-heater setup? See the 20 gallon heater size chart.
Plan maintenance with the water change schedule: a 30% change on this tank is about 4.6 gallons.
Filter flow
| Tank type | Real flow | Filter rating |
|---|---|---|
| Community tropical | 70–106 GPH | 101–151 GPH |
| Planted tank | 88–141 GPH | 126–201 GPH |
| Goldfish, cichlids or heavy feeders | 141–176 GPH | 201–252 GPH |
Substrate
| Depth | Gravel | Sand |
|---|---|---|
| 1 in (2.5 cm) | 16 lb | 15 lb |
| 2 in (5.1 cm) | 32 lb | 31 lb |
| 3 in (7.6 cm) | 48 lb | 46 lb |
Stocking ideas
- 1 dwarf gourami + 8 harlequin rasboras + 6 pygmy corydoras
- 1 betta + 6 neon tetras + 1 nerite snail
- 6 platies + 6 pygmy corydoras
Check any combination — including temperature and group size — in the stocking calculator.
Setup tips
- A 20 high has the same 24 × 12 inch footprint as a 15 gallon, so bottom dwellers get no more room — choose a 20 long for corydoras groups.
- The extra height suits stem plants and driftwood, but needs a stronger light to reach the bottom.
- Less surface area than a 20 long means slower gas exchange: let the filter ripple the surface.
FAQ
What are the dimensions of a 20 gallon high fish tank?
A standard 20 gallon high glass tank measures 24 × 12 × 16 inches (61.0 × 30.5 × 40.6 cm) on the outside, a footprint of 2.0 square feet. Brands differ by up to about half an inch.
How much does a 20 gallon high fish tank weigh?
About 25 lb empty, 175 lb filled with water and roughly 195 lb set up with 2 inches of gravel, before rock, decor and the stand.
How many gallons does a 20 gallon high tank really hold?
19.9 gallons by its outside dimensions, about 17.6 gallons (67 liters) filled an inch below the rim, and about 15.2 gallons with 2 inches of gravel.
What size heater does a 20 gallon high tank need?
75 W to hold 78 °F in a 68 °F room; 50 W in a 73 °F room and 100 W in a 63 °F room.
How much gravel or sand for a 20 gallon high tank?
About 16 lb of gravel per inch of depth: 32 lb for a 2-inch bed, or 31 lb of sand.
What filter flow does a 20 gallon high tank need?
70–106 GPH of real flow for a community tank (4–6× turnover), so choose a filter rated about 101–151 GPH.