How Big Is a 10-Gallon Fish Tank? Dimensions by Maker

Each size in the table is the maker’s own, for the model named. For empty and filled weights, see our guide to how much a 10-gallon tank weighs.

10-gallon tanks, maker by maker

Maker and model	Listed size (in)	In cm (our conversion)
Aqueon 10 Leader, glass	20¼ x 10½ x 12 9/16	51.4 x 26.7 x 31.9
Tetra Complete LED Kit 10, glass	20 x 10 x 12 (approximate)	50.8 x 25.4 x 30.5 (approximate)
Marineland 10 Gallon Glass Aquarium Kit	15.125 x 15.2 x 13.125	38.4 x 38.6 x 33.3
TruVu 10 Gallon, acrylic	20 x 10 x 12	50.8 x 25.4 x 30.5

• Aqueon’s sizing chart lists tanks as L x W x H, with a drawing of “How the aquarium is measured”.
• Marineland’s page (another aquarium maker; it and Tetra are both Spectrum Brands) lists “10-gallon (15.125” x 15.2” x 13.125”)” without saying which figure is which; its dimension photo marks 15.125 inches across the front, 15.2 front to back and 13.125 high.
• Fluval’s Flex kit, the nearest Fluval size we found, holds “9 US Gal / 34 L” at “14″ L x 13″ W x 13″ H / 35 x 33 x 33 cm”.

The whole-number 20 x 10 x 12 is what Top Shelf Aquatics, a reef retailer, prints: “10 gallon (20 × 10 × 12 in)”, which it calls “nominal dimensions”.

Footprint and stand space

Footprints (length x width) come to about 213 square inches for Aqueon’s 10 Leader, 200 for the 20 x 10 tanks and about 230 for Marineland’s kit (our arithmetic). Each maker’s placement wording:

• Aqueon’s sizing chart: “For safety reasons, and to fulfill warranty requirements, it is essential to place your aquarium on an appropriately sized, suitably designed aquarium stand, which will meet all weight and safety specifications.”
• Aqueon’s setup article: “Make sure the stand is level and does not rock or wobble. Use wood shims to level and stabilize the stand if necessary.”
• Tetra’s kit setup guide: “Pick a flat, level surface near an electrical outlet. An aquarium stand is recommended.”
• Tetra’s tank warranty, issued by Spectrum Brands for Tetra brand tanks (the copy we read is on PetSmart’s site), is void in two stand cases: “If the Aquarium Tank Product is placed on any surface that is not commercially manufactured for use with an aquarium of the Aquarium Tank Product’s size and weight or is inadequate to accommodate the size and weight of the Aquarium Tank Product.” and “If the Aquarium Tank Product is placed on a stand, surface, or structure that does not provide a flat, level surface capable of fully supporting the Aquarium Tank Product and its contents, such as on shelving, book cases, dressers, television sets, tables, or carts.”

Top Shelf adds: “Always measure your own tank before buying a stand or lid, and confirm volume with the aquarium volume calculator.” Our fish tank set-up guide covers choosing a level spot and a stand made for the tank; for a tank already set up, see our guide to moving a fish tank.

Standard, long, tall and near-square shapes

Top Shelf says of its chart: “Use it to compare footprints before you buy, since two tanks with the same gallon rating can have very different dimensions and stands.” Aqueon’s chart has one 10-gallon row. hygger, an equipment brand, lists three 10-gallon shapes without naming models: standard 20 x 10 x 12, long 24 x 8 x 12 and tall 16 x 10 x 18 inches. On the 231 divisor below, the tall box comes to about 12.5 gallons (our arithmetic). Marineland’s kit is nearly square in footprint (our reading). Our guide to fish for a 10-gallon tank lists 13 species that sources recommend.

Glass or acrylic

Aqueon’s standard tanks have “High quality glass construction”, Tetra calls its kit a “10-gallon glass tank”, and Marineland’s is a “Glass Aquarium Kit”. Neither Aqueon’s chart nor Tetra’s kit page gives a glass thickness. TruVu, an acrylic aquarium maker, gives its tank the same 20 x 10 x 12 inch outline as Tetra’s kit, with “1/4 in. Body – 1/4 in. Top/Btm”.

Dr. Jessie Sanders, an aquatic veterinarian at Aquatic Veterinary Services, on cleaning: “It is critical that you use a scrubber that is appropriate for your tank type. Glass scrubs are more abrasive and can scratch acrylic, causing a hazy appearance. If you are unsure, it is better to choose one for acrylic.”

Drilling. Aqueon’s chart says “tempered-bottom aquariums are exceptionally strong but cannot be drilled”; it does not say which sizes are tempered-bottom. Tetra’s warranty is void if the tank has had “any modification or alteration including by drilling, cutting, sawing, gluing anything to, bending, melting, taping, or other similar means”. TruVu’s acrylic tank comes with a “Filter slot” and “2 – Heater holes”.

Gallons on the label vs water in the tank

A U.S. gallon is 231 cubic inches (our arithmetic from conversion factors published by NIST, the federal standards agency), so a box’s gallons are length x width x height in inches, divided by 231. Top Shelf uses the same divisor: “For example, 48 by 18 by 21 inches is 18,144 cubic inches divided by 231, or about 78 gallons, which is sold as a 75.”

On the listed figures, Tetra’s 20 x 10 x 12 comes to about 10.4 gallons, Aqueon’s 10 Leader to about 11.6 and Marineland’s kit to about 13.1 (our arithmetic). A box measured outside includes the glass and any frame or base, so it overstates the water (our reading). For Marineland’s kit the gap is larger than glass alone explains (our reading); its page does not say why. The makers’ own words:

• TruVu gives “Actual Gallons 9.25” for its 20 x 10 x 12 inch acrylic tank; its page does not say how it measured it.
• Glass Cages, a custom aquarium builder, on its acrylic tank list: “Gallonage is an estimate. For actual aquarium sizes please go by their listed dimensions.”
• Tetra’s setup guide fills in two stages: first “to within two to three inches of the aquarium rim”, then “Water line should be just above the bottom of the aquarium frame, hidden from view.”

Ten U.S. gallons is about 37.9 liters (our conversion, NIST factors).

Measuring your own tank. For a stand, lid or shelf, use the outside length and width; Top Shelf says to “measure your own tank before buying a stand or lid”. Dividing outside inches by 231 gives a box volume that reads above the label (10.4 to 11.6 gallons for the two 10-gallon glass tanks above, our arithmetic), so a result a little over the label does not make it a larger size. Glass Cages says, for its own tanks, to “go by their listed dimensions”.

Frequently Asked Questions

Aqueon, a tank maker, says bigger tanks are “easier to take care of and are far more forgiving of beginner mistakes”, and advises readers to “buy the largest aquarium that meets your needs” (the page is about tank size in general and does not mention 10 gallons).

Aqueon makes two 20-gallon shapes: the 20 High at 24¼ x 12½ x 16¾ inches and the 20 Long at 30¼ x 12½ x 12¾. Its 5½ is 16 3/16 x 8⅜ x 10½, and its 15 is 24¼ x 12½ x 12¾ (the chart also has a 15 Column, 13¾ x 13⅝ x 25).

Aqueon’s chart has neither. Its nearest rows are the 90 at 48½ x 18½ x 25⅛ inches and the 210 at 72½ x 24½ x 29⅝.

The two kits we read do: Tetra’s has “a low-profile, hinged hood with white LED lights”, and Marineland’s a “Sliding glass canopy for easy access”. Aqueon’s 10 Leader is listed as a tank on its sizing chart, which mentions no lid.

Sources (15)

• Aqueon, aquarium sizing chart (PDF) (maker)
• Aqueon, Standard Glass Rectangle Aquariums (maker)
• Aqueon, Setting Up a Freshwater Aquarium (maker)
• Aqueon, Choosing the Right Aquarium (maker)
• Tetra, Complete LED Aquarium Kit 10 Gal (maker)
• Tetra, Aquarium Kit Set-Up Guide (PDF) (maker)
• Tetra tank Limited Warranty, Spectrum Brands (PDF, PetSmart copy) (maker document)
• Marineland, 10 Gallon Glass Aquarium Kit (maker)
• Fluval, Flex Aquarium Kit, 9 US Gal (maker)
• TruVu Aquariums, 10 Gallon Acrylic 20x10x12 (maker)
• Glass Cages, Acrylic Aquariums (aquarium builder)
• Aquatic Veterinary Services, How to Clean a Fish Tank (veterinary practice)
• NIST, SP 811 Appendix B.9 (federal agency)
• hygger, How Many Fish in a 10-Gallon Tank (equipment brand blog)
• Top Shelf Aquatics, Aquarium Size Calculator (retailer)