Aquarium substrate calculator
Find how much gravel, sand or aqua soil your tank needs, in pounds and liters, from the footprint and your target depth.
How the amount is worked out
The calculator multiplies your tank length by its width and your chosen depth to get the volume of substrate in cubic inches, then converts that to weight using the density of the material. Gravel and sand weigh roughly 100 to 110 pounds per cubic foot, while lightweight aqua soil made for planted tanks is closer to 60 pounds per cubic foot, so the same depth of aqua soil weighs noticeably less.
Output is shown in pounds as the primary figure, with the volume in liters and a rough count of standard 20 pound bags alongside. Because bags are sold in fixed sizes and some material is lost to rinsing, plan to buy about ten percent more than the estimate. A little extra also lets you slope the substrate higher at the back, which looks natural and helps debris settle where it is easy to remove.
Choosing a depth
For a community tank with few or no plants, 1 to 2 inches of gravel or sand is plenty. It covers the base, gives beneficial bacteria a home and looks tidy without trapping too much waste. If you plan rooted plants, aim for 2 to 3 inches so roots can anchor and spread, and consider a nutrient rich aqua soil under a cap of sand or fine gravel.
Deeper is not always better. Very deep fine sand can form pockets with no oxygen, so keep sand beds shallower unless you keep burrowing species or maintain the bed carefully. Whatever you choose, rinse gravel and sand well before it goes in, and add it before you fill the tank so the water stays clear.
Frequently asked questions
How deep should aquarium substrate be?
About 1 to 2 inches of gravel or sand suits most community tanks. For rooted plants, aim for 2 to 3 inches so roots have room to anchor and spread.
How much does aquarium gravel weigh?
Aquarium gravel weighs roughly 100 to 110 pounds per cubic foot, sand is similar, and lightweight planted aqua soil is closer to 60 pounds per cubic foot. This tool uses those figures to estimate the weight for your tank.
Should I buy extra substrate?
Yes. Buy about ten percent more than the estimate to allow for uneven depth, rinsing losses and a slope from front to back. Leftover substrate is useful when you rescape.
Is sand or gravel better for a substrate?
Both work. Sand looks natural and suits bottom dwellers like corydoras, while gravel lets water flow through and anchors many plants well. Your choice affects depth and weight, which this calculator accounts for.