Aquarium Calculator
Calculate your aquarium's volume in gallons, determine fish capacity, and find the right filter size.
Volume (gallons) = (Length × Width × Height) ÷ 231; Fish Capacity = Volume ÷ Gallons Per Fish; Filter GPH = Volume × 5
Example: 48" × 12" × 20" tank with small fish = 49.9 gallons ÷ 2 = 24 fish, 250 GPH filter needed
How do I calculate aquarium volume?
Multiply length × width × height (inches), then divide by 231 to convert to gallons.
How many fish can I put in my aquarium?
Small fish need 1-2 gallons each, medium fish need 5-10 gallons, large fish need 20-30 gallons.
🔗 Related Calculators
📐 Formula
Volume (gallons) = (Length × Width × Height) ÷ 231; Fish Capacity = Volume ÷ Gallons Per Fish; Filter GPH = Volume × 5
📝 Example Calculation
Example: 48" × 12" × 20" tank with small fish = 49.9 gallons ÷ 2 = 24 fish, 250 GPH filter needed
❓ Frequently Asked Questions
How do I calculate aquarium volume?▼
Multiply length × width × height (inches), then divide by 231 to convert to gallons.
How many fish can I put in my aquarium?▼
Small fish need 1-2 gallons each, medium fish need 5-10 gallons, large fish need 20-30 gallons.