A free 4-in-1 aquarium calculator suite: fish tank volume in liters and gallons, safe stocking levels for your fish, glass & acrylic thickness estimates, and water treatment dosing (water changes, dechlorinator, aquarium salt, medication). Works for nano tanks, betta tanks and goldfish tanks alike.
Rectangular, bow front or cylinder tanks. Enter dimensions; get liters, US & UK gallons, water weight and estimated total setup weight.
Add fish by species and count. We check the classic inch-per-gallon rule and the surface-area rule (12 in² of surface per inch of fish) and give an honest verdict.
Rule-of-thumb glass thickness from published aquarium-building tables, based on water height. Includes acrylic estimate and bracing guidance.
Water changes, dechlorinator, aquarium salt, medication doses, heater size and substrate amount — all from your tank volume.
This fish tank calculator suite combines a fish tank volume calculator (with an aquarium gallons calculator and aquarium liter calculator, including a bow front aquarium calculator), a fish tank stocking calculator and aquarium bioload calculator for tropical fish stocking, an aquarium glass thickness calculator with an aquarium acrylic thickness calculator estimate and rimless aquarium guidance, plus an aquarium water change calculator, aquarium salt dosage and aquarium medication dosage tools, aquarium fertilizer dosing notes, an aquarium heater size calculator, an aquarium substrate calculator (how much gravel or sand you need), and an aquarium weight calculator — all in one page.
A rectangular tank is length × width × height ÷ 1000 = liters. A cylinder is π × r² × h ÷ 1000. A bow front tank adds a half-ellipse bulge to the rectangle: footprint = W×D + π×W×B÷4, times height. One US gallon = 3.785 liters; one UK (imperial) gallon = 4.546 liters. Freshwater weighs ~1 kg per liter, so a 64.8 L tank holds 64.8 kg of water — before glass, substrate and stand.
The inch-per-gallon rule says one inch of adult fish per US gallon of water (tropical), or one inch per two gallons for messy coldwater fish like goldfish. The surface-area rule says you need at least 12 square inches of water surface per inch of fish, because oxygen enters through the surface. We show both and take the stricter one.
Be honest with yourself about what these rules miss: a 10-inch common goldfish and ten 1-inch tetras are not equivalent, even though both are "10 inches". Aggression, territory, swimming space and filtration matter more than arithmetic. Tools like AqAdvisor model hundreds of species in depth — we deliberately don't try to copy that database; instead this suite gives you breadth (volume, glass, dosing) plus a transparent first-pass stocking check.
Glass thickness follows water height, not tank length: a tall narrow tank needs thicker glass than a long shallow one of the same volume. Our table (5 mm up to 30 cm … 19 mm above 90 cm) mirrors published DIY aquarium tables. Acrylic needs roughly 1.5–2× the glass thickness for the same span. Tanks taller than 60 cm benefit from top bracing; rimless designs should go one size thicker or stay shallow.
A 25% water change on 40 ppm nitrate leaves ~30 ppm (dilution math). Standard dechlorinator reference dose is 1 mL per 10 US gallons; aquarium salt for freshwater treatment is 1 tablespoon per 5 gallons; heaters are sized 3–5 W per gallon (use the upper end in cold rooms); substrate is about 1.6 kg per liter of bed volume for gravel. Fertilizer and CO₂ dosing are product-specific — dose per the manufacturer's label, this calculator doesn't guess them.
Yes. "Aquarium" and "fish tank" are used interchangeably in the hobby; every calculator on this page answers both phrasings. A nano aquarium is just a small one (typically under 10 gallons) — the same math applies, but stocking rules get stricter because small volumes are less stable.
Multiply length × width × height in inches and divide by 231 for US gallons, or enter centimeters above — the volume calculator converts to liters, US gallons and UK gallons automatically. A 60×30×36 cm tank holds 64.8 liters, about 17.1 US gallons.
Use the stocking tab above: add each species and count, and it checks the inch-per-gallon rule and the surface-area rule, then gives an understocked / fully-stocked / overstocked verdict. As a rough guide, one inch of adult tropical fish per US gallon is the classic starting point.
It is a rule of thumb, not science. It ignores temperament, territory, body shape and filtration — ten 1-inch tetras are not equivalent to one 10-inch goldfish. Use it as a first sanity check, then research each species. That honesty is why this tool also shows the surface-area rule and takes the stricter of the two.
Thickness follows water height: up to 30 cm → 5 mm, 30–40 cm → 6 mm, 40–50 cm → 8 mm, 50–60 cm → 10 mm, 60–75 cm → 12 mm, 75–90 cm → 15 mm. Above 90 cm, consult a professional builder. This is a rule-of-thumb from industry tables, not a structural engineering calculation.
Yes — acrylic needs roughly 1.5 to 2 times the glass thickness for the same span, which the glass tab estimates for you. Acrylic is lighter and clearer but scratches more easily.
10–25% weekly is the standard for most freshwater tanks. The dosing calculator shows the effect: a 25% change on 40 ppm nitrate leaves about 30 ppm. Heavily stocked or new tanks may need more frequent changes; test your water and adjust.
The standard reference dose is 1 mL per 10 US gallons (about 20 drops per mL). Always check your product label — brands and concentrations differ, and the label wins over any calculator.
For freshwater treatment, 1 tablespoon per 5 US gallons is the common reference dose. Do not use aquarium salt in reef tanks, and use caution with scaleless fish and live plants.
3–5 watts per US gallon is the rule of thumb — a 17-gallon tank needs roughly 50–85 W. Use the upper end if the room is cold. The dosing tab computes the range from your tank size.
Enter length, width and desired depth in the dosing tab — the aquarium substrate calculator uses about 1.6 kg per liter of gravel bed, so you know exactly how much gravel or sand to buy. A 60×30 cm tank with 5 cm of gravel needs roughly 14.4 kg. Aim for 5–8 cm depth for planted tanks.
Water is ~1 kg per liter, so water dominates: a 64.8 L tank holds 64.8 kg of water plus glass, substrate and stand. The volume tab estimates total setup weight including glass panels and substrate. Always place tanks on a stand rated for the filled weight.
A bow front is a rectangle plus a half-ellipse bulge: footprint = width × depth + π × width × bow ÷ 4, times height. Select "Bow front" in the volume calculator and enter the front bulge depth.
Bioload is the waste load your fish produce — driven by body mass, feeding and metabolism. Because mass scales roughly with the cube of length, a 4-inch fish produces far more waste than two 2-inch fish. That is why the inch-per-gallon rule is only a rough starting point.
No — and it does not try to. AqAdvisor models 917 species in depth; this suite wins on breadth (volume, glass, dosing in one place) and a modern mobile-friendly interface, with a transparent first-pass stocking check instead of a species database.
Not yet. As rough guidance: filters are typically rated for 1.5–2× your tank volume per hour turnover for freshwater; lighting depends on plants vs. fish-only setups. These need product-specific data we do not guess at.
Yes. This aquarium calculator runs 100% in your browser — your tank dimensions, fish list and doses never leave your device. There are no accounts, no uploads and no external requests.
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