Aquarium Guides
Short, practical guides written around our calculators. Just the numbers and why they matter.
Guides
Volume
How to Measure an Aquarium (and Get the Real Gallons)
Measure a fish tank the right way: inside vs outside dimensions, glass thickness, the real water height and odd shapes, with a worked example in inches and centimeters.
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Setup
How Much Does a Fish Tank Weigh? Filled Weight by Size
Filled aquarium weight for every standard size from 10 to 120 gallons: water, glass and gravel, the load on your stand and floor, and how to estimate any tank.
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Substrate
How Much Substrate Do I Need? Gravel and Sand Depth Guide
How deep aquarium gravel and sand should be, how to work out pounds and bags from your tank footprint, and why the "1 lb per gallon" rule is often wrong.
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Heating
Aquarium Heater Wattage Chart by Tank Size and Room Temperature
Heater wattage for 10 to 120 gallon tanks at different room temperatures, why "5 watts per gallon" is only a starting point, and when to use two heaters.
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Calculator walkthroughs
Each calculator page explains its formula, assumptions and common questions.
Volume
Aquarium volume
The complete walkthrough of tank volume: formulas, liters ↔ gallons conversion tables, gross vs actual water volume and a full FAQ.
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Heating
Aquarium heater sizing
Why "5 watts per gallon" is only a rule of thumb. Size a heater from real physics, decide one heater or two, and see goldfish and nano-tank advice.
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Heating
Heater size comparison
Compare wattages side by side (heat-up time, thermostat duty and cost) with interactive temperature curves, and learn why bigger never means pricier.
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Electricity
Aquarium electricity cost
Add up the heater, filter, lights, air pump and more: per-device and total kWh and cost per day, month and year at your tariff.
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Substrate
Aquarium substrate
Pounds, liters and bags of gravel, sand or aquasoil for a flat or sloped bed, with typical densities and recommended depths.
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Sizes
Aquarium sizes chart
Every standard tank from 10 to 120 gallons: dimensions, real water volume, filled weight and heater size, with a page per size.
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Missing a calculator?
Every tool here shows its formula and the assumptions behind it, so you can check the numbers by hand. Tell us what you are trying to work out and we will consider it for the next tool.