Aquarium Tank Sizes
Every standard tank size in one table — dimensions, real water volume, and the equipment it needs. Each column is calculated with our own tools at a 68°F room and 78°F target, 2″ of gravel, so you can compare sizes at a glance before opening a calculator.
| Tank | Dimensions (L×W×H) | Nominal | Actual water (90%) | Heater | Filter flow | Substrate (2″) | Est. total weight | Example fish |
|---|---|---|---|---|---|---|---|---|
| 5 gallon | 16 × 8 × 10″ | 5.54 gal | 4.99 gal | 25 W | 22 GPH (84 LPH) | 4.2 L / 256 cu in | 66.64 lb | Betta, Celestial Pearl Danio, Cherry Shrimp, Mystery Snail |
| 10 gallon | 20 × 10 × 12″ | 10.39 gal | 9.35 gal | 50 W | 42 GPH (157 LPH) | 6.55 L / 400 cu in | 113.63 lb | Betta, Neon Tetra, Guppy, Harlequin Rasbora |
| 15 gallon | 24 × 12 × 12″ | 14.96 gal | 13.46 gal | 50–75 W | 60 GPH (227 LPH) | 9.44 L / 576 cu in | 157.53 lb | Betta, Neon Tetra, Guppy, Harlequin Rasbora |
| 20 gallon High | 24 × 12 × 16″ | 19.95 gal | 17.95 gal | 75 W | 80 GPH (302 LPH) | 9.44 L / 576 cu in | 201.49 lb | Betta, Neon Tetra, Guppy, Bronze Corydoras |
| 20 gallon Long | 30 × 12 × 12″ | 18.7 gal | 16.83 gal | 75 W | 75 GPH (283 LPH) | 11.8 L / 720 cu in | 194.04 lb | Betta, Neon Tetra, Guppy, Bronze Corydoras |
| 29 gallon | 30 × 12 × 18″ | 28.05 gal | 25.25 gal | 100–150 W | 112 GPH (425 LPH) | 11.8 L / 720 cu in | 275.65 lb | Betta, Neon Tetra, Guppy, Bronze Corydoras |
| 30 gallon | 36 × 12 × 16″ | 29.92 gal | 26.93 gal | 100–150 W | 120 GPH (453 LPH) | 14.16 L / 864 cu in | 295.4 lb | Betta, Neon Tetra, Guppy, Angelfish |
| 40 gallon Breeder | 36 × 18 × 16″ | 44.88 gal | 40.39 gal | 150–200 W | 180 GPH (680 LPH) | 21.24 L / 1,296 cu in | 427.6 lb | Betta, Neon Tetra, Guppy, Angelfish |
| 40 gallon Long | 48 × 12 × 16″ | 39.9 gal | 35.91 gal | 150 W | 160 GPH (604 LPH) | 18.88 L / 1,152 cu in | 389.31 lb | Betta, Neon Tetra, Guppy, Angelfish |
| 55 gallon | 48 × 13 × 21″ | 56.73 gal | 51.05 gal | 200–250 W | 227 GPH (859 LPH) | 20.45 L / 1,248 cu in | 533.67 lb | Betta, Neon Tetra, Guppy, Angelfish |
| 75 gallon | 48 × 18 × 21″ | 78.55 gal | 70.69 gal | 250–300 W | 314 GPH (1,189 LPH) | 28.32 L / 1,728 cu in | 719.49 lb | Betta, Neon Tetra, Guppy, Angelfish |
| 90 gallon | 48 × 18 × 25″ | 93.51 gal | 84.16 gal | 300–400 W | 374 GPH (1,416 LPH) | 28.32 L / 1,728 cu in | 843.79 lb | Betta, Neon Tetra, Guppy, Angelfish |
| 100 gallon | 60 × 18 × 21″ | 98.18 gal | 88.36 gal | 300–400 W | 393 GPH (1,486 LPH) | 35.4 L / 2,160 cu in | 893.85 lb | Betta, Neon Tetra, Guppy, Angelfish |
| 125 gallon | 72 × 18 × 21″ | 117.82 gal | 106.04 gal | 400–500 W | 471 GPH (1,784 LPH) | 42.48 L / 2,592 cu in | 1,068.21 lb | Betta, Neon Tetra, Guppy, Angelfish |
Figures are planning estimates. Use the individual calculators for your exact dimensions, filtration, and temperature targets.
Frequently asked questions
What are the dimensions of a 55 gallon tank?
A standard 55 gallon aquarium is about 48 × 13 × 21 inches. Long, shallow tanks like this suit fast, mid-water swimmers, while taller tanks favour tall-bodied fish such as angelfish.
Why is actual water volume lower than the tank size?
Nominal capacity assumes filling to the brim. Real tanks are filled to the frame line and lose volume to glass thickness, substrate, and hardscape — typically 10–15% less than the label.
What heater do I need for a 40 gallon tank?
Sizing depends on the temperature rise, not just volume. For a 40 gallon tank in a 68°F room heated to 78°F, our calculator suggests roughly a 100–150 W heater; use the Heater Calculator for your exact numbers.
Related tools
Last reviewed: · canonical https://aquariumforge.com/tank-sizes/