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30 Gallon Tank Dimensions
A standard 30 gallon tank is about 36 × 12 × 16 in (91 × 30 × 41 cm) on the outside, holds about 25 gallons (96 litres) of water once set up, and weighs about 300 lb (135 kg) filled. Exact sizes vary by brand: Aqueon lists 36¼ × 12⅝ × 16¾ in and Marineland 36¼ × 129⁄16 × 16⅞ in. The water and weight figures assume 2 inches of sand and water 1 inch below the rim.
- How long is a 30 gallon tank? About 36 in (91 cm). Aqueon: 36¼ in; Marineland: 36¼ in.
- How tall is a 30 gallon tank? About 16 in (41 cm). Aqueon: 16¾ in; Marineland: 16⅞ in.
- How wide (front to back) is a 30 gallon tank? About 12 in (30 cm). Aqueon: 12⅝ in; Marineland: 12 9/16 in.
- How much does a 30 gallon tank weigh? About 43 lb empty (Aqueon; Marineland 41 lb) and about 304 lb set up with water and 2 in of sand, on 3.2 sq ft of floor. Add your stand and rock.
- How much gravel or sand for a 30 gallon tank? About 50 lb of sand or 40 lb of gravel for a 2 in bed. Work out other depths and bags.
- Is a 30 the same length as a 29 gallon? No: a 30 is about 36 in long, a 29 about 30 in.
30 gallon tank calculator
Drawn to scale from your numbers: sand at the bottom, water up to your fill line.
Equipment for a 30
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Setting up a 30?
- Plan your fish: the stocking calculator checks numbers and tank mates
- Size your heater for your room temperature and lid
- Work out your gravel or sand in pounds, litres and bags
- Check another tank's volume, any shape
Not every 30 gallon is the same size
The “30 gallon” label is a class of tank, not an exact measurement. Here is what each source actually lists:
| Source | L × W × H (in) | Empty | Full |
|---|---|---|---|
| Aqueon size chart (30) | 36¼ × 12⅝ × 16¾ | 43 lb | 343 lb |
| Marineland ML10300 “30 long” (dealer listing) | 36¼ × 129⁄16 × 16⅞ | 41 lb | 281 lb |
Checked 29 Sep 2026. Marineland lists 281 lb full, below the label 30 gallons × 8.34 lb plus the empty tank (291 lb). Aqueon's 343 lb is more than even the whole outside volume filled with water (320 lb); its chart notes that filled weights vary with substrate and decor. Neither includes the stand. The makers' "full" weights don't say how full; our set-up estimate further down uses the water left after 2 in of sand and a gap below the rim, plus the sand, so it can come out lower. Size your stand for the higher figure.
Same stand, three tanks
Aqueon builds three tanks on the same 36¼ × 12⅝ footprint. Only the height changes, so one stand, lid and 36 in light fit all three:
| Tank | L × W × H (in) | Outside volume |
|---|---|---|
| 30 gallon | 36¼ × 12⅝ × 16¾ | 33.2 gal |
| 38 gallon | 36¼ × 12⅝ × 19¾ | 39.1 gal |
| 45 gallon | 36¼ × 12⅝ × 23¾ | 47.1 gal |
Aqueon size chart. Marineland's 40 gallon high (36¼ × 12 9/16 × 20 13/16 in) sits on the same footprint.
Weights climb fast up the family: Aqueon lists 343, 427 and 515 lb full. Buy the stand for the biggest tank you might move to.
30 gallon vs 29 gallon
The names are one gallon apart but the tanks are not interchangeable:
| Aqueon | L × W × H (in) | Footprint | Water, bare bottom |
|---|---|---|---|
| 30 gallon | 36¼ × 12⅝ × 16¾ | 3.2 sq ft | 29.1 gal |
| 29 gallon | 30¼ × 12½ × 18¾ | 2.6 sq ft | 27.0 gal |
- The 30 is 6 in longer and 2 in shorter. It needs a 36 in stand, lid and light; the 29 uses 30 in ones.
- More length, easier reach. Active swimmers get 6 in more room, and at 16¾ in tall the bottom is easier to reach than in a 29.
- Similar water. Our bare-bottom estimates are within a couple of gallons (1/4 in glass, 1 in gap), so choose on shape and the space you have.
How much water a 30 gallon really holds
Multiply the outside dimensions of an Aqueon 30 and you get 33.2 gallons. You never get that much water, because of three things:
- Glass. With about 1/4 in glass (an estimate; check your tank), the inside is roughly 35¾ × 12⅛ in.
- The gap at the top. Most people keep the water about an inch below the rim.
- Substrate. Two inches of sand takes up about 14 litres of space.
That leaves about 29.1 gallons with a bare bottom and 25.3 gallons with 2 in of sand. Use the real figure, not the label, when you dose medication or water conditioner.
Weight and stand
A set-up Aqueon 30 comes to about 304 lb: 43 lb of glass, about 211 lb of water and about 50 lb of sand, before rock and the stand itself. That sits on 3.2 square feet.
- A set-up 30 weighs about 304 lb. Use a stand made for 36 × 12 tanks.
- If you might move up to a 38 or 45 later, buy a stand rated for the bigger tank; the footprint is the same.
General guidance, not structural advice.
Will a 30 gallon fit? Stand, doorway and floor
What stand does a 30 gallon need?
One with a top at least 36¼ × 12⅝ in, the Aqueon footprint, rated for at least 343 lb. That is the higher of the makers' full weights; our own set-up estimate is 304 lb. The whole bottom frame must sit on the stand, with nothing hanging over the edge.
Will a 30 gallon fit through a door?
Usually, yes. Carried end-first, the doorway only has to clear the tank's narrowest side, 12⅝ in (32 cm), plus room for your hands. The 36¼ in length only matters on tight turns in halls and stairs. Empty, it weighs about 43 lb (Aqueon).
Can my floor hold a 30 gallon?
Set up, it puts about 304 lb on 3.2 sq ft, or about 96 lb per square foot, before the stand. US homes are designed for 40 lb per square foot spread over a whole living-room floor (IRC Table R301.5), so a tank concentrates its weight. Under about 400 lb, any sound floor normally takes it. That weight band is our rule of thumb, not a code limit. Check your exact setup.
Equipment for a 30 gallon
| Item | Starting point | How we got it |
|---|---|---|
| Heater | 76–127 W | 3–5 W per gallon of real water; use the higher end in a cold room. |
| Filter | 101–152 gph | Turning over the water 4–6 times an hour |
| Sand, 2 in deep | ≈ 50 lb | Inside floor area × depth at about 1.6 kg per litre (estimate) |
| Light | 36 in | Match the tank length |
| Lid | 36 × 12 in | Check the maker's fit list |
Rules of thumb, not guarantees. Fish choice, room temperature and filter type all change the right answer.
What a 30 gallon is good for
Three feet of length suits small schooling fish and a community tank with some open swimming room. Check any mix in the stocking calculator.
How the numbers are worked out
Worked examples
Aqueon 30, 1/4 in glass, 1 in gap, 2 in sand: inside 35.75 × 12.12 in, water height 16.75 − 0.25 − 1 − 2 = 13.5 in. 35.75 × 12.12 × 13.5 = 5,852 in³ ÷ 231 = 25.3 gal (95.9 L).
Marineland 30, 1/4 in glass, 1 in gap, 2 in sand: inside 35.75 × 12.06 in, water height 16.875 − 0.25 − 1 − 2 = 13.62 in. 35.75 × 12.06 × 13.62 = 5,876 in³ ÷ 231 = 25.4 gal (96.3 L).
Bare-bottom Aqueon 30, 1/4 in glass, 1 in gap, 0 in sand: inside 35.75 × 12.12 in, water height 16.75 − 0.25 − 1 − 0 = 15.5 in. 35.75 × 12.12 × 15.5 = 6,719 in³ ÷ 231 = 29.1 gal (110.1 L).
FAQ
What are the dimensions of a 30 gallon fish tank?
About 36 × 12 × 16 in. Aqueon lists 36¼ × 12⅝ × 16¾ in and Marineland's 30 long 36¼ × 12 9/16 × 16⅞ in.
Is a 30 gallon the same as a 30 long?
Yes, in practice. Marineland calls its 36 × 12 × 16 in tank a 30 long; Aqueon calls the same size a 30. A 30 breeder is a different, 18 in deep tank.
How much does a 30 gallon tank weigh full?
Aqueon lists 343 lb and Marineland 281 lb. Our estimate with 2 in of sand is about 304 lb.
Will a 29 gallon stand fit a 30 gallon tank?
No. A 29 is 30¼ in long and a 30 is 36¼ in, so the 30 overhangs a 29 stand by 6 in.
How many litres is a 30 gallon tank?
30 US gallons is 113.6 litres. Set up, expect about 96–110 litres of actual water.
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Sources
- Aqueon aquarium size and weight chart, aqueon.com (PDF): www.aqueon.com
- Marineland standard aquariums, Bluefish Aquarium (dealer): bluefishaquarium.com
- Marineland 30 Gallon Long ML10300, Bluefish Aquarium: bluefishaquarium.com
- Aquarium Weights & Sizes, SaltwaterAquarium.com: www.saltwateraquarium.com
- All accessed 29 Sep 2026. Calculations by TankRatio; “estimate” and “rule of thumb” figures are ours.
Other tank sizes
- 5 gallon16 × 8 × 10 in
- 10 gallon20 × 10 × 12 in
- 15 gallon24 × 12 × 12 in
- 20 gallon long30 × 12 × 12 in
- 20 gallon tall24 × 12 × 16 in
- 29 gallon30 × 12 × 18 in
- 40 gallon breeder36 × 18 × 16 in
- 50 gallon36 × 18 × 19 in
- 55 gallon48 × 13 × 21 in
- 75 gallon48 × 18 × 21 in
- 90 gallon48 × 18 × 24 in
- 125 gallon72 × 18 × 22 in