RediCalc.com
Advertisement
320 × 100 Mobile Banner

Aquarium Volume Calculator

Calculate aquarium volume in gallons and liters for proper stocking.

Last updated: June 13, 2026

Calculator

inches
inches
inches

Results

Volume49.9 gallons
Volume (liters)188.8 L
Approx. Fish Capacity49 inches of fish (1 in/gal rule)
Water Weight416 lbs

How to Use This Calculator

  1. 1Enter tank length in inches.
  2. 2Enter tank width in inches.
  3. 3Enter tank height in inches.
  4. 4View volume in gallons, liters, and stocking capacity.

Formula Explanation

Aquarium volume is calculated from rectangular dimensions and converted to gallons (231 cubic inches per gallon).

Volume (gallons) = (L × W × H) ÷ 231

Variables:

LTank length in inches
WTank width in inches
HTank height in inches

Worked Examples

48×12×20 inch tank

  1. 1. Volume = 48 × 12 × 20 = 11,520 cu in
  2. 2. Gallons = 11,520 ÷ 231 = 49.9 gallons
  3. 3. Liters = 49.9 × 3.785 = 188.9 L
Result: ~50 gallons (189 liters)

Why Use This Calculator

  • Size your aquarium properly.
  • Calculate fish stocking capacity.
  • Know water weight for floor support.
  • Determine filter and heater size.
Advertisement
300 × 250 Medium Rectangle

Tips & Best Practices

  • The "1 inch of fish per gallon" rule is a rough guide — research specific species.
  • Actual water volume is 10-15% less than tank volume due to substrate, decorations, and equipment.
  • Water weighs 8.34 lbs per gallon — a 50-gallon tank weighs over 450 lbs filled.
  • Bigger tanks are actually easier to maintain — water chemistry is more stable.

Common Mistakes to Avoid

❌ Overstocking based on tank volume alone.

✅ Consider adult fish size, not purchase size. A 2-inch fish that grows to 12 inches will quickly outgrow a small tank.

❌ Not considering water weight for floor support.

✅ A 75-gallon tank weighs ~700 lbs with water, substrate, and stand. Ensure your floor can support this, especially on upper floors.

Frequently Asked Questions

How many fish can I put in my tank?
The old "1 inch per gallon" rule is very approximate. Better: research each species' space needs. A 20-gallon tank might hold 10-15 small fish or 2-3 medium fish.
What size tank should a beginner start with?
20-30 gallons is ideal for beginners. Too small and water chemistry swings are deadly; too large and maintenance is overwhelming. A 20-gallon long is a great first tank.
Advertisement
300 × 250 Medium Rectangle

Embed This Calculator

Add the Aquarium Volume Calculator to your website for free. Copy the code below and paste it into your HTML.

<iframe src="https://redicalc.com/embed/pets/aquarium-calculator" width="100%" height="600" style="border:none;border-radius:12px;box-shadow:0 1px 3px rgba(0,0,0,0.1);" title="Aquarium Volume Calculator — RediCalc.com" loading="lazy" allowtransparency="true"></iframe>
Preview embedFree to use · Attribution link included

Disclaimer: This calculator is provided for informational and educational purposes only. Results are estimates and should not be used as a substitute for professional advice. RediCalc.com makes no guarantees regarding the accuracy, completeness, or suitability of any calculations. Always consult a qualified professional before making financial, health, construction, or other important decisions.

By using this site, you agree to our Terms of Use and Privacy Policy. © 2026 RediCalc.com. All rights reserved.

320 × 50 Mobile Anchor