Aquarium volume calculator
A tank measured inside at 60 × 30 × 36 cm holds 64.8 liters, also shown in US gallons. Enter length, width and water height in cm, mm, m, inches or feet to size the heater, filter and treatments. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Length
- 60 cm
- Width
- 30
- Height
- 36
- Volume m3
- 0.0648 cm
- Liters
- 64.8
- Gallons
- 17.1183489928
Knowing how many liters of water a rectangular aquarium actually holds is the first number every freshwater, marine, and planted-tank keeper needs: stocking density, heater wattage, filter turnover, dechlorinator dose, and salt mix all scale with volume. This aquarium volume calculator multiplies internal length by width by height, converts the cubic result into liters and US gallons with fixed SI factors, and rejects any dimension that is not a positive finite number so a zero-height sketch cannot become a fake fifty-gallon claim. Measure inside the glass, not the outer rim, because silicone seams and frame lips eat centimetres that never hold water. Optional unit defaults to centimetres, the way glass tanks are sold worldwide; inches, millimetres, metres, and feet are accepted so a US ten-gallon spec sheet and a sixty-centimetre rimless cube share one contract.
Measure internal length, width and water height in one unit
Height is the working water column, not the printed outer size on a box: leave a freeboard of a few centimetres so jumpers cannot leap and so a lid or light bar still fits, then send that lower height rather than the full pane. Glass thickness matters on rimless cubes and large display tanks; a labelled sixty by thirty by thirty-six centimetre tank can lose a centimetre on each inner axis, which is several liters you would otherwise over-dose.
Unit defaults to centimetres because that is how glass shops, rimless brands, and European livestock charts quote footprints; set unit to in when you are reading a North American ten-gallon, twenty-long, or fifty-five-gallon spec that lists inches, or to mm, m, or ft when a CAD drawing or stand plan already uses those scales. Mix systems offline first: do not send length in inches and height in centimetres in one body.
Substrate, rock, and hardscape displace water after the first fill; this calculator reports the empty rectangular capacity, which is the honest starting volume for a new tank before you subtract décor by eye or by displacement.
How length times width times height becomes liters and gallons
The engine treats the aquarium as a rectangular prism of water: cubic volume equals length times width times height in the chosen linear unit.
Those three lengths convert to metres with exact SI factors (one centimetre is 0.01 m, one inch is 0.0254 m, one foot is 0.3048 m, one millimetre is 0.001 m), then cubic metres convert to liters with one thousand liters per cubic metre and to US liquid gallons with the exact factor 3.785411784 liters per gallon, which is the same 231 cubic inches that US tank labels already assume.
A sixty by thirty by thirty-six centimetre tank is therefore 64.8 liters, a little over seventeen US gallons; a twenty by ten by twelve inch tank is the classic nominal ten-gallon footprint and comes out just over ten US gallons because the marketing size is rounded. Bow-front, hexagonal, and cylinder aquariums are outside this contract: they are not rectangular, and a fake width would lie about volume.
The calculator does not recommend fish counts, does not size a canister filter, and does not compute salt mix grams—it only returns volume so those workflows have a stable number to start from.
What you can do with it
Size a new rectangular fish tank before buying livestock
Hobbyists enter internal length, width and water height to learn liters and US gallons before applying a fish-per-gallon or centimetre-of-fish rule from their local shop.
Dose dechlorinator, medication and reef salt mix
Retail staff and reef keepers convert measured glass dimensions into liters so label rates for conditioner, copper, and synthetic seawater match the water actually in the tank.
Heater, filter and stand configurators
Marketplace and stand-builder tools batch catalog tank sizes into liters and gallons for wattage, turnover, and load estimates without retyping the prism formula.
FAQ
What happens if a dimension is zero or negative?
Zero or negative length, width or height cannot define a physical aquarium and are not charged.
Should I measure inside the glass or use the advertised outer size?
Measure internal length, width and the waterline height you will keep. Outer labels include glass thickness and freeboard that never hold water, so using them overstates volume for dosing.
Is the aquarium volume calculator free?
The browser tool runs free on your device.
Does this support bow-front, cylinder or corner aquariums?
This product uses the rectangular length × width × height prism. Bow-front, hexagonal, cylinder and corner tanks need a different geometry and are outside this contract.
How many liters does a 60 × 30 × 36 cm aquarium hold?
It holds 64.8 liters when those are the inside measurements and 36 cm is the water height. Gravel, rocks and décor take up part of that space, so the real water volume ends up a little lower.
Related tools
For developers — API access
Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.
API endpoint
Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, by email and from Telegram — and soon from our app too.
Call it from your stack
curl -X POST https://api.kit.forhosting.com/hobby/aquarium-volume \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"length":60,"width":30,"height":36}'const res = await fetch("https://api.kit.forhosting.com/hobby/aquarium-volume", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"length": 60,
"width": 30,
"height": 36
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/hobby/aquarium-volume",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"length": 60,
"width": 30,
"height": 36
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/hobby/aquarium-volume", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"length":60,"width":30,"height":36}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"length":60,"width":30,"height":36}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/hobby/aquarium-volume", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"length": 60,
"width": 30,
"height": 36
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "hobby.aquarium_volume",
"status": "queued",
"_links": {
"result": "/tasks/tsk_…/result"
}
}The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.
Pricing
Published price — no tokens, no invented credits. A failed task is never charged.
Limits
max_dim | 1000000 |
min_dim | 1e-12 |
Errors
| HTTP | Code | Meaning |
|---|---|---|
401 | unauthorized | Missing or invalid API key. |
402 | insufficient_balance | Your balance doesn't cover the task price. |
404 | unknown_type | That task type doesn't exist. |
429 | rate_limited | Too many requests. Use the webhook instead of polling. |
Technical notes
Measure internal length, width and water height in one unit
Walk a tape along the inside of the aquarium, not around the outer cabinet or plastic rim, and record three numbers that share one linear unit: length from left glass to right glass, width from front glass to back glass, and height from the bottom pane up to the waterline you will actually keep. Aliases such as len, breadth, and water_height map onto the same three fields so mobile forms and older quote tools can reuse keys. Missing any required dimension, a non-numeric string, zero, or a negative length, width, or height fails with invalid_input and is not billed.
How length times width times height becomes liters and gallons
The response echoes length, width, height, and unit, returns volume_m3 for engineering notes, liters for metric dosing and heater charts, gallons as US liquid gallons for North American livestock and filter labels, the formula string length * width * height, and method always equal to rectangular_aquarium so downstream code can branch without sniffing shapes. Identical inputs always produce identical JSON because the path is pure arithmetic with no network, random seed, or wall clock. Imperial (UK) gallons are not returned; if a UK label quotes imperial gallons, convert from liters with the published imperial factor outside this endpoint rather than treating US gallons as interchangeable.
API usage, pricing, stocking, dosing and practical limits
Call the free in-browser aquarium volume calculator for shopping-list checks, classroom volume labs, and shop-counter demos without opening a spreadsheet. Remember that substrate, wood, and rock mean the working water volume sits below the empty-glass capacity: for medication and salt, many keepers treat ten percent as a first displacement guess, or they fill to a mark, add décor, and refill from a measured container. Keep requests inside the published dimension limits, pin the rounded liters in tests, and you get reproducible aquarium volumes for homework of the fishkeeping kind, retail configurators, and edge workers without standing up a hydrostatics stack of your own. Send a JSON body with required length, width, and height, plus optional unit when dimensions are not in the default centimetres. Use the prepaid API when a livestock marketplace, aquarium-store quote tool, reef-salt mixer, or heater-wattage helper needs a stable contract under KIT balance at $0.002 per successful item; validation failures never consume balance after the engine rejects a non-positive dimension. Pair this endpoint with unit converters when a customer mixes inch-based US tank names with centimetre-based rimless glass, or with pond and pool volume tools when a property has both ornamental ponds and indoor display tanks—the search intent here is a rectangular fish tank, not a garden liner or a swimming pool. Authors shipping SDKs can map liters and gallons straight into product copy while showing volume_m3 and formula as explanatory detail for the technician reviewing a treatment ticket.
Technical questions
How do I calculate aquarium volume in liters and gallons from length, width and height?
Send JSON with length, width, height, and optional unit (cm default, or mm, m, in, ft). The response includes liters, gallons (US liquid), and volume_m3 from the rectangular product length × width × height.