Setup calculator
Aquarium Substrate Calculator
Estimate the substrate volume needed for a target bed depth, then convert that volume into rounded-up bag count.
How this calculator works
The calculator multiplies tank length by width by target substrate depth. Cubic centimeters convert to liters by dividing by 1000; cubic inches convert to liters by dividing by about 61.02.
Bag count is the substrate volume divided by the stated bag yield, rounded up so the estimate is usable for shopping.
Why it matters
Substrate depth affects plant rooting, burrowing behavior, water volume, and total tank weight. Estimating volume before buying reduces mismatched bags and makes the setup plan more predictable.
Worked example
A 36 by 18 inch footprint at 2 inches deep is 1296 cubic inches, or about 21.2 L. With 9 L bags, the rounded-up shopping estimate is 3 bags.
FAQ
Should I buy exactly the calculated bag count?
Buy at least the rounded-up bag count and add margin if you want slopes, terraces, or a deeper planted section.
Does substrate density matter?
Density matters for weight, but this calculator estimates volume because bag yield is usually sold by volume or coverage.
What depth should I use?
Use the finished bed depth you want after leveling. Planted tanks often need more depth than decorative bare-root layouts.
Does this include displacement by rocks?
No. It estimates the substrate bed under the full footprint unless you reduce the footprint for large hardscape areas.