30 gallon tank dimensions
Standard 30 gallon: 36 × 12 × 16 in · 91 × 30 × 41 cm
The everyday 30 gallon: a 3-foot tank with the 29's narrow 12-inch depth. Aqueon lists it at 36¼ × 12⅝ × 16¾ in outside the trim. The wider, shorter 36 × 18 × 12 version is the 30 gallon breeder.
Key stats
Dimensions (L × W × H)
36 × 12 × 16 in
91 × 30 × 41 cm
Volume (raw, outside)
30 US gal
113.3 L · 6912 in³
Water volume (with glass inset)
26 US gal
99.1 L
Manufacturer nominal
30 gal
Matches calculated
Footprint
3.00 ft²
432 in²
Empty weight (glass)
66 lb
30 kg · 0.375" glass, trim not included
Filled saltwater weight
346 lb
157 kg · 115 lb/ft² floor
Filled freshwater weight
315 lb
143 kg
Recommended glass (annealed)
10 mm
0.394 in · safety factor 3.8
Heater size (78°F target)
105 W
Redundant pair: 2× 75 W heaters
Substrate (2" sand bed)
43 lb
CaribSea Special Grade · 3 × 20-lb bags
Other 30 gallon tank sizes
"30 gallon" is sold in more than one shape. Same water, different footprint:
| Tank | L × W × H (in) | Footprint |
|---|---|---|
| Standard 30 gallon (this page) | 36 × 12 × 16 | 3.0 ft² |
| 30 gallon breeder | 36 × 18 × 12 | 4.5 ft² |
| Innovative Marine NUVO 30L | 24 × 18 × 16 | 3.0 ft² |
How many gallons is a 36 × 12 × 16 in tank?
A 36 × 12 × 16 in aquarium contains 30 US gallons by outside dimensions. The math:
36 × 12 × 16 = 6912 in³ 6912 ÷ 231 in³/gal = 29.92 US gal 29.92 × 3.785 = 113.3 L
In practice, actual water capacity is 26 gallons after subtracting 0.375" of glass thickness on each side. Manufacturers typically market this as a 30-gallon tank for round-number simplicity.
For a different shape (cylinder, hex, bow-front) or to enter custom dimensions, use the full aquarium volume calculator.
How much does a 30 gallon tank weigh?
- Saltwater reef (with ~26 lb live rock + 1" sand bed): 346 lb (157 kg)
- Freshwater (with a 1" gravel bed of ~25 lb, no rock): 315 lb (143 kg)
- Empty (glass alone): approximately 66 lb
- Floor load: 115 lb/ft² (saltwater filled)
Floor-load warning: at 115 lb/ft², this tank exceeds the 40 lb/ft² typical residential live-load rating. Place over a load-bearing wall or get a structural assessment before installing upstairs.
Full breakdown including equipment, sump, and custom rock weight: aquarium weight calculator.
Glass thickness for a 30 gallon tank
Using the Wisner hobby formula with a 3.8 safety factor, this tank requires:
- Annealed (regular float) glass: 10 mm minimum (0.394")
- Tempered glass: 5 mm minimum (tempered is ~4× stronger than annealed)
Most commercial tanks at this size ship one thickness step up for additional safety. See the glass thickness calculator for the full formula and Starphire (low-iron) options.
Heater size for a 30 gallon tank
In a warm room (~70 °F ambient) targeting 78 °F, this size tank needs about 105 W of heating. The conservative reefkeeping practice is to run two heaters at 75 W each: if one fails stuck-on, the other isn't powerful enough to cook the tank alone; if one fails stuck-off, the remaining one slows the temperature drop while you replace it.
For cold-room or cool-basement adjustments: heater wattage calculator.
How much sand or gravel for a 30 gallon tank?
- 2" sand bed: ~43 lb of CaribSea Special Grade aragonite (3 × 20-lb bags)
- 4" deep sand bed (DSB): ~85 lb
- 1" shallow / aesthetic: ~21 lb
Other substrate brands (Nature's Ocean, Tahitian Moon, Eco-Complete): substrate calculator.
Stocking a 30 gallon tank
Using the bio-load method from our stocking calculator (about 0.8 gallons per inch of slim adult fish, 1.2 for medium-bodied and 2 for heavy-bodied fish), a 30 gallon tank with about 26 gallons of water holds roughly 21 neon tetras, or 8 guppies, or 7 corydoras as a single-species tank. Mixed groups split that budget. Treat it as an upper bound: territory, swimming room and filtration can lower it, and each species' minimum group size and tank length still apply.
Choosing fish? See the best fish for a 29 gallon tank and how many fit, with stocking plans that work and the fish to avoid.
In total that is about 32 inches of small, slim-bodied fish (adult length), the figure the one-inch-per-gallon rule tries and fails to capture for anything bigger than a tetra.
Saltwater fish that fit a 30 gallon tank
- Banggai cardinalfish · 3" adult
- Clark's clownfish · 5" adult
- Royal gramma · 3" adult
- Six-line wrasse · 3" adult
- Firefish goby · 3" adult
- Ocellaris clownfish · 4" adult
- Yellow watchman goby · 4" adult
Check a specific mix for temperature, pH and schooling conflicts with the freshwater stocking calculator or the reef stocking calculator.
Equipment for this tank
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Salt, sand, heater and light picks sized for a 30-gallon tank.
High-alk, high-Ca reef salt. Spec sheet at 11.5–12.5 dKH.
Standard SPS-grade fixture. 24×24 in footprint at SPS PAR.
Best budget skimmer. Rated 55 gal heavy / 90 medium / 120 light bioload.
Most-recommended reef heater. Shatter-resistant.
Live aragonite, no rinse, 1–2 mm grain. Reef default.
The hobby standard magnetic algae scraper. Sizes for any tank.
Calibrate with 35 ppt fluid monthly. Replaces hydrometers.
The hobbyist standard for alkalinity testing.
FAQ
- What are the dimensions of a 30 gallon tank?
- A 30 gallon tank measures 36 × 12 × 16 inches (length × width × height), which is 91 × 30 × 41 cm, or 3 ft long, 1 ft front to back and 1.33 ft tall. Different brands vary by up to about half an inch because of trim and glass thickness.
- How big is a 30 gallon tank?
- It is 3 ft long, 1 ft front to back and 1.33 ft tall, so it needs a stand whose top is at least 36 × 12 inches. Its footprint is 3.0 square feet, and it stands 16 inches tall before you add the stand and lid.
- How many gallons is a 36 × 12 × 16 in tank?
- A 36 × 12 × 16 in aquarium holds approximately 30 US gallons by outside dimensions (113.3 L). After subtracting a standard 0.375" glass thickness on each interior wall, the actual water capacity is about 26 US gallons.
- How much does a 30 gallon tank weigh?
- Empty, the glass alone weighs about 66 lb (trim and lid add a little). Filled with fresh water and a 1" gravel bed it weighs about 315 lb (143 kg). As a saltwater reef with ~26 lb of rock and a 1" sand bed it comes to about 346 lb (157 kg), which puts 115 lb per square foot on the floor under the stand.
- What glass thickness do I need for a 30 gallon tank?
- Using the Wisner hobby formula with a 3.8 safety factor, a 36 × 12 × 16 in tank needs at least 10 mm annealed (regular float) glass. Tempered glass can be 5 mm and still meet the same safety margin. This is the calculated minimum — most commercial tanks at this size ship with one step up for safety. See the glass thickness calculator for the full math.
- What size heater for a 30 gallon tank?
- For a tank in a warm room (~70 °F ambient), this size needs roughly 105 W of heating. For redundancy, run two heaters at 75 W each — heaters fail, and a single point of failure on tropical fish or coral is expensive.
- How much sand or gravel for a 30 gallon tank?
- A 2-inch sand bed in this footprint (36" × 12") needs approximately 43 lb of CaribSea Special Grade aragonite, or about 3 20-lb bags. For a deep sand bed at 4 inches, double that.
- Is a 30 gallon tank good for a reef?
- It can work as a reef, but the 36 × 12 × 16 in footprint is more commonly used for freshwater. Front-to-back depth under 18 inches limits aquascape options for SPS or LPS. Most reefers in this size range pick a wider, shallower alternative.
Run your own numbers
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