Aquarium Calculator
Calculate tank volume, heater size, fish capacity, and substrate requirements
Tank Specifications
Calculation Results
Tank Volume
Heater Requirements
Fish Stocking Guidelines
Substrate & Maintenance
Enter your tank dimensions above and click "Calculate" to see detailed aquarium requirements and recommendations.
When to Use Aquarium Calculator
New Aquarium Setup
Planning a new aquarium? Calculate exact water volume, heater requirements, and fish capacity before purchasing equipment and livestock for your tank.
Heater Sizing
Determine the correct heater wattage for your tank size and desired temperature. Proper heating is crucial for tropical fish health and prevents temperature fluctuations.
Fish Stocking Plans
Avoid overcrowding by calculating appropriate fish quantities for your tank volume. Different fish types have varying space requirements for optimal health.
Water Treatment Dosing
Calculate precise medication and water conditioner doses based on actual water volume. Accurate dosing prevents under or over-treatment of your aquarium.
Substrate Planning
Calculate how much gravel or sand you need for proper substrate depth. Correct substrate amounts ensure adequate biological filtration and plant anchoring.
Equipment Upgrades
Upgrading your aquarium equipment? Ensure new heaters, filters, and lighting are properly sized for your tank volume and livestock requirements.
Frequently Asked Questions
How do I calculate my aquarium volume?
For rectangular tanks, multiply length × width × height. For round tanks, use π × radius² × height. Our calculator handles different tank shapes automatically and provides results in gallons and liters. Remember to account for water level - most aquariums are filled to 90% of their height.
What size heater do I need for my fish tank?
The general rule is 2.5-5 watts per gallon of water. For tropical fish tanks, use 5 watts per gallon in colder rooms (below 65°F), and 2.5 watts per gallon in warmer environments. For larger tanks over 40 gallons, consider using two smaller heaters for better heat distribution and backup protection.
How many fish can I put in my aquarium?
For tropical community fish, use the 1 inch of fish per gallon rule as a starting point. Goldfish need 20 gallons for the first fish and 10 gallons for each additional fish. Large cichlids require 10-15 gallons per fish. Always consider adult fish size, bioload, and territorial requirements when stocking.
How much substrate do I need for my aquarium?
For a 2-3 inch substrate depth, you need approximately 1-2 pounds of gravel per gallon of tank capacity. Sand requires about 1 pound per gallon for the same depth. Deeper substrates (3-4 inches) are needed for planted tanks and certain fish species that like to burrow.
Should I account for decorations when calculating water volume?
Yes, decorations, plants, and substrate displace water. Subtract 10-15% from your calculated volume for more accurate results when planning filtration and water treatments. Heavy decorations like large rocks or driftwood can displace significant amounts of water.
Can this calculator work with different tank shapes?
Yes, our calculator supports rectangular, cylindrical, and bow-front aquarium shapes. Each shape uses the appropriate mathematical formula for accurate volume calculations. For irregular or custom tank shapes, use the rectangular option with average dimensions for an estimate.
Is this aquarium calculator free to use?
Yes, this aquarium calculator is completely free to use. There are no registration requirements, hidden fees, or usage limits. All calculations are performed in your browser for privacy and instant results. You can bookmark the page for future tank planning projects.
How accurate are the fish stocking recommendations?
The stocking guidelines provide conservative estimates based on established aquarium principles. Actual capacity depends on filtration quality, maintenance frequency, fish species compatibility, and experience level. Always research specific fish requirements and consider starting with fewer fish than the maximum recommendation.
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