Aquarium Volume Calculator

Calculate your aquarium’s water volume quickly with our Aquarium Volume Calculator. Get accurate tank capacity based on shape and dimensions!

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Aquarium Volume Calculator: A Comprehensive Guide

The process of determining tank volume plays a vital role in aquatic environment health for aquarium hobbyists. There is a need to understand how to calculate aquarium water volume because it maintains a safe environment for aquatic plants as well as fish. Accurately determining the water capacity in your tank is essential, whether you have a rectangular standard tank or an unusual aquariophilic vessel. The following guide explains accurate aquarium volume measurements along with calculations for non-rectangular shapes and also provides standard aquarium measurements as well as methods for calculating the tank weight after filling.

Why Is Aquarium Volume Important?

For different purposes, you must determine the exact volume measurement of your aquarium.
Here we are going to understand why the volume of the aquarium is important. It is about how to find out how many liters of water an aquarium can hold because you need to know this if you have an aquarium. The reason for this is that if you know how much water our aquarium holds, then you will be able to install the heater in the right proportion. Apart from this, you will also know which filter to use and the most important thing is how much medicine we should put in it. If you do not know how many liters of water our aquarium holds, then you put the medicine also by guessing. Apart from this, you also don’t know how much salt to put in, so it is important to understand the volume of the aquarium.
Risks should measure aquarium water volume before deciding the appropriate quantity of dechlorination and conditioners together with medicines.
Fish that are overstocked will experience stress together with disease development and degeneration of water quality. A tank that fits its inhabitants properly leads to an optimal aquatic environment.
Tank volume determines how filters get rated in the aquarium market. The wrong choice of filter will directly affect water quality standards.
Regular care maintenance depends on understanding total water volume as a basis for deciding necessary water percentage changes.
Understanding the complete filled tank weight becomes vital since water presents a heavy weight that requires proper surface selection for placement.

How to Calculate Aquarium Volume

Rectangular Aquarium Volume Calculation

Volume=Length×Width×Height

If you measured in inches, convert the volume to gallons using this formula:

Volume in gallons = \frac{Volume in cubic inches}{231}

If you measured in centimeters, convert to liters like this:

Volume in liters = \frac{Volume in cubic centimeters}{1000}

Example Calculation

Volume (Litters) = Length (cm) × Width (cm) × Height (cm) /1000

Volume (Gallons) = Length (in) × Width (in) × Height (in) /231

A rectangular tank measuring 90 cm long, 40 cm wide, and 50 cm high:

(90 × 40 × 50)/1000 = 180 Litters.

For inches: 36 in × 16 in × 20 in:

(36 × 16 × 20)/231 = 49.7 Gallons.

Typical Aquarium Sizes & Their Volumes

Most aquarium manufacturers offer standard tank sizes. Here are some common dimensions:

Tank Size	Dimensions (L × W × H) Inches	Volume (Gallons)	Volume (Liters)
10 Gallon	20" × 10" × 12"	10	38
20 Gallon	24" × 12" × 16"	20	76
30 Gallon	36" × 12" × 16"	30	113.27
40 Gallon	36" × 18" × 16"	40	151
55 Gallon	48" × 13" × 21"	55	208
75 Gallon	48" × 18" × 21"	75	283
125 Gallon	72" × 18" × 23"	125	473

These sizes are widely available, but custom aquariums may have different dimensions.

Calculating Volume for Non-Rectangular Aquariums

2. Cylindrical Aquarium

Common in round fish bowls or cylindrical tanks. Measure the radius (half the diameter) and the height.

Formula:

Volume = π \times {Radius}^{2} \times Height

For gallons: Divide the volume in cubic inches by 231.
$Volume (gallons) = \frac{π \times {Radius}^{2} \times Height}{231}$
For liters: Divide the volume in cubic centimeters by 1,000.
$Volume (liters) = \frac{π \times {Radius}^{2} \times Height}{1000}$

3. Bow-Front Aquarium

Bow-front tanks have a curved front, so the calculation is a bit more complex. You’ll need to measure the length, width, height, and the depth of the bow.

Formula:

Volume = (Length \times Width \times Height) + (\frac{Bow Depth \times Length \times Height}{2})

For gallons: Divide the volume in cubic inches by 231.
$Volume (gallons) = \frac{(Length \times Width \times Height) + (\frac{Bow Depth \times Length \times Height}{2})}{231}$
For liters: Divide the volume in cubic centimeters by 1,000.
$Volume (liters) = \frac{(Length \times Width \times Height) + (\frac{Bow Depth \times Length \times Height}{2})}{1000}$

4. Hexagonal Aquarium

Hexagonal tanks have six sides. Measure the length of one side, the height, and the apothem (the distance from the center to the midpoint of one side).

Formula:

$Volume = 3 \times Side Length \times Apothem \times Height$
For gallons: Divide the volume in cubic inches by 231.
$Volume (gallons) = \frac{3 \times Side Length \times Apothem \times Height}{231}$
For liters: Divide the volume in cubic centimeters by 1,000.
$Volume (liters) = \frac{3 \times Side Length \times Apothem \times Height}{1000}$

5. Corner Pentagonal Aquarium

Corner tanks often have five sides. Measure the length of the front panel, the height, and the depth.

Formula:

$Volume = \frac{5}{2} \times Front Length \times Depth \times Height$
For gallons: Divide the volume in cubic inches by 231.
$Volume (gallons) = \frac{\frac{5}{2} \times Front Length \times Depth \times Height}{231}$
For liters: Divide the volume in cubic centimeters by 1,000.
$Volume (liters) = \frac{\frac{5}{2} \times Front Length \times Depth \times Height}{1000}$

6. Spherical Aquarium

Spherical tanks (like fish bowls) require measuring the radius (half the diameter).

Formula:

$Volume = \frac{4}{3} \times π \times {Radius}^{3}$
For gallons: Divide the volume in cubic inches by 231.
$Volume (gallons) = \frac{\frac{4}{3} \times π \times {Radius}^{3}}{231}$
For liters: Divide the volume in cubic centimeters by 1,000.
$Volume (liters) = \frac{\frac{4}{3} \times π \times {Radius}^{3}}{1000}$

7. L-Shaped Aquarium

L-shaped tanks are essentially two rectangular tanks joined together. Measure the dimensions of each section separately and add their volumes.

Formula:

$Volume = ({Length}_{1} \times {Width}_{1} \times Height) + ({Length}_{2} \times {Width}_{2} \times Height)$
For gallons: Divide the total volume in cubic inches by 231.
$Volume (gallons) = \frac{({Length}_{1} \times {Width}_{1} \times Height) + ({Length}_{2} \times {Width}_{2} \times Height)}{231}$
For liters: Divide the total volume in cubic centimeters by 1,000.
$Volume (liters) = \frac{({Length}_{1} \times {Width}_{1} \times Height) + ({Length}_{2} \times {Width}_{2} \times Height)}{1000}$

8. Oval Aquarium

Oval tanks are similar to cylindrical tanks but with an elliptical shape. Measure the longest diameter (major axis), the shortest diameter (minor axis), and the height.

Formula:

$Volume = π \times (\frac{Major Axis}{2}) \times (\frac{Minor Axis}{2}) \times Height$
For gallons: Divide the volume in cubic inches by 231.
$Volume (gallons) = \frac{π \times (\frac{Major Axis}{2}) \times (\frac{Minor Axis}{2}) \times Height}{231}$
For liters: Divide the volume in cubic centimeters by 1,000.
$Volume (liters) = \frac{π \times (\frac{Major Axis}{2}) \times (\frac{Minor Axis}{2}) \times Height}{1000}$

Formula to Estimate Weight

The weight calculation of your aquarium requires considering its internal content as well as the tank’s weight together with the water volume.
Aquarium weight needs careful consideration because it determines how it will rest on stands or designated home locations. The complete weight consists of the water and the tank itself as well as the elements inside the tank.
Calculating the Weight
Water creates an eight-pound pressure effect on each gallon of substance. The water content in a 10-gallon tank equals approximately 83.4 pounds.
The weight of the tank derives from its material selection between glass or acrylic along with the chosen thickness. Glass tanks of 10-gallon capacity usually reach 11 pounds in weight but 55-gallon tanks can grow heavier up to 78 pounds.
The total weight calculation should include gravel along with all decorations and rocks. Gravel alone can add 1-2 pounds of weight per gallon.

Calculation Example

Let’s calculate for a 55 gallon tank:

Water weight: $55 \times 8.34 = 458.7$ pounds

Tank weight: About 78 pounds

Substrate and decorations: Around 55-110 pounds

Total weight: $458.7 + 78 + 55 = 591.7$ pounds (minimum)

That’s a lot of weight, so make sure your stand and floor can handle it!

Estimated Weights for Common Aquariums

Tank Size	Volume (Gallons)	Approx. Weight (kg)
10 Gallon	10	50 kg
20 Gallon	20	90 kg
55 Gallon	55	250 kg
75 Gallon	75	350 kg
125 Gallon	125	600 kg

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Aquarium Volume Calculator: A Comprehensive Guide

Why Is Aquarium Volume Important?

How to Calculate Aquarium Volume

Typical Aquarium Sizes & Their Volumes

Calculating Volume for Non-Rectangular Aquariums

Formula:

Formula:

4. Hexagonal Aquarium

Hexagonal tanks have six sides. Measure the length of one side, the height, and the apothem (the distance from the center to the midpoint of one side).

Formula:

5. Corner Pentagonal Aquarium

Corner tanks often have five sides. Measure the length of the front panel, the height, and the depth.

Formula:

6. Spherical Aquarium

Spherical tanks (like fish bowls) require measuring the radius (half the diameter).

Formula:

7. L-Shaped Aquarium

L-shaped tanks are essentially two rectangular tanks joined together. Measure the dimensions of each section separately and add their volumes.

Formula:

8. Oval Aquarium

Oval tanks are similar to cylindrical tanks but with an elliptical shape. Measure the longest diameter (major axis), the shortest diameter (minor axis), and the height.

Formula:

Formula to Estimate Weight

Calculation Example

Estimated Weights for Common Aquariums

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