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20 Gallon Long Aquarium Dimensions

Standard 20-gallon long tank dimensions, filled weight, and stand notes.

MeasurementValue
Nominal size20 gallon long
Dimensions (L × W × H)30 × 12 × 12 in
Approx. filled weight≈ 225 lb
Common usesSame volume as a 20 gallon High but longer and shallower -- generally the better stocking footprint, and a favorite for planted low-tech setups.

Nominal vs. actual dimensions

Tank dimensions are generally accurate to the glass, but always double-check against your specific manufacturer, since trim, rim style, and glass thickness can shift the outer dimensions by a small margin. Filled weight includes the tank, water, substrate, and decor -- confirm your stand and floor can support it before filling.

Source: Standard, widely-used US aquarium industry dimensions for this tank size.

Frequently asked questions

Are these dimensions exact for every brand?

They're standard for this size, but always confirm against your specific tank's manufacturer, since trim and rim style can vary slightly between brands.

Does filled weight include the stand?

No -- this is the tank itself, filled with water, substrate, and decor. Check your stand's own weight rating separately, and see our Stand & Floor Load Calculator for a fuller picture.

Can I use a smaller stand than this tank's footprint?

Not recommended -- a stand should fully support the tank's footprint; an undersized stand risks instability, especially once the tank is filled and heavy.

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