Aquarium Substrate Calculator
The aquarium substrate calculator estimates how much sand, gravel or aragonite you need for your tank. Enter your tank shape and dimensions, choose your desired bed depth, and pick your substrate to get the weight in pounds or kilograms. It works as a sand calculator, gravel calculator and aragonite calculator in one.
Substrate density varies by material, so the right choice matters: a deep aragonite sand bed weighs more than a shallow gravel layer of the same footprint. A common starting depth is about 1 to 2 inches for a shallow reef look, or 3 to 4 inches for a deep sand bed. Ordering slightly extra makes aquascaping and depth tweaks easier.
Formula: Pounds = (footprint in² × depth in ÷ 1728) × substrate density (lb/ft³)
Estimate your substrate
Enter your aquarium details to estimate how much substrate you need for your tank based on the footprint, desired bed depth, and the sand, gravel or aragonite you plan to use.
Rectangle
Cube
Hexagon
Octagon
Flat Back Hexagon
Cylinder
Half Cylinder
Corner Cylinder
Elliptical
Corner Pentagon
L-Shaped
Corner Prism
Start Slow: Recommended Dosage
The values generated by this calculator are best used as a starting point. It is a good idea to make adjustments gradually and confirm results with follow-up testing instead of changing too much at once.
Rapid swings in tank parameters can create unnecessary stress, so slower adjustments are usually the safer approach. Monitor the system closely as you work toward your target.
How This Calculator Works
This calculator estimates the amount of sand needed by taking the footprint of your tank, multiplying it by your chosen sand bed depth, and then applying an approximate weight factor based on the sand type selected.
Tips for Best Results
- Double check your tank footprint before ordering sand.
- Account for rockwork and internal structures if you want a tighter estimate.
- Use the result as a planning guide rather than an exact final number.
- Ordering a little extra can help with aquascaping and depth adjustments.
Frequently Asked Questions
How much substrate do I need for my aquarium?
Multiply your tank footprint in square inches by your desired depth in inches, divide by 1,728 to get cubic feet, then multiply by the substrate density (roughly 85 to 105 lb per cubic foot depending on material). This calculator does the math for a dozen tank shapes and common sand, gravel and aragonite types.
How deep should my sand bed be?
For most reef tanks, a 1 to 2 inch shallow bed is easy to maintain and looks clean. A deep sand bed of 4 inches or more can aid denitrification but needs care. For freshwater planted tanks, 2 to 3 inches gives roots room to anchor.
Is sand or gravel better for an aquarium?
It depends on your livestock. Fine sand suits reef tanks, sand-sifting gobies and many bottom dwellers, while gravel is popular in freshwater and planted tanks for stability and root support. This calculator estimates weight for both, plus aragonite for buffering in marine systems.
