Use these free calculators to plan your next aquarium build — tank volume, substrate, heaters, water changes, and more.
Tools
Free calculators and practical helpers for your next aquarium project.
Aquarium Volume Calculator
Estimate the volume of a rectangular tank using its internal dimensions.
Estimated water volume
14.96 US gal
56.63 liters
Estimate only. Substrate, decorations and equipment reduce actual water volume; allow for glass thickness and fill height.
Substrate Calculator
Estimate how much substrate you need from tank footprint and target depth.
Estimated substrate
—
Estimate only. Densities vary by brand and moisture; buy a little extra for slopes and hardscape.
Heater Wattage Estimator
Rule-of-thumb estimate based on tank volume and how many degrees you need to raise the water.
Suggested heater size
—
Estimate only (common 3–5 watts per US gallon guideline). Room insulation, lid use, and heater placement matter. Prefer a slightly larger heater or two smaller ones for large tanks.
Water Change Calculator
Convert a water-change percent into gallons or liters to remove and replace.
Water to change
—
Uses filled water volume. Substrate and hardscape reduce actual water, so measure your true volume if precision matters.
Filter Flow Calculator
Estimate the pump or filter flow you should shop for based on tank size, target turnover, and expected flow loss.
Recommended rated flow
—
Real flow drops once media, tubing, and head height are added. Turnover is a planning guide, not a guarantee of adequate filtration. Marine sump returns are not the same as display-tank circulation.
Tank Weight Calculator
Estimate the filled weight of your aquarium for stand and placement planning.
Estimated filled weight
—
Extra load can include the empty tank, substrate, hardscape, cabinet top, and equipment. Always add a safety margin when evaluating a stand or floor.
Glass Thickness Estimator
Educational estimate for rectangular DIY tanks using annealed float glass and a safety factor of about 3.8.
Estimated minimum thickness
—
NOT engineering advice. Glass tanks can fail catastrophically. This is a simplified plate-bending estimate for annealed glass (MOR ≈ 6000 psi, SF ≈ 3.8, β ≈ 0.75). Tempered glass, braced panels, silicone joints, edge support, scratches, and local codes change requirements. Have a qualified fabricator or engineer size critical tanks.
Aquarium Unit Converter
Convert volume, temperature, and carbonate hardness units used in aquarium keeping.
Converted value
—
1 US gal = 3.785411784 L. °C = (°F − 32) × 5/9. 1 dKH ≈ 17.86 ppm as CaCO₃.
Planning a build? Browse DIY plans