Welcome to the most accurate and easy-to-use aquarium volume calculator. Whether you need to find your fish tank's size, calculate its capacity in gallons / liters, or determine the precise water volume for medication, you're in the right place. Knowing your aquarium’s true volume is the foundation of a healthy, thriving aquatic ecosystem, and this tool is designed to give you that number instantly.
Why Calculating Aquarium Volume is Crucial
In aquatics, precision is everything. An accurate calculation of your aquarium volume & tank's size is critical for:
- Proper Equipment Selection: Heaters, filters, and pumps are all rated for specific tank sizes or water volumes. Knowing your true Tank volume ensures your life support systems are correct for your setup.
- Safe Fish Stocking: Knowing the accurate gallon or liter count is essential for preventing overstocking and maintaining a low-stress environment for your fish.
- Accurate Medication and Dosing: This is the most important reason. Under-dosing medication can be ineffective, while over-dosing can be lethal to your fish, invertebrates, and plants. Our calculator provides the precision you need for safe and effective treatment.
- Water Changes and Maintenance: Knowing your exact water volume allows you to perform precise water changes (e.g., exactly 25%), ensuring you remove enough nitrates without shocking your tank's inhabitants.
Why Our Aquarium Volume Calculator is the Best
While other calculators exist, they often fall short. We built this tool to be the most comprehensive and user-friendly resource for every aquarist, from beginner to expert.
Unmatched Shape Support
Is your tank a standard rectangle, a stunning bowfront, a unique L-shaped prism, or a space-saving corner tank? We’ve got you covered. Our calculator supports an extensive library of 18 different aquarium shapes, ensuring you get a precise calculation for the tank you actually own.
Two Calculators in One: Total Volume & Water Fill
Our tool provides two distinct calculations. The main calculator finds the Total Tank Volume (the full capacity), which is essential for choosing equipment. The separate "Water Fill" calculator finds the true water volume for a specific water height, perfect for calculating water changes or initial fills.
More Than Just Volume: Reverse Calculations
This is also an aquarium dimensions calculator. Have you ever known the volume you want, but needed to figure out the dimensions? Our calculator can work backward. You can enter a desired volume and other known measurements to solve for a missing length, height, or diameter, making it an indispensable tool for planning your next build.
Full Imperial & Metric Unit Support
Whether you are an American, or from the UK, or anywhere around the world, whether you think in gallons and inches or liters and centimeters, our calculator speaks your language. Features include:
- Instantly switch between Imperial and Metric systems using the global tab at the top.
- Mix-and-match units for each dimension (e.g., feet for length, inches for height).
- No more manual conversions. If you enter a value and then change its unit, the calculator automatically converts the number for you.
Intuitive and Visual Design
Every shape you select is accompanied by a clear, labeled diagram. This visual guide ensures you know exactly which measurement corresponds to each input field, eliminating guesswork and giving you confidence in your results.
Complete Support for All Tank Shapes & Units
Tank Shapes
To ensure we cover virtually any aquarium, our calculator includes precise formulas for the following shapes, categorized for your convenience.
Rectangular & Prism Shapes
- Cuboid / Rectangle - The most common aquarium shape.
- Cube / Cubic - A tank with equal length, width, and height.
- Hexagonal Prism / Hexagon - A six-sided tank.
- Octagonal Prism / Octagon - An eight-sided tank.
- Triangular Prism / Triangle - A tank with a custom triangular base.
- Trapezoidal Prism / Trapezoid - A four-sided tank with a wider back and narrower front.
Corner & Wall Shapes
- Corner Cylinder / Quarter Cylinder / Corner Bowfront - Fits perfectly into a 90-degree corner.
- Corner Pentagon - A five-sided tank designed for corners.
- Corner Triangle / Right-Angle Corner - A three-sided tank for maximizing corner space.
- L-Shaped Prism / L-Tank - Two rectangular tanks joined to form an 'L' shape.
- Flat-Back Hexagon - A six-sided tank with a flat back for placement against a wall.
- Flat-Back Bullnose / D-Shape / Flat-Back Half Moon - A D-shaped tank with one flat side.
Cylindrical & Curved Shapes
- Cylinder / Round / Tube - A circular tank with straight sides.
- Half Cylinder / Half Moon / Semi-Circle - A semi-circular tank, perfect for placing against a wall.
- Bowfront - A rectangle with a curved front pane.
- Double Bullnose / Racetrack / Capsule - A rectangle with a semi-circle on both ends.
- Elliptical Prism / Oval / Ellipse - A tank with an elliptical base.
- Spherical Bowl / Fishbowl - A classic round fishbowl.
Supported Units
For complete flexibility, you can mix and match any of the following units of measurement:
Linear Units (for Length, Width, Height)
- Meters (m)
- Centimeters (cm)
- Millimeters (mm)
- Feet (ft)
- Inches (in)
Volume Units (for Water Capacity)
- Liters (L) - A standard Metric unit for volume.
- Cubic Meters (m³) - The base unit for volume in the Metric system.
- US Gallons (gal) - The standard gallon measurement used in the United States.
- Imperial Gallons (gal) - The gallon measurement used in the United Kingdom and other regions.
- Cubic Feet (ft³)
- Cubic Inches (in³)
How to Use This Calculator
Getting a precise calculation takes only a few seconds:
- Select Your Aquarium's Shape: Choose from the visual library of 18 shapes.
- Choose What to Calculate: Use the "Calculate" dropdown to find the Volume or to solve for a specific dimension like Height or Length.
- Enter Your Dimensions: Use the dropdown next to each field to select the appropriate unit (in, cm, ft, etc.) and fill in the known measurements.
(Inserting measurement first, and then changing the unit will auto convert the input value from the previous unit to the new unit) - Get Your Instant Result: Your answer appears in the final field in real-time.
Frequently Asked Questions (FAQ)
How is this different from a standard aquarium calculator?
While it perfectly calculates aquarium volume in gallons and liters (supports US, UK and international units), it's also a complete tank size calculator. It supports far more shapes and can solve for dimensions, not just volume.
Do I need to convert my measurements to inches or centimeters first?
Not at all. Our calculator allows you to use different units for each measurement and will even convert existing values for you if you change the unit. You can even mix-and-match different units. It is designed to work without any manual conversions on your part.
Does this calculator find the actual water volume or the total tank volume?
This is an excellent and critical question. Our tool is designed to give you both in two distinct sections:
- The main "Calculate" section finds the Total Tank Volume, the full capacity of your aquarium if it were filled to the very top. This is the number you need for choosing heaters and filters.
- The "Water Fill" section calculates the Water Volume based on a specific fill height. This is perfect for knowing exactly how many gallons or liters you're adding during a water change or when first setting up your tank. You can use this to offset for displacements by substrate as well.