Aquarium Size Calculator
The aquarium size calculator helps you find your tank’s volume, dimensions and weight in seconds. Pick a standard aquarium size from the list or enter your own length, width and height to get the volume in gallons and liters plus an estimated filled weight. It doubles as a quick tank size calculator and aquarium dimensions reference.
Below the calculator you’ll find a standard aquarium dimensions chart covering the most common tank sizes from 10 to 180 gallons. Use it to compare footprints before you buy, since two tanks with the same gallon rating can have very different dimensions and stands.
Formula: Gallons = (L × W × H in inches) ÷ 231
Standard Aquarium Dimensions Chart
These are the most common glass aquarium sizes and their nominal dimensions in inches (length × width × height), with approximate filled weight. Always measure your own tank before buying a stand or lid, and confirm volume with the aquarium volume calculator.
| Tank Size | Dimensions (L × W × H) | Approx. Filled Weight |
|---|---|---|
| 10 gallon | 20″ × 10″ × 12″ | ~111 lb |
| 15 gallon | 24″ × 12″ × 12″ | ~170 lb |
| 20 gallon High | 24″ × 12″ × 16″ | ~225 lb |
| 20 gallon Long | 30″ × 12″ × 12″ | ~225 lb |
| 29 gallon | 30″ × 12″ × 18″ | ~330 lb |
| 40 gallon Breeder | 36″ × 18″ × 16″ | ~458 lb |
| 55 gallon | 48″ × 13″ × 21″ | ~625 lb |
| 75 gallon | 48″ × 18″ × 21″ | ~850 lb |
| 90 gallon | 48″ × 18″ × 24″ | ~1,050 lb |
| 120 gallon | 48″ × 24″ × 24″ | ~1,400 lb |
| 125 gallon | 72″ × 18″ × 21″ | ~1,400 lb |
| 180 gallon | 72″ × 24″ × 25″ | ~2,100 lb |
Frequently Asked Questions
What are standard aquarium dimensions?
Standard glass tanks come in set footprints. A 20 gallon high is 24 by 12 by 16 inches, a 40 breeder is 36 by 18 by 16, a 55 is 48 by 13 by 21, and a 75 is 48 by 18 by 21 inches. See the full standard aquarium dimensions chart above for sizes from 10 to 180 gallons.
How do I find my tank size from its dimensions?
Multiply length by width by height in inches and divide by 231. For example, 48 by 18 by 21 inches is 18,144 cubic inches divided by 231, or about 78 gallons, which is sold as a 75. Enter your dimensions above to calculate it instantly.
Is a 40 breeder better than a 55 gallon?
For most reef tanks, yes. A 40 breeder at 36 by 18 by 16 inches has a wider 18 inch front-to-back footprint and lower height than a 55 at 48 by 13 by 21 inches, giving more usable aquascape space, better light penetration and easier access. The 55 offers more length in a narrower footprint.
