Use this **aquarium tank calculator** to quickly determine the total volume in US Gallons, volume in cubic inches, and the approximate weight of the water in pounds for your rectangular tank, based on its internal dimensions (Length, Width, and Height).
Aquarium Tank Calculator
Calculation Results
Volume in Cubic Inches:
Volume in US Gallons:
Water Weight (Approximate):
Detailed Calculation Steps
Aquarium Tank Calculator Formula
The calculation relies on the basic formula for the volume of a rectangular prism, followed by standard conversion factors for volume and weight.
1. Volume in Cubic Inches:
$$V_{in^3} = \text{Length} \times \text{Width} \times \text{Height}$$
2. Volume in US Gallons:
$$V_{gal} = V_{in^3} / 231$$
3. Water Weight (Lbs):
$$W_{lbs} = V_{gal} \times 8.34$$
Formula Source: Engineering Toolbox – Rectangular Volume | USGS – Water Density
Variables Explained
The calculator requires three primary dimensions, typically measured from the inside of the tank for the most accurate water volume calculation:
- Length (L): The longest side of the tank’s interior base (in inches).
- Width (W): The shortest side of the tank’s interior base, or depth (in inches).
- Height (H): The vertical distance of the water level from the bottom of the tank (in inches).
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- Aquarium Filter Size Calculator
- Heater Wattage Requirement Tool
- Aquatic Lighting PAR Calculator
- Substrate Volume Calculator
What is an Aquarium Tank Calculator?
An **aquarium tank calculator** is a crucial tool used by fish keepers and aquarists to determine the capacity and structural load of their tanks. Knowing the precise volume is essential for everything from dosing medications and supplements to selecting appropriately sized equipment like heaters, filters, and air pumps.
The calculated volume in US Gallons dictates the biological load the tank can safely handle, helping users avoid overstocking fish. Furthermore, the calculated water weight is a critical factor for ensuring the stand or platform supporting the aquarium can safely bear the combined load of the water, glass, substrate, and equipment.
This specific **aquarium tank calculator** simplifies the conversion from cubic inches (a direct result of multiplying inches) to US Gallons, which is the standard unit of measure in the hobby. It provides an immediate and accurate estimate for better planning and safety.
How to Calculate Aquarium Tank Volume (Example)
Consider a tank with internal dimensions of L=36 inches, W=18 inches, and H=20 inches.
- Step 1: Calculate Cubic Inches ($\mathbf{V_{in^3}}$): Multiply the three dimensions: $$36 \text{ in} \times 18 \text{ in} \times 20 \text{ in} = 12,960 \text{ in}^3$$
- Step 2: Convert to US Gallons ($\mathbf{V_{gal}}$): Divide the cubic volume by the conversion factor (231 cubic inches per gallon): $$12,960 \text{ in}^3 / 231 \approx 56.10 \text{ US Gallons}$$
- Step 3: Calculate Water Weight ($\mathbf{W_{lbs}}$): Multiply the volume in gallons by the weight of water per gallon (8.34 lbs/gal): $$56.10 \text{ gal} \times 8.34 \text{ lbs/gal} \approx 467.87 \text{ lbs}$$
- Conclusion: This tank holds approximately 56.1 US gallons of water, weighing nearly 468 pounds.
Frequently Asked Questions (FAQ)
- How do I account for substrate or rocks in the aquarium tank calculator?
- The calculator provides the maximum *water* volume. Substrate, rocks, and equipment displace water, meaning the actual water volume will be slightly less. For precise dosing, measure the final water level height after adding decorations.
- Is the weight calculation accurate for saltwater?
- The calculator uses the weight of freshwater (8.34 lbs/gal). Saltwater is denser. For typical reef salinity (1.025 S.G.), the weight is closer to 8.55 lbs/gal. The difference is minor for stand safety but important for precision.
- Why do my measurements not match the tank’s stated capacity (e.g., a “55 Gallon” tank)?
- Commercial tank sizes are often nominal. Furthermore, this calculator uses *internal* dimensions and assumes the water is filled to the height you entered (H), not necessarily the very top edge of the glass.
- Can this aquarium tank calculator be used for circular or hexagonal tanks?
- No. This calculator is strictly for rectangular (cuboid) tanks. Different geometric formulas are required for other shapes (e.g., $V = \pi r^2 h$ for circular tanks).