FishTankAquarium substrate calculator
How much gravel or sand do you need? Pick your tank or enter its length and width, choose how deep you want it, and this calculator works out the pounds, the liters and how many bags to buy.
Use the inside measurements of the tank, or the outside ones minus the glass. This calculator uses about 100 pounds per cubic foot, which is close for most gravel and sand. Plant soils are much lighter, so for soil, buy by liters, not pounds.
A substrate that fits
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How deep should aquarium gravel or sand be?
- 1 to 2 inches for most fish-only tanks. Easy to keep clean.
- 2 to 3 inches for planted tanks, so roots have room to spread. Many people slope it from about 1.5 inches at the front to 3 at the back, which looks deeper and keeps the front easy to vacuum.
- About 1 inch of sand is plenty for corydoras and loaches, which like to sift through it.
- Avoid deep sand beds over about 3 inches unless you stir them now and then, because pockets with no oxygen can build up.
How much substrate do I need? Quick chart
For a flat layer 2 inches deep, worked out the same way as the calculator above:
| Tank | Footprint | For 2 inches |
|---|---|---|
| 5.5 gallon | 16 × 8 in | about 15 lb |
| 10 gallon | 20 × 10 in | about 25 lb |
| 20 gallon high | 24 × 12 in | about 35 lb |
| 20 gallon long | 30 × 12 in | about 40 lb |
| 29 gallon | 30 × 12 in | about 40 lb |
| 40 gallon breeder | 36 × 18 in | about 75 lb |
| 55 gallon | 48 × 13 in | about 70 lb |
| 75 gallon | 48 × 18 in | about 100 lb |
| 125 gallon | 72 × 18 in | about 150 lb |
Gravel, sand or soil?
Gravel is the easiest for beginners, sand is best for bottom dwellers like corydoras, and plant soil grows the best plants but costs more. See the best aquarium gravel and sand for the full comparison.
Tips
- Rinse gravel and sand in a bucket until the water runs mostly clear. Don't rinse plant soil unless the bag says to.
- Pour water onto a plate when you fill the tank, so it doesn't dig holes. See how to set up a fish tank.
- Substrate adds real weight. A 55 gallon with 2 inches of gravel carries about 70 pounds of it. See the tank weight calculator.
Related: Tank weight calculator · Aquarium volume calculator · Best gravel and sand