PETS

◫

Aquarium volume and stocking calculator

Net litres, water changes and cautious fish screening

AQUARIUM PLANNING

How much water does the tank really hold?

Tank lengthcmTank depthcmWater heightcmSubstrate and décor%Water change%Conditioner per 10 LmlRated filter flowL/hFish typeAverage adult lengthcmPlanned fishn.

Calculation resultUpdates instantly

estimated net volume95.2 L

Result details

The space taken by substrate, rocks, wood and unfilled headroom is removed from gross volume.

Inside the result

Updates as you change the inputs

Gross volume112 L

Water to replace28.56 L

Dose for the change14.28 ml

Theoretical filter turnovers5.25 ×/h

Indicative cautious count9

Pressure versus guideline88.9%

The screen is not a safety guarantee. Always use adult size and check the needs of each species.

RESULT COMPARISON

Where does your result stand?

Reference range

Stocking versus cautious screenWithin the indicative cautious count

Your result: 8 fish · 5 cm adult size
Reference: Up to 9 fish in the screen
Difference: 1 spare

This is only an initial screen. Do not combine incompatible species or treat the count as permission to add fish. Surface area, behaviour, filtration, cycling and water remain decisive.

Stocking is only a cautious screen based on adult length. Species, behaviour, surface area, filtration, cycling and water quality remain decisive.

CalcuPop…

▣

Printable calculator sheet

Create an A4 reminder for this tool. Print it with the current values or blank, ready to complete by hand.

NameDate

A4 sheet preview

CALCUPOP · AQUARIUM VOLUME AND STOCKING CALCULATOR

Aquarium volume and stocking calculator

Completed summary using the values currently in the calculator

Name________________________________Date____________

01 · Calculation inputs

Complete the calculator or use the blank spaces below.

02 · Result and useful details

Result and useful details

________________
________________
________________

03 · Reminders, checks and notes

CalcuPophttps://calcupop.com

A CLEANER SITE, WITH YOUR HELP

Was it useful? Support CalcuPop.

Even a small voluntary contribution helps us keep these calculators free, clear and free from aggressive advertising.

Who’s behind CalcuPop

Support CalcuPopCard via Stripe or PayPalStripe or PayPal handles your payment. CalcuPop never sees or stores your card details.

DOES THE RESULT LOOK WRONG?

Help us improve this calculator.

HOW IT WORKS

A result to understand, not just read.

Calculate approximate net aquarium volume, water-change quantities and a cautious first stocking check. Internal dimensions and displacement matter more than the nominal model name.

OFFICIAL SOURCES

rspca.org.uk↗

FREQUENTLY ASKED QUESTIONS

How does aquarium volume and stocking calculator work?+

Internal water dimensions give gross litres; substrate, rocks and equipment are subtracted to estimate net water volume, which is then used for maintenance quantities.

What should I check before relying on the result?+

No litres-per-fish rule can guarantee welfare. Cycling, compatibility and water quality require species-specific research and regular testing.

RESULT GUIDE

How to use aquarium volume and stocking calculator

Calculate approximate net aquarium volume, water-change quantities and a cautious first stocking check. Internal dimensions and displacement matter more than the nominal model name.

01 · FORMULA

Calculation method

Vₙ = L × W × H ÷ 1.000 − D

Internal water dimensions give gross litres; substrate, rocks and equipment are subtracted to estimate net water volume, which is then used for maintenance quantities.

02 · WORKED EXAMPLE

Practical example

Measure internal length, width and actual water height, then estimate displacement from substrate and decoration.

The result shows gross and net litres, change-water volume and screening notes for the fish profile entered.

No litres-per-fish rule can guarantee welfare. Cycling, compatibility and water quality require species-specific research and regular testing.

03 · HOW TO READ IT

How to interpret the result

Use stocking guidance only after checking adult size, behaviour, water chemistry, filtration and social needs for each species.
Change one input at a time to understand which assumption has the greatest effect on the result.

04 · LIMITS

What the estimate does not include

No litres-per-fish rule can guarantee welfare. Cycling, compatibility and water quality require species-specific research and regular testing.
Use the result as a planning aid and confirm sensitive financial, health or animal-care decisions with the relevant document or qualified professional.