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50 Gallon Tank Dimensions
A standard 50 gallon tank is about 36 × 18 × 19 in (91 × 46 × 48 cm) on the outside, holds about 40–44 gallons (150–166 litres) of water once set up, and weighs about 470–510 lb (215–230 kg) filled. Exact sizes vary by brand: Aqueon lists 36⅜ × 18⅜ × 19 in and Seapora 36 × 18 × 18 in. The water and weight figures assume 2 inches of sand and water 1 inch below the rim.
- How long is a 50 gallon tank? About 36 in (91 cm). Aqueon: 36⅜ in; Seapora: 36 in.
- How tall is a 50 gallon tank? About 19 in (48 cm). Aqueon: 19 in; Seapora: 18 in.
- How wide (front to back) is a 50 gallon tank? About 18 in (46 cm). Aqueon: 18⅜ in; Seapora: 18 in.
- How much does a 50 gallon tank weigh? About 68 lb empty (Aqueon; Seapora publishes no weight) and about 507 lb set up with water and 2 in of sand, on 4.6 sq ft of floor. Add your stand and rock.
- How much gravel or sand for a 50 gallon tank? About 74 lb of sand or 59 lb of gravel for a 2 in bed. Work out other depths and bags.
- Is a 50 gallon the same footprint as a 40 breeder? Yes, both are 36 × 18 in, so a 40 breeder stand and hood fit a 50. The 50 is about 2 in taller.
- Does Marineland make a 50 gallon? We found none. Its 36 × 18 in tanks at dealers are the 40 breeder, 53 and 65 gallon.
50 gallon tank calculator
Drawn to scale from your numbers: sand at the bottom, water up to your fill line.
Equipment for a 50
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Setting up a 50?
- 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 50 gallon is the same size
The “50 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 (50, earlier edition) | 36⅜ × 18⅜ × 19 | 68 lb | 600 lb |
| Seapora 50 gallon (dealer listing, rounded size) | 36 × 18 × 18 | not listed | not listed |
Checked 29 Sep 2026. Seapora's dealer listing gives no weight, so its preset borrows Aqueon's 68 lb empty weight. Aqueon's 600 lb is more than even the whole outside volume filled with water (526 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 50 gallon next to its neighbours
The 50 shares a 36 × 18 footprint with the 40 breeder and the 65:
| Tank | L × W × H (in) | Outside volume |
|---|---|---|
| 40 gallon breeder | 363⁄16 × 18¼ × 1615⁄16 | 48.4 gal |
| 50 gallon | 36⅜ × 18⅜ × 19 | 55.0 gal |
| 65 gallon | 36⅜ × 18⅜ × 25 | 72.3 gal |
Aqueon size chart.
A 36 × 18 in stand and hood fit all three. Check the stand's rating for the tallest tank you might move to: Aqueon lists 458 lb full for the 40 breeder, 600 lb for the 50 and 775 lb for the 65.
50 gallon vs 40 breeder vs 55
People weigh the 50 against two nearby tanks. The numbers (Aqueon sizes, 2 in of sand, our estimates):
| Aqueon | L × W × H (in) | Footprint | Real water |
|---|---|---|---|
| 40 breeder | 36³⁄₁₆ × 18¼ × 16¹⁵⁄₁₆ | 4.6 sq ft | 37.5 gal |
| 50 gallon | 36⅜ × 18⅜ × 19 | 4.6 sq ft | 43.7 gal |
| 55 gallon | 48¼ × 12¾ × 21 | 4.3 sq ft | 44.2 gal |
- Against a 40 breeder: the same footprint, so the 50's extra 6.2 gallons of real water come from height alone.
- Against a 55: the 55 is 12 in longer but 5½ in narrower. The 50 gives a deeper front-to-back view for aquascaping, and the real water is about the same (43.7 gal against the 55's 44.2).
- Two different 50s: Aqueon's is 19 in tall, Seapora's listing is 18 in. That one inch is about 4.1 gallons of real water (Seapora 39.7 gal against Aqueon 43.7 gal, same glass and sand), so check the tank in front of you before trusting a 50 gallon number.
How much water a 50 gallon really holds
Multiply the outside dimensions of an Aqueon 50 and you get 55.0 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 35⅞ × 17⅞ 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 21 litres of space.
That leaves about 49.3 gallons with a bare bottom and 43.7 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 50 comes to about 507 lb: 68 lb of glass, about 365 lb of water and about 74 lb of sand, before rock and the stand itself. That sits on 4.6 square feet.
- Set up, a 50 gallon weighs about 507 lb on 4.6 sq ft, about 109 lb per square foot. That is heavy enough to plan a stand and floor position for.
- Aqueon's 600 lb full is above the whole outside box filled with water, so treat it as the rating to buy a stand for. Seapora lists no weight, so use Aqueon's figure as a guide.
General guidance, not structural advice.
Will a 50 gallon fit? Stand, doorway and floor
What stand does a 50 gallon need?
One with a top at least 36⅜ × 18⅜ in, the Aqueon footprint, rated for at least 600 lb. That is the higher of the makers' full weights; our own set-up estimate is 507 lb. The whole bottom frame must sit on the stand, with nothing hanging over the edge.
Will a 50 gallon fit through a door?
Usually, yes. Carried end-first, the doorway only has to clear the tank's narrowest side, 18⅜ in (47 cm), plus room for your hands. The 36⅜ in length only matters on tight turns in halls and stairs. Empty, it weighs about 68 lb (Aqueon).
Can my floor hold a 50 gallon?
Set up, it puts about 507 lb on 4.6 sq ft, or about 109 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. Between about 400 and 1,000 lb, stand it across the floor joists rather than along one, close to a load-bearing wall, on a level floor. That weight band is our rule of thumb, not a code limit. Check your exact setup.
Equipment for a 50 gallon
| Item | Starting point | How we got it |
|---|---|---|
| Heater | 131–219 W | 3–5 W per gallon of real water; use the higher end in a cold room. |
| Filter | 175–262 gph | Turning over the water 4–6 times an hour |
| Sand, 2 in deep | ≈ 74 lb | Inside floor area × depth at about 1.6 kg per litre (estimate) |
| Light | 36 in | Match the tank length |
| Lid | 36 × 18 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 50 gallon is good for
Three feet of length and 18 in of depth suit a community of mid-size fish, a pair of larger cichlids or a planted layout with room for hardscape. Check any mix in the stocking calculator.
How the numbers are worked out
Worked examples
Aqueon 50, 1/4 in glass, 1 in gap, 2 in sand: inside 35.88 × 17.88 in, water height 19 − 0.25 − 1 − 2 = 15.75 in. 35.88 × 17.88 × 15.75 = 10,100 in³ ÷ 231 = 43.7 gal (165.5 L).
Seapora 50, 1/4 in glass, 1 in gap, 2 in sand: inside 35.5 × 17.5 in, water height 18 − 0.25 − 1 − 2 = 14.75 in. 35.5 × 17.5 × 14.75 = 9,163 in³ ÷ 231 = 39.7 gal (150.2 L).
Bare-bottom Aqueon 50, 1/4 in glass, 1 in gap, 0 in sand: inside 35.88 × 17.88 in, water height 19 − 0.25 − 1 − 0 = 17.75 in. 35.88 × 17.88 × 17.75 = 11,382 in³ ÷ 231 = 49.3 gal (186.5 L).
FAQ
What are the dimensions of a 50 gallon fish tank?
About 36 × 18 × 19 in. Aqueon lists 36⅜ × 18⅜ × 19 in; Seapora's dealer listing gives 36 × 18 × 18 in.
How much does a 50 gallon tank weigh full?
Aqueon lists 600 lb. Seapora gives no weight. Our estimate with 2 in of sand is about 507 lb.
How many litres is a 50 gallon tank?
50 US gallons is 189 litres. Set up, expect about 150–187 litres of actual water.
Will a 40 breeder stand fit a 50 gallon?
The footprint matches (36 × 18 in), so it fits. Check the weight rating: Aqueon lists 458 lb full for the 40 breeder and 600 lb for the 50.
What size lid fits a 50 gallon tank?
A 36 × 18 in lid and a 36 in light fit. The same fit a 40 breeder and a 65.
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Sources
- Aqueon Critical dimensions chart, earlier edition that lists the 50 (PDF copy): swisstropicals.com
- Aqueon aquariums and stands incl. the 50 (36.4 × 18.4 × 19 in), Milwaukee Aquatics: www.milwaukeeaquatics.com
- Marineland standard aquariums (36 × 18 sizes), Bluefish Aquarium (dealer): bluefishaquarium.com
- Seapora 50 Gallon Aquarium 36x18x18, 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
- 30 gallon36 × 12 × 16 in
- 40 gallon breeder36 × 18 × 16 in
- 55 gallon48 × 13 × 21 in
- 75 gallon48 × 18 × 21 in
- 90 gallon48 × 18 × 24 in
- 125 gallon72 × 18 × 22 in