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75 Gallon Tank Dimensions
A standard 75 gallon aquarium measures about 48 × 18 × 21 in (122 × 46 × 53 cm) on the outside. Exact sizes vary by brand: Aqueon lists 48½ × 18½ × 21⅛ in and Marineland 48⅜ × 18⅜ × 2015⁄16 in. Once it's set up with 2 inches of sand, it holds roughly 64–65 gallons of water and weighs about 720–740 lb in total.
75 gallon tank calculator
Drawn to scale from your numbers: sand at the bottom, water up to your fill line.
Setting up a 75?
- Plan your fish: the stocking calculator checks numbers and tank mates
- Size your heater for your room temperature
- Work out substrate in bags, not just pounds
Not every 75 is the same size
The "75 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 spec sheet | 48½ × 18½ × 21⅛ | 98 lb | 785 lb |
| Marineland ML10750 (retailer listing) | 48⅜ × 18⅜ × 2015⁄16 | 89 lb | 715 lb |
| Petco product page (Aqueon) | 49 × 19½ × 21¼ | – | – |
| SaltwaterAquarium.com size table | 48 × 18 × 21 | 140 lb | – |
Checked 24 Sep 2026. Full weights are the makers' own figures. Marineland's is simply the label gallons × 8.34 lb plus the empty tank; Aqueon's is closer to the full outside volume filled with water. Neither includes sand, rock or the stand, which is why the brands disagree. Some search answers quote about 850 lb full; that's only reached once you add rock.
Same stand, three tanks
Aqueon's 60 gallon breeder, 75 and 90 share one 48½ × 18½ footprint. Only the height changes. A stand built for any of them fits the others, as long as it's rated for the heaviest one you'll put on it.
| Tank (Aqueon) | L × W × H (in) | Outside volume |
|---|---|---|
| 55 gallon | 48¼ × 12¾ × 21 | 55.9 gal |
| 60 gallon breeder | 48½ × 18½ × 16 | 62.1 gal |
| 75 gallon | 48½ × 18½ × 21⅛ | 82.1 gal |
| 90 gallon | 48½ × 18½ × 25⅛ | 97.6 gal |
| 125 gallon | 72½ × 18½ × 23⅛ | 134.3 gal |
A 55 gallon is the same length and height but only 12¾ in deep, so a 55 gallon stand won't fit a 75. The 75 is 5¾ in deeper and overhangs the front or back.
How much water a 75 really holds
Multiply the outside dimensions of an Aqueon 75 and you get 82 gallons. You never get that much water, because of three things:
- Glass. With about ⅜ in glass (an estimate; check your tank), the inside is roughly 47¾ × 17¾ 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 28 litres of space.
That leaves about 72 gallons with a bare bottom and 65 gallons with 2 in of sand. Use the real figure, not the label, when you dose medication or water conditioner.
Weight, stand and floor
A set-up Aqueon 75 comes to about 740 lb: 98 lb of glass, about 540 lb of water and about 100 lb of sand, before rock and the stand itself. That load sits on about 6.2 square feet.
- Use a stand made for a 48 × 18 tank and rated above your total weight. Rock and a sump add up fast.
- Where you can, place the tank across the floor joists (not parallel to them) and close to a load-bearing wall.
- Under US residential codes, living-room floors are commonly designed for 40 lb per square foot spread across the room. A 75 puts far more than that on one spot. On older, upper or sagging floors, ask a builder or engineer first.
General guidance, not structural advice.
Equipment for a 75 gallon
| Item | Starting point for a 75 | How we got it |
|---|---|---|
| Heater | 200–325 W | 3–5 W per gallon of real water. Two smaller heaters at each end spread the heat and give a backup. |
| Filter | 260–390 gph | Turning over the water 4–6 times an hour. Planted and lightly stocked tanks sit at the low end. |
| Sand, 2 in deep | ≈ 100 lb | Inside floor area × depth at about 1.6 kg per litre (estimate; gravel varies) |
| Light | 48 in | Match the tank length |
| Lid | 2 × 24 in | Most 48 in lids come as two hinged halves. 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 75 is good for
The 18 in depth is the real upgrade over a 55: fish get room to turn, and you get room for layered aquascapes. Four feet of length suits active schooling fish and species that outgrow smaller tanks, such as angelfish, rainbowfish and larger tetra groups. Every fish list depends on the species mix, so check yours in the stocking calculator.
How the numbers are worked out
Worked examples
Aqueon 75, ⅜ in glass, 1 in gap, 2 in sand: inside 47.75 × 17.75 in, water height 21.125 − 0.375 − 1 − 2 = 17.75 in. 47.75 × 17.75 × 17.75 = 15,044 in³ ÷ 231 = 65.1 gal (246.5 L).
Marineland 75, same settings: 47.625 × 17.625 × 17.5625 = 14,742 in³ ÷ 231 = 63.8 gal (241.6 L).
Bare-bottom Aqueon 75, no sand: 47.75 × 17.75 × 19.75 = 16,739 in³ ÷ 231 = 72.5 gal (274.3 L).
FAQ
What are the dimensions of a 75 gallon tank in feet?
About 4 ft long, 1½ ft deep and 1¾ ft tall (48 × 18 × 21 in). Allow a few extra inches behind it for the filter and cables.
How much does a 75 gallon tank weigh full?
Aqueon lists 785 lb and Marineland 715 lb. Our estimate for an Aqueon with 2 in of sand is about 740 lb, before rock and the stand. Plan your stand and floor for 850 lb or more once you add rock.
Will a 55 gallon stand hold a 75 gallon tank?
No. Both are 48 in long, but a 55 is about 13 in deep and a 75 is about 18½ in. The 75 would overhang, and 55 stands usually aren't rated for the extra weight.
How many litres is a 75 gallon tank?
75 US gallons is 284 litres. Measured from the outside, an Aqueon 75 comes to 311 litres. Once it's set up, expect about 245–275 litres of actual water.
Is a 75 gallon the same footprint as a 90?
Yes, for Aqueon: both are 48½ × 18½ in. The 90 is 4 in taller. Aqueon's 60 gallon breeder also shares this footprint.
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Sources
- Aqueon aquarium size and weight chart, aqueon.com (PDF)
- Marineland 75 gallon ML10750 listing, Bluefish Aquarium
- Aqueon Standard Glass Aquarium 75 Gallon, Petco
- Aquarium Weights & Sizes, SaltwaterAquarium.com
- All accessed 24 Sep 2026. Calculations by TankRatio; "estimate" and "rule of thumb" figures are ours.