Aquarium Calculators
Eight free tools with US and metric units, worked examples and clear assumptions.
Track your parameters over time with the ReefFlow app
Aquarium Volume
Estimate tank volume in US gallons or liters from four supported shapes.
Dosing (Alk/Ca/Mg)
Estimate a supplement dose for alkalinity, calcium or magnesium.
Salt Mix
Estimate salt mix for preparing a batch of new saltwater.
Substrate / Sand
Amount of substrate needed for your aquarium.
Salinity Converter
Convert between SG, PPT, PSU and conductivity.
Heater Size
Estimate heater wattage from water volume and temperature rise.
Electricity Cost
Calculate monthly and yearly cost of your equipment.
Water Change
Calculate water to replace and simulate parameter dilution.
Start with your aquarium’s actual water volume
Use the volume calculator to estimate tank capacity, then account for the space taken by rock, substrate and equipment before using that number for dosing or a water change. Each tool explains its calculation and assumptions below the form.
Formula and units
US units: US gallons, inches, °F, pounds and ounces. Metric units: liters, centimeters, °C, kilograms and grams.
Worked example
Planning a 50 US gallon water volume? A 20% water change means preparing 10 US gallons of new water. Use the salt mix calculator for that new batch, then check its measured salinity before use.
Assumptions and limits
English tools start with US units and Portuguese tools with metric units. Supplement doses remain in mL, salinity uses its own measurement scales, and electricity uses the currency and tariff you select. These estimates support planning; measurements and product instructions still matter.
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