📐 Aquarium Tank Volume Calculator
Calculate exact water volume from your tank dimensions. Supports multiple tank shapes.
Results
Outer Volume
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Raw L × W × H dimensions
Outer (Liters)
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Water Volume
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After subtracting glass
Water (Liters)
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Glass Displacement
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Actual Water Volume
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After glass + rock/substrate displacement — use this for dosing & salt mix
Actual (Liters)
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Rock/Substrate
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Outer: L × W × H ÷ 231
Water: (L − 2t) × (W − 2t) × (H − t) ÷ 231 (t = glass thickness)
Actual: Water volume × (1 − displacement%)
Why it matters: Dosing, salt mix, and medication calculations must use actual water volume — not the tank's marketed gallon size.
Water: (L − 2t) × (W − 2t) × (H − t) ÷ 231 (t = glass thickness)
Actual: Water volume × (1 − displacement%)
Why it matters: Dosing, salt mix, and medication calculations must use actual water volume — not the tank's marketed gallon size.
How to Calculate Aquarium Volume
Knowing your exact water volume is essential for dosing medications, calculating salt mix, sizing equipment, and determining stocking levels. This calculator accounts for displacement from rock, sand, and decorations.
Standard Tank Dimensions
| Tank | Dimensions (L×W×H) | Gallons |
|---|---|---|
| 10 Gallon | 20×10×12" | 10 |
| 20 Long | 30×12×12" | 20 |
| 40 Breeder | 36×18×16" | 40 |
| 55 Gallon | 48×13×21" | 55 |
| 75 Gallon | 48×18×21" | 75 |
| 125 Gallon | 72×18×21" | 125 |
Displacement Guidelines
For reef tanks with live rock, subtract 10-15% of total volume. A typical reef tank with 1-1.5 lbs of rock per gallon displaces about 10% of total volume. Sand beds displace an additional 3-5%.