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15 Gallon Tank Dimensions
A standard 15 gallon tank is about 24 × 12 × 12 in (61 × 30 × 30 cm) on the outside, holds about 10–12 gallons (40–45 litres) of water once set up, and weighs about 140–150 lb (65–70 kg) filled. Exact sizes vary by brand: Aqueon lists 24¼ × 12½ × 12¾ in and Marineland 24 × 12 × 12 in. The water and weight figures assume 2 inches of sand and water 1 inch below the rim.
- How long is a 15 gallon tank? About 24 in (61 cm). Aqueon: 24¼ in; Marineland: 24 in.
- How tall is a 15 gallon tank? About 12 in (30 cm). Aqueon: 12¾ in; Marineland: 12 in.
- How wide (front to back) is a 15 gallon tank? About 12 in (30 cm). Aqueon: 12½ in; Marineland: 12 in.
- How much does a 15 gallon tank weigh? About 21 lb empty (Aqueon; Marineland 22 lb) and about 154 lb set up with water and 2 in of sand, on 2.1 sq ft of floor. Add your stand and rock.
- How much gravel or sand for a 15 gallon tank? About 33 lb of sand or 27 lb of gravel for a 2 in bed. Work out other depths and bags.
- Is a 15 gallon the same footprint as a 20? As a 20 tall, yes (24 × 12 in); a 20 long is 6 in longer.
15 gallon tank calculator
Drawn to scale from your numbers: sand at the bottom, water up to your fill line.
Equipment for a 15
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Setting up a 15?
- 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 15 gallon is the same size
The “15 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 (15) | 24¼ × 12½ × 12¾ | 21 lb | 170 lb |
| Marineland 15 gallon (dealer listing, rounded size) | 24 × 12 × 12 | 22 lb | 142 lb |
Checked 29 Sep 2026. Marineland lists 142 lb full, below the label 15 gallons × 8.34 lb plus the empty tank (147 lb). Aqueon's 170 lb is more than even the whole outside volume filled with water (161 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.
The 15 gallon next to its neighbours
The 15 sits on the same 24¼ × 12½ footprint as the 20 tall, but only 12¾ in tall:
| Tank | L × W × H (in) | Outside volume |
|---|---|---|
| 10 gallon | 20¼ × 10½ × 129⁄16 | 11.6 gal |
| 15 gallon | 24¼ × 12½ × 12¾ | 16.7 gal |
| 20 gallon tall (high) | 24¼ × 12½ × 16¾ | 22.0 gal |
Aqueon size chart.
A stand, lid and 24 in light bought for a 15 gallon fit a 20 tall too, but check the stand's weight rating: Aqueon lists 170 lb full for the 15 and 225 lb for the 20 tall.
15 gallon vs 10 gallon vs 20 tall
A 15 is the middle step between two far more common tanks, and the numbers show what you gain at each step (Aqueon sizes, 2 in of sand, our estimates):
| Aqueon | L × W × H (in) | Footprint | Real water |
|---|---|---|---|
| 10 gallon | 20¼ × 10½ × 12⁹⁄₁₆ | 1.5 sq ft | 8.2 gal |
| 15 gallon | 24¼ × 12½ × 12¾ | 2.1 sq ft | 12.0 gal |
| 20 gallon tall | 24¼ × 12½ × 16¾ | 2.1 sq ft | 17.0 gal |
- Against a 10: 4 in more length and 2 in more width give about 3.8 gallons more real water.
- Against a 20 tall: the footprint is identical, so the extra 5.0 gallons of the 20 tall come entirely from 4 in of height.
- Low and wide: at 12¾ in tall the bottom is easy to reach for planting and cleaning, and the surface is close enough that a short lid or a 24 in light covers it.
How much water a 15 gallon really holds
Multiply the outside dimensions of an Aqueon 15 and you get 16.7 gallons. You never get that much water, because of three things:
- Glass. With about 3/16 in glass (an estimate; check your tank), the inside is roughly 23⅞ × 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 9 litres of space.
That leaves about 14.5 gallons with a bare bottom and 12.0 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 15 comes to about 154 lb: 21 lb of glass, about 100 lb of water and about 33 lb of sand, before rock and the stand itself. That sits on 2.1 square feet.
- Set up, a 15 gallon weighs about 154 lb on a footprint of just 2.1 sq ft, about 73 lb per square foot. Most sturdy furniture handles that, but check the rating.
- Marineland's 142 lb full figure uses the rounded 24 × 12 × 12 in size. Aqueon's 170 lb is closer to a completely full tank with its thicker trim.
General guidance, not structural advice.
Will a 15 gallon fit? Stand, doorway and floor
What stand does a 15 gallon need?
One with a top at least 24¼ × 12½ in, the Aqueon footprint, rated for at least 170 lb. That is the higher of the makers' full weights; our own set-up estimate is 154 lb. The whole bottom frame must sit on the stand, with nothing hanging over the edge.
Will a 15 gallon fit through a door?
Usually, yes. Carried end-first, the doorway only has to clear the tank's narrowest side, 12½ in (32 cm), plus room for your hands. The 24¼ in length only matters on tight turns in halls and stairs. Empty, it weighs about 21 lb (Aqueon).
Can my floor hold a 15 gallon?
Set up, it puts about 154 lb on 2.1 sq ft, or about 73 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 15 gallon
| Item | Starting point | How we got it |
|---|---|---|
| Heater | 36–60 W | 3–5 W per gallon of real water; use the higher end in a cold room. |
| Filter | 48–72 gph | Turning over the water 4–6 times an hour |
| Sand, 2 in deep | ≈ 33 lb | Inside floor area × depth at about 1.6 kg per litre (estimate) |
| Light | 24 in | Match the tank length |
| Lid | 24 × 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 15 gallon is good for
Two feet of length suits a small group of nano fish or a pair of dwarf cichlids, and the shallow depth is good for carpeting plants. It is too short for active danios or most livebearer groups to swim freely. Check any mix in the stocking calculator.
How the numbers are worked out
Worked examples
Aqueon 15, 3/16 in glass, 1 in gap, 2 in sand: inside 23.88 × 12.12 in, water height 12.75 − 0.1875 − 1 − 2 = 9.562 in. 23.88 × 12.12 × 9.562 = 2,768 in³ ÷ 231 = 12.0 gal (45.4 L).
Marineland 15, 3/16 in glass, 1 in gap, 2 in sand: inside 23.62 × 11.62 in, water height 12 − 0.1875 − 1 − 2 = 8.812 in. 23.62 × 11.62 × 8.812 = 2,420 in³ ÷ 231 = 10.5 gal (39.7 L).
Bare-bottom Aqueon 15, 3/16 in glass, 1 in gap, 0 in sand: inside 23.88 × 12.12 in, water height 12.75 − 0.1875 − 1 − 0 = 11.56 in. 23.88 × 12.12 × 11.56 = 3,347 in³ ÷ 231 = 14.5 gal (54.9 L).
FAQ
What are the dimensions of a 15 gallon fish tank?
About 24 × 12 × 12 in. Aqueon lists 24¼ × 12½ × 12¾ in; Marineland's dealer listing gives the rounded 24 × 12 × 12 in.
How much does a 15 gallon tank weigh full?
Aqueon lists 170 lb and Marineland 142 lb. Our estimate with 2 in of sand is about 154 lb.
How many litres is a 15 gallon tank?
15 US gallons is 56.8 litres. Set up, expect about 40–55 litres of actual water.
Will a 20 gallon tall fit a 15 gallon stand?
The footprint matches (24 × 12 in), so it fits. Check the weight rating: the 20 tall is about 55 lb heavier full by Aqueon's figures.
What size lid fits a 15 gallon tank?
A 24 × 12 in lid and a 24 in light fit a standard 15 gallon, and the same ones fit a 20 gallon tall.
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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 15 Gallon, 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
- 20 gallon long30 × 12 × 12 in
- 20 gallon tall24 × 12 × 16 in
- 29 gallon30 × 12 × 18 in
- 30 gallon36 × 12 × 16 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