True water volume in gallons and liters, filled weight for your floor and stand, heater wattage, substrate amount, and water change volumes — from three measurements.
Curved fronts don't have one agreed formula industry-wide. This uses a parabolic-segment estimate, which checked out closely against a published tank spec but can differ from another calculator by a few percent on a pronounced curve.
Rated sizes describe the glass box filled to the rim. Real water volume loses the gap below the trim, displacement from substrate, rock, and wood, and often the space around internal equipment. 10–15% less than rated is normal, which matters when you dose medication or fertilizer by volume.
The calculator uses the footprint of your tank times your chosen depth, at a typical aquarium gravel density of about 1.6 kg per liter (100 lb per cubic foot). Lightweight planted-tank soils go further; sand packs slightly denser.
Loaded weight here is water weight plus roughly 30% for glass, stand, substrate, and hardscape. Tanks over about 100 gallons concentrate serious load — placing the stand across floor joists near a load-bearing wall distributes it far better than parallel to joists mid-span.
The old "one inch of fish per gallon" rule fails for anything except small slim-bodied fish. Stocking depends on filtration, surface area, temperament, and adult size — a single 10-inch oscar needs far more than a 10-gallon tank. Use volume as a starting constraint, then research each species' adult needs.