What is an Aquarium Volume Calculator?
An aquarium volume calculator computes the exact water volume of fish tanks in gallons and litres. Calculating net water capacity is vital for stocking fish, dosing water treatments, and sizing filtration systems.
For aquatic care standards, visit Aquarium Volume Standards (Wikipedia).
Aquarium Volume Formulas
Rectangular Tank (Inches to US Gallons):
Volume (US Gal) = (Length × Width × Height in inches) / 231
Metric Tank (Centimeters to Litres):
Volume (Litres) = (Length × Width × Height in cm) / 1,000
How to Calculate Aquarium Capacity
- Measure Inside Dimensions: Record inside glass length, width, and height.
- Calculate Gross Capacity: Divide cubic inches by 231 for US Gallons or cubic cm by 1,000 for Litres.
- Subtract Substrate Displacement: Deduct 10-15% for gravel, rock aquascaping, and driftwood.
- Use Net Volume for Dosing: Calculate medication and water conditioner using net volume.
Aquarium Calculation Example
For a standard 40 Gallon Breeder aquarium measuring 36 inches long, 18 inches wide, and 16 inches high:
Gross Volume = (36 × 18 × 16) / 231 = 10,368 / 231 ≈ 44.88 US GallonsNet Volume (after 10% displacement) = 44.88 × 0.90 ≈ 40.39 US Gallons
Standard Aquarium Size & Gallon Chart
| Aquarium Name | Dimensions (L × W × H in inches) | US Gallons | Litres |
|---|---|---|---|
| 10 Gallon Standard | 20" × 10" × 12" | 10 gal | 38 L |
| 20 Gallon Long | 30" × 12" × 12" | 20 gal | 75 L |
| 40 Gallon Breeder | 36" × 18" × 16" | 40 gal | 151 L |
| 55 Gallon Standard | 48" × 13" × 21" | 55 gal | 208 L |
| 75 Gallon Aquarium | 48" × 18" × 21" | 75 gal | 284 L |
Aquarium Substrate & Water Weight Safety
Water weighs 8.34 lbs per gallon. A 55-gallon aquarium weighs over 600 lbs filled with gravel. Position tanks on level load-bearing stands.