A Cheat Sheet to Fish Tank Gallon Sizes and Dimensions

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Fish Tank Measurements With Standard Shapes

Firstly I will be listing the dimensions and gallon capacities of the most popular aquariums with a standard rectangular shape.

After that, I will list the branded tanks with irregular shapes and sizes.

Here are the dimensions and gallon sizes of all standard fish tanks:

Small Standard Aquariums

You’d want to avoid getting a small tank if you’re a complete beginner in fish keeping.

Smaller tanks get polluted the quickest and it’s more difficult for a beginner to keep the water parameters in check.

Tank Size Dimensions in Inches
L x W x H
Aquarium Shape
2.5 Gallon 12.25 x 6.25 x 8.125 Standard Rectangular
5 Gallon 16 x 8 x 10 Standard Rectangular
5.5 Gallon 16.25 x 8.375 x 10.5 Standard Rectangular
10 Gallon Leader 20.25 x 10.5 x 12.6 Standard Rectangular
10 Gallon Long 24.25 x 8.5 x 12.6 Standard Rectangular
15 Gallon 24.5 x 12.5 x 12.75 Standard Rectangular
15 Gallon Tall 20.25 x 10.5 x 18.75 Standard Rectangular
15 Gallon Show 24.25 x 8.5 x 16.6 Standard Rectangular

Mid-Sized Standard Aquariums

If you’re a fish keeping beginner you’d want to start with a mid-sized tank as it’d be easier to manage.

I realize we all may have space and budget constraints but if you have the means to – go for a middle-sized aquarium.

Tank Size Dimensions in Inches
L x W x H
Aquarium Shape
20 Gallon Tall 24.25 x 12.5 x 16.75 Standard Rectangular
20 Gallon Long 30.25 x 12.5 x 12.75 Standard Rectangular
20 Gallon Extra Tall 20.25 x 10.5 x 23.75 Standard Rectangular
23 Gallon Long 36.25 x 12.625 x 13 Standard Rectangular
25 Gallon 24.25 x 12.5 x 20.75 Standard Rectangular
29 Gallon 30.25 x 12.5 x 18.75 Standard Rectangular
30 Gallon 36.25 x 12.625 x 16.75 Standard Rectangular
30 Gallon Breeder 36.25 x 18.25 x 13 Standard Rectangular
30 Gallon Extra Tall 24.25 x 12.5 x 24.75 Standard Rectangular
33 Gallon Long 48.25 x 12.75 x 13.375 Standard Rectangular
37 Gallon 30.25 x 12.5 x 22.75 Standard Rectangular
38 Gallon 36.25 x 12.625 x 19.75 Standard Rectangular
40 Gallon Breeder 36.25 x 18.25 x 17 Standard Rectangular
40 Gallon Long 48.25 x 12.75 x 16.875 Standard Rectangular
45 Gallon 36.5 x 12.625 x 23.75 Standard Rectangular
45 Gallon Long 48.25 x 12.75 x 19 Standard Rectangular

Large Standard Aquariums

Large tanks can be very rewarding if you do your homework.

Nothing compares to having a big ecosystem with lots of small schooling fish, turtles or monster fish at home.

Larger aquariums are also the most stable in terms of water parameters.

Tank Size Dimensions in Inches
L x W x H
Aquarium Shape
50 Gallon 36.375 x 18.375 x 19 Standard Rectangular
55 Gallon 48.25 x 12.75 x 21 Standard Rectangular
60 Gallon 48.375 x 12.875 x 23.875 Standard Rectangular
65 Gallon 36.375 x 18.375 x 25 Standard Rectangular
75 Gallon 48.5 x 18.5 x 21.25 Standard Rectangular
80 Gallon Extra Tall 48.875 x 14 x 30.75 Standard Rectangular
90 Gallon 48.5 x 18.5 x 24.375 Standard Rectangular
100 Gallon 72.5 x 18.5 x 19.375 Standard Rectangular
110 Gallon Extra Tall 48.875 x 19 x 30.75 Standard Rectangular
120 Gallon 48.5 x 24.5 x 25.5 Standard Rectangular
125 Gallon 72.5 x 18.5 x 21 Standard Rectangular
150 Gallon 72.5 x 18.5 x 29.5 Standard Rectangular
180 Gallon 72.5 x 24.5 x 25.625 Standard Rectangular
210 Gallon 72.5 x 24.5 x 29.625 Standard Rectangular
225 Gallon 72.5 x 27.5 x 27.5 Standard Rectangular

Measurements of Brand Fish Tanks With Irregular Shapes and Sizes

Branded tanks don’t follow any rules about dimensions or gallon capacities.

They are mostly unique and the brand that makes the tank decides what its measurements would be.

Here are the dimensions of all irregularly-shaped aquarium kits:

Small Branded Aquariums

Starting with the dimensions of the smallest branded tanks, this is probably the longest chart in this list.

That’s because many brands recognize that small tanks are the biggest revenue drivers (which is not a good thing, since as I said earlier, beginners should ideally start with a mid-sized tank).

Aquarium Kit Dimensions in Inches L x W x H Shape
0.5 Gallon Penn Plax Aqua-ponic 5.875 x 5.875 x 8 Cylinder
1 Gallon Aqueon Frameless 6.375 x 6.375 x 6.375 Cube
1 Gallon Koller Kit 7.5 x 10.5 x 10.2 Pentagon
1 Gallon Koller Hex 7.8 x 7.8 x 8 Hexagon
1 Gallon Koller BettaTank 9 x 9 x 10 Bowl
1 Gallon Koller Deco 15 x 3.8 x 8.5 Half Circle
1 Gallon Aqueon MiniBow LED Kit 8.5 x 6.25 x 9.25 Bow Front
1.4 Gallon Penn Plax Aqua-ponic 7.875 x 7.875 x 10 Cylinder
1.5 Gallon Tetra LED Cube Kit 8.00 x 8.20 x 10.20 Cube
1.5 Gallon Tetra GloFish Kit 7.25 x 8.5 x 11.5 Cube
1.5 Gallon Koller AquaScene 8.5 x 8.5 x 9 Cube
1.5 Gallon Koller BettaView 360 8.1 x 8.1 x 9.8 Cylinder
1.5 Gallon Koller AquaView 9 x 8.2 x 10.8 Half Cylinder
1.5 Gallon Penn Plax Betta Fish Kit 8.5 x 6 x 9.5 Rectangular
1.6 Gallon Koller BettaTank Pedestal 9.5 x 9.5 x 9.5 Bowl
1.7 Gallon Koller BettaTank 9.5 x 9.5 x 11 Bowl
1.7 Gallon Koller AquaScene 8.4 x 8.4 x 11 Hexagon
1.8 Gallon Tetra Waterfall Globe 12 x 10.75 x 13.5 Bowl
2 Gallon Fluval Spec 7.25 x 9.25 x 10 Rectangular
2 Gallon Koller Hex 9.2 x 9.2 x 9.2 Hexagon
2 Gallon Koller AquaView 360 10.2 x 10.2 x 10.5 Cylinder
2 Gallon Koller Gumball 8.5 x 8.5 x 10 Bowl
2 Gallon Penn Plax Prism Nano 7 x 10 x 9 Rectangular
2.5 Gallon Koller AquaView 9.5 x 9.5 x 11.2 Pentagon
2.5 Gallon Koller AquaTunes 9.5 x 9.5 x 11.2 Pentagon
2.5 Gallon Koller AquaTunes 9.5 x 9.5 x 11.2 Cube
2.5 Gallon Aqueon BettaBow LED Kit 11.5 x 7.63 x 12.5 Bow Front
2.5 Gallon Aqueon MiniBow LED Kit 11.5 x 7.63 x 12.5 Bow Front
2.6 Gallon Fluval Spec 10.8 x 11.8 x 8.7 Rectangular
2.65 Gallon Marina 360 10 x 10 x 10 Cylinder
2.7 Gallon Penn Plax Vertex 10 x 9 x 7.75 Cube
3 Gallon Tetra LED Cube Kit 10.3 x 11 x 17.5 Cube
3 Gallon Marineland Silhouette 14.2 x 13.7 x 12.3 Rectangular
3 Gallon Tetra GloFish Kit 14.6 x 8.8 x 11.2 Rectangular
3 Gallon Tetra ColorFusion Half Moon 12.9 x 6.8 x 12.5 Half Cylinder
3 Gallon Marineland Contour Desktop 9.63 x 9.63 x 14 Cube
3 Gallon Tetra Bubbling Half Moon 12.9 x 6.8 x 12.5 Half Cylinder
3 Gallon Tetra GloFish Half Moon 7.5 x 7.5 x 7.7 Half Cylinder
3 Gallon Tetra GloFish Crescent 13 x 7 x 9.5 Bow Front
3 Gallon Aqueon Frameless 9.25 x 9.25 x 9.25 Cube
3 Gallon Koller AquaView 360 10.2 x 10.2 x 14.5 Cylinder
3 Gallon Koller AquaView 14.5 x 10 x 9.2 Flat Back Hexagon
3 Gallon Koller AquaTunes 12.8 x 11.8 x 9 Cylinder
3 Gallon Koller AquaView 11.5 x 11 x 11 Bowl
3 Gallon Marineland Nook Kit 13 x 7.1 x 9.3 Bow Front
3.4 Gallon Penn Plax Water World 10.25 x 7.75 x 11 Rectangular
3.5 Gallon Koller AquaView 11.2 x 8.8 x 13.5 Half Cylinder
3.5 Gallon Koller AquaTunes 11.2 x 8.8 x 13.5 Half Cylinder
3.5 Gallon Koller 11.2 x 8.8 x 13.5 Half Cylinder
4 Gallon biOrb Classic 11.75 x 11.75 x 12.5 Bowl
4 Gallon biOrb Flow 8.19 x 11.81 x 12.4 Rectangular
4 Gallon biOrb Halo 11.81 x 11.81 x 13 Bowl
4 Gallon biOrb Life 11.41 x 7.6 x 16 Rectangular
4 Gallon biOrb Tube 12.91 x 12.91 x 12.4 Cylinder
4.5 Gallon Koller AquaView 14.8 x 10.8 x 13.2 Double Bullnose
5 Gallon Marineland Portrait 11.8 x 11.6 x 17 Cube
5 Gallon Marineland Contour Desktop 9.6 x 9.6 x 19 Cube
5 Gallon Tetra Crescent 16.5 x 11.25 x 13.2 Bow Front
5 Gallon Tetra ColorFusion Bubbling 16 x 8 x 10 Rectangular
5 Gallon Tetra GloFish Glass 16 x 8 x 10 Rectangular
5 Gallon Tetra GloFish Crescent 15.5 x 9 x 11.5 Bow Front
5 Gallon Fluval Chi 10 x 10 x 14.4 Rectangular
5 Gallon Fluval Spec 20.5 x 11.6 x 7.5 Rectangular
5 Gallon Fluval EVO 20.5 x 11.6 x 7.5 Rectangular
5 Gallon Marina Kit 18.5 x 10.8 x 13.3 Rectangular
5 Gallon Koller PanaView 14.2 x 11.5 x 10 Round-edge Rectangular
5 Gallon Aqueon MiniBow LED Kit 14.5 x 10 x 13.5 Bow Front
5 Gallon Aqueon NeoGlow 11.438 x 11.31 x 14.813 Cube
5 Gallon Marineland Nook Kit 15.2 x 5 x 11.25 Bow Front
5 Gallon Marineland Escape 5 14 x 12.5 x 13.5 Hexagon
5 Gallon Penn Plax Water World 13.75 x 8.75 x 11 Rectangular
5 Gallon Penn Plax Vertex 12 x 10.5 x 9.75 Cube
5.5 Gallon Aqueon NeoGlow 16.5 x 8.75 x 10.5 Rectangular
6 Gallon Aqueon Frameless 11.5 x 11.5 x 11.5 Cube
6 Gallon Koller AquaView 360 11 x 11 x 19.8 Cylinder
6 Gallon Aqueon Ascent Frameless 16 x 8.125 x 13.5 Rectangular
6 Gallon Fluval Edge 16.9 x 10.25 x 14 Rectangular
6.5 Gallon Koller 18 x 11 x 13.5 Flat Back Hexagon
7 Gallon Koller AquaView 18.25 x 12.38 x 13.10 Bow Front
7.5 Gallon Aqueon NeoGlow 14.813 x 14 x 13.813 Cube
7.5 Gallon Aqueon Shrimp Kit 13 x 12 x 14 Cube
8 Gallon Aqueon NeoGlow 15 x 13 x 15.25 Hexagon
8 Gallon biOrb Classic 15.75 x 15.75 x 16.5 Bowl
8 Gallon biOrb Cube 12.6 x 12.6 x 13.6 Cube
8 Gallon biOrb Flow 10.23 x 14.96 x 15.35 Rectangular
8 Gallon biOrb Halo 15.75 x 15.75 x 18.11 Bowl
8 Gallon biOrb Life 15.75 x 9.25 x 16.54 Rectangular
8 Gallon biOrb Tube 12.91 x 12.91 x 20.2 Cylinder
8.75 Gallon Aqueon Shrimp Kit 18.25 x 12 x 13 Rectangular
8.8 Gallon Aqueon Aqua Springs 15 x 15 x 14.75 Cube
9 Gallon Fluval Flex 14 x 13 x 13 Vertical Bow Front
9 Gallon biOrb Tube 16.14 x 16.14 x 14.53 Cylinder
10 Gallon Marineland BIO Wheel 20 x 10 x 12 Rectangular
10 Gallon Tetra ColorFusion Bubbling 20 x 10 x 12 Rectangular
10 Gallon Tetra PLAYMOBIL 20 x 10 x 13 Rectangular
10 Gallon Tetra Complete LED 20 x 10 x 12 Rectangular
10 Gallon Tetra Goldfish 20 x 10 x 12 Rectangular
10 Gallon Tetra Half Moon 17.75 x 11 x 17 Half Cylinder
10 Gallon Tetra GloFish Glass 20 x 10 x 12 Rectangular
10 Gallon Aqueon Glass 14.5 x 12.625 x 18.375 Hexagon
10 Gallon Marina Kit 22.6 x 12.6 x 15.3 Rectangular
10 Gallon NUVO Fusion Pro 11.8 x 15 x 13 Cube
10 Gallon Aqueon 20.25 x 10.5 x 15 Rectangular
10 Gallon Aqueon Ascent Frameless 18.75 x 10 x 15.75 Rectangular
10 Gallon Aqueon Hexagon LED Kit 14.5 x 13.375 x 14.75 Hexagon
10 Gallon Aqueon Incandescent LED Kit 22.88 x 12.75 x 13.88 Rectangular
10 Gallon Aqueon NeoGlow 20.5 x 10.5 x 12.5 Rectangular
10 Gallon Penn Plax Water World 17.75 x 11.75 x 12.63 Rectangular
10 Gallon Penn Plax Vertex 13.75 x 13.75 x 13.75 Cube
11 Gallon Aqueon Framless 20.25 x 10.5 x 12.625 Rectangular
11 Gallon Aqueon Frameless 20.25 x 10.5 x 12.625 Rectangular
11 Gallon Aqueon Aqua Springs 15 x 15 x 17.75 Cube
12 Gallon Fluval Edge 17.5 x 10.25 x 22.9 Cube
12 Gallon biOrb Life 14.76 x 10 x 22.04 Rectangular
13.5 Gallon Fluval EVO 22 x 15 x 11.5 Rectangular
14 Gallon Aqueon Frameless 15.125 x 15.125 x 15.125 Cube
14 Gallon NUVO Fusion Pro Peninsula 11.8 x 20 x 13 Rectangular
14.5 Gallon Fluval Flora 15 x 15 x15 Cube
15 Gallon Fuval Flex 16 x 15 x 15 Vertical Bow Front
15 Gallon SeaClear Deluxe 15 x 15 x 20 Hexagon
15 Gallon Aqueon Column 13.75 x 13.75 x 25 Cube
16 Gallon Aqueon 20.25 x 12.875 x 17.75 Bow Front
16 Gallon Fluval Spec 21.8 x 11.5 x 17.5 Rectangular
16 Gallon Aqueon Bow Front LED Kit 20.25 x 12.875 x 20.5 Bow Front
16 Gallon biOrb Classic 19.75 x 19.75 x 20.5 Bowl
16 Gallon biOrb Cube 15.75 x 15.75 x 17 Cube
16 Gallon biOrb Halo 19.66 x 19.66 x 22.83 Bowl
16 Gallon biOrb Life 16.54 x 11 x 24.4 Rectangular

Mid-Sized Branded Aquariums

The mid-sized branded tanks can also be good for starters in the hobby, as long as they are not too weirdly-shaped.

Aquarium Kit Dimensions in Inches L x W x H Shape
20 Gallon Marineland BIO Wheel 24 x 12 x 16 Rectangular
20 Gallon Tetra Complete LED 24 x 12 x 16 Rectangular
20 Gallon Tetra Goldfish 24 x 12 x 16 Rectangular
20 Gallon Aqueon Glass 18.75 x 16.25 x 20.625 Hexagon
20 Gallon SeaClear Deluxe 15 x 15 x 24 Hexagon
20 Gallon SeaClear 24 x 13 x 16 Rectangular
20 Gallon Marina Kit 26.3 x 15 x 19 Rectangular
20 Gallon NUVO Fusion Pro 23.62 x 15 x 13 Rectangular
20 Gallon NUVO Fusion Pro Peninsula 11.8 x 30 x 13 Rectangular
20 Gallon NUVO Concept Pro Peninsula 15 x 20 x 13 Drop Off Rectangular
20 Gallon NUVO Concept Pro 20 x 15 x 13 Drop Off Rectangular
20 Gallon Aqueon Ascent Frameless 23.75 x 12.625 x 19.75 Rectangular
20 Gallon Aqueon Hexagon LED Kit 18.75 x 16.25 x 23 Hexagon
20 Gallon Marineland Half Moon Combo 23.5 x 12.12 x 23.45 Half Cylinder
21 Gallon Aqueon Framless 24.25 x 12.25 x 16.75 Rectangular
21 Gallon Aqueon Frameless 24.25 x 12.25 x 16.75 Rectangular
25 Gallon NUVO Fusion Pro Lagoon 23.62 x 19.68 x 11.8 Rectangular
25 Gallon NUVO EXT Lagoon 23.6 x 19.7 x 11.8 Cube
26 Gallon Aqueon 24.125 x 14.75 x 20.875 Bow Front
26 Gallon SeaClear 36 x 12 x 16 Flat Back Hexagon
26 Gallon Aqueon Bow Front LED Kit 24.125 x 14.75 x 23.625 Bow Front
28 Gallon Tetra Connect 24 x 15 x 18.9 Bow Front
28 Gallon biOrb Classic 24 x 24 x 25 Bowl
29 Gallon Marineland BIO Wheel 30.25 x 12.5 x 18.75 Rectangular
29 Gallon Tetra Complete LED 30 x 12 x 18 Rectangular
29 Gallon SeaClear 30 x 12 x 18 Rectangular
30 Gallon Aqueon Framless 30.25 x 12.5 x 18.75 Rectangular
30 Gallon SeaClear 36 x 12 x 16 Rectangular
30 Gallon NUVO Fusion Pro 35.43 x 14.96 x 12.99 Rectangular
30 Gallon NUVO EXT 35.4 x 15 x 13 Rectangular
30 Gallon Aqueon Frameless 30.25 x 12.5 x 18.75 Rectangular
30 Gallon Marineland Half Moon Combo 26.7 x 13.5 x 26.9 Half Cylinder
32.5 Gallon Fluval Flex 32.5 x 15.35 x 15.75 Vertical Bow Front
35 Gallon Aqueon Glass 23.25 x 20.25 x 24.75 Hexagon
35 Gallon Aqueon Hexagon LED Kit 23.25 x 20.25 x 27.125 Hexagon
36 Gallon Aqueon 30.25 x 15.5 x 20.875 Bow Front
36 Gallon Aqueon Bow Front LED Kit 30.25 x 15.5 x 23.625 Bow Front
40 Gallon SeaClear 36 x 12 x 16 Rectangular
40 Gallon NUVO Fusion Pro 23.62 x 19.68 x 18.89 Cube
45 Gallon NUVO EXT 23.6 x 19.7 x 18.9 Cube
46 Gallon Aqueon 36.375 x 16.375 x 20.875 Bow Front
46 Gallon SeaClear 36 x 16.25 x 20 Bow Front

Large Branded Aquariums

And finally, here are the dimensions of large branded tanks that have irregular shapes.

Aquarium Kit Dimensions in Inches L x W x H Shape
50 Gallon SeaClear 36 x 15 x 20 Rectangular
50 Gallon NUVO Fusion Pro Lagoon 29.92 x 23.62 x 16.14 Rectangular
50 Gallon NUVO EXT Lagoon 30 x 23.6 x 16.1 Rectangular
50 Gallon NUVO INT 23.6 x 23.6 x 19.7 Cube
54 Gallon Aqueon 39 x 27.25 x 23 Corner Bow Front
55 Gallon Marineland BIO Wheel 48.25 x 12.75 x 21 Rectangular
55 Gallon Tetra Complete LED 48 x 13 x 21 Rectangular
60 Gallon NUVO SR Pro 35.43 x 23.62 x 16.14 Rectangular
70 Gallon NUVO INT 23.6 x 35.4 x 55 Drop Off Rectangular
72 Gallon Aqueon 48.375 x 18 x 23 Bow Front
75 Gallon NUVO EXT 35.4 x 23.6 x 19.7 Rectangular
75 Gallon NUVO INT 35.4 x 23.6 x 19.7 Rectangular
90 Gallon NUVO SR Pro 47.24 x 23.62 x 16.14 Rectangular
100 Gallon NUVO EXT 47.3 x 23.6 x 19.7 Rectangular
100 Gallon NUVO INT 47.3 x 23.6 x 19.7 Rectangular
112 Gallon NUVO INT Lagoon 35.4 x 35.4 x 19.7 Cube
150 Gallon NUVO INT Lagoon 47.3 x 35.4 x 19.7 Rectangular
200 Gallon NUVO INT 70.9 x 30 x 21.7 Rectangular
200 Gallon NUVO EXT 70.9 x 30 x 21.7 Rectangular

How to Calculate the Weight of Your Aquarium?

To calculate the total weight of an aquarium you’d want to first figure out how much it weighs empty.

After that, you calculate the water weight and then add the two together. To find out how much your tank weighs follow these steps:

  1. Calculate the surface area of the fish tank.

    To find the total surface area of your tank you’d need to find the surface areas of each of its walls, including the bottom, and add them together.

    The surface area of each rectangular flat surface is calculated by multiplying its sides.

    So if your tank’s wall measures 10 x 20 inches, then you multiply that and get that the surface area of that wall is 200 square inches.

    Do this for each of the tank’s flat surfaces and add them together.

    The formula for finding the surface area for a standard rectangular tank is:

    (2 × length × height) for the sides + (2 × width × height) for the other two sides + (width × length) for the bottom.

    Bowfront tanks are an exception to this formula because they have a curved wall which is almost impossible to calculate on your own at home.

  2. Calculate the empty weight of your tank.

    To calculate the empty weight of a tank you’d want to multiply its total surface area by the thickness of the walls.

    The material your tank is made of plays a role here since different materials have different weights.

    Typically aquariums are made of acrylic or glass. Glass weighs roughly 0.5165 pounds per square foot for each millimeter of thickness.

    Acrylic weighs approximately 0.24 pounds per square foot for each millimeter of thickness.

    Measure the thickness of the tank’s walls in millimeters and write that down.

    To proceed with calculating the tank’s empty weight you’d want to convert the square inches of total surface area we found in step 1 into square feet.

    This is easily done by dividing the total square inches by 144 since there are 144 sq inches in an sq foot.

    After you convert the surface area of the fish tank in square feet multiply that by the thickness of the glass in millimeters and the specific weight of the material.

    The formula looks like this:

    Tank Surface Area in Square Feet × Thickness of the Wall in mm × Specific Material Weight.

    For example, if your tank has 7 square feet of surface area, with a wall thickness of 10 mm, and is made of glass the calculation would be 7 × 10 × 0.5165 = 36.155 pounds of empty weight.

  3. Calculate the gallon capacity of the tank.

    All tanks that you buy from the store will have a label clearly stating how much water they can hold.

    However, if you get a second-hand tank or have just forgotten what it was there is a way to calculate that.

    You simply need to convert the tank’s height, length, and width from inches to feet, then multiply them to find out the volume in inches.

    Turn that into cubic feet and multiply the result by 7.48. To convert the cubic inches into cubic feet you need to divide the volume by 1728.

    If this seems counterintuitive thank the Imperial unit system.

    Taking this into account you can use the following formula to calculate the gallon capacity of your tank:

    (Lenght × Width × Height, all in inches) ÷ 1728 x 7.48

    So if you have a tank that measures 10 × 20 × 15 inches and you’re going to fill it with fresh water, then the calculation would look like this:

    ((10 × 20 × 15) ÷ 1728) × 7.48 = roughly 13 gallons.

  4. Calculate the filled weight of the tank.

    To do so you’d want to first find the weight of water and then add that up to the empty tank weight.

    To calculate the weight of water:

    Multiply the gallon capacity of your tank, which we found in step 3 by how much water weighs per pound.

    Freshwater and saltwater have different weights because of their different density.

    Freshwater weighs 8.345 pounds per gallon. Saltwater is heavier and weighs about 8.554 pounds per gallon.

    So if your tank can hold 20 gallons and you want to fill it with freshwater then multiply 20 × 8.345 = 166.9 pounds.

    Now add that up to the tank’s empty weight (calculated in step 2) and you’d find the total weight of your tank when it’s filled to the brim with water.

I provided all the formulas so that anyone with a non-standard tank can figure it out on their own.

For a generic weight estimate of standard tanks you can use a fish tank weight calculator like this one.

Getting equipment according to the dimensions of the aquarium?

Selecting aquarium equipment based on the size of the tank is essential for its long-term success.

Lighting

The dimensions of a fish tank play a huge role in the choice of aquarium lighting because light itself has a limited water penetration.
aquarium lighting

by tomas10024

If you’re in the middle of your research on choosing a suitable light fixture for your aquarium plants you can check my guide on that here.

In that link, I do specific product recommendations based on aquarium depth and the type of plants you may want to keep.

The same rules apply for picking adequate grow lights for saltwater reef aquariums.

Corals are very sensitive to the intensity and spectrum of the incoming light they use for photosynthesis.

To end up with the right LED light you’ll need to take into account the dimensions of your coral reef aquarium.

There are stronger units that penetrate the water well and are suitable for deeper reef tanks and others that are less intense, making a good addition to aquariums with less demanding corals.

I made specific recommendations on choosing the best LED lights for corals based on aquarium height and the species you want to keep. Visit the link to learn more.

Filter

Choosing the flow rate of a water filter should also be made in conjunction with the gallon capacity of the fish tank.

If you keep larger carnivorous fish that produce more waste or you plan to overstock the tank you’d want a stronger filter that turns the water at least 6 times per hour.

For Oscar or Cichlid fish tanks getting an external canister filter makes perfect sense as these units produce more flow and have enormous space for media, which in turn keeps the aquarium clean and safe.

I have an article on choosing one according to your aquarium’s gallon capacity (visit the link to learn how to make a choice).

If you want to keep aquatic turtles you should still take into consideration the available water volume in the aquarium.

In this case, you can check my article on picking a good filter for a turtle aquarium according to gallon capacity.

Turtles are messier than most aquatic pets and require a water turn over of at least 8 times the whole aquarium’s gallon capacity per hour.
turtle tank

by turtleuwu69

Heater

A small 3-gallon, 5-gallon, or 10-gallon tank with tropical fish requires a small-sized aquarium heater that’s ideally under 6.5 inches in length.

I’ve seen enough small aquariums with a spoiled interior because the owner got an over-sized heater.

Wavemaker

Last but not least, the gallon capacity of your reef tank, for example, plays a major role in your choice of aquarium wavemaker.

You can check my guide on how to make the correct choice by clicking here.

Knowing the exact dimensions of your new fish tank will give you the needed information to make adequate decisions on choosing livestock and the purchase of equipment.

Drop me a comment below if you have any questions in those areas and I will answer as soon as I see it.

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13 thoughts on “A Cheat Sheet to Fish Tank Gallon Sizes and Dimensions”

  1. Great article! Wondering if you could help me with finding a gallon size of a 36” L x 12”D x 16”H flat back hexagon? Maybe a lid for it too

  2. Where can I get a 30 Gallon Extra Tall?

    • Good question.

      They are not very common so your best chance would be online.

  3. I have been looking high and low for a air pump that will be sufficient for my needs but is quiet and doesn’t get hot. Would like to know if the Fluval Q2 is a good choice and if it will be strong enough to run several 18″ air bars in the bottom of my soon to be standard size 120 gallon. I will be upgrading and I haven’t even be able to find one strong enough for my 55 gallon. Any help would be great.

  4. Have a 10inches in height 10inches in width and 12inches dept dont know what gallon it is? Help

    • Hi, that would be a 5-gallon tank.

      The formula is as follows:

      10 inches = 0.83 Feet
      12 inches = 1 Foot

      (Lenght x Width x Depth) in feet = 0.6889 Cubic Feet.
      Cubic ft x 7.47 = 5.15 Gallons.

  5. I have an aquarium that is 48″x 12″ x 31″ which is about 75 gallons. I am just wondering if you might know who it is made by? I can’t find any information about a tank with these dimensions.
    Thank you.

  6. My tank is a 30×12×12 is that consider a 20 gallon

    • In my calculations, that’s a little over 18 gallons.

  7. I don’t have the slightest idea of where to begin with this tank! This is all new to me. From your cheat sheet I am guessing I have a 29 gallon tank. I’m confused though as to which 29 gallon tank I have because you have different types of tanks listed. The tank was given to me. Once I figure this part out then maybe I can figure out where to go from there lol. Help please!

    • Hi Denise,

      Could you measure its dimensions? This will help in figuring out which one you have.

      From there on, you just need to equip it with the right filter / lighting according to the tank’s size and the setup you’d want to achieve (e.g. heavily planted, non-planted, lots of fish, etc.).

      Best,
      Momchil

  8. Great information! Thank you for the article.

    • Thank you TKP!

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