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Pounds of gravel, sand, or plant substrate for a fish tank at the depth you want.
With these inputs:
| Result | Value |
|---|---|
| Substrate needed | 40 lb |
| 20 lb bags | 2 bags |
| Volume | 3.1 gal (0.4 cu ft) |
| Footprint | 30" × 12" |
| Tank footprint | 30" × 12" (2.5 sq ft) |
| Depth | 2 in |
| Volume | 720 cu in |
| Weight | 40 lb |
| Bags | 2 bags |
Two inches of gravel is enough for most community tanks; planted tanks do better with 2.5 to 3 inches of aqua soil. Rinse gravel and sand before adding them.
The old rule of one pound of gravel per gallon only works for a thin layer in a standard tank. This aquarium gravel calculator uses the tank's actual footprint and your target depth to give the pounds of gravel, sand, or aqua soil to buy, and the number of bags.
A 29 gallon tank has a 30 by 12 inch footprint, so 2 inches of gravel is 720 cubic inches — about 40 pounds, or two 20 lb bags. For 3 inches, buy three bags.
It is a rough rule that gives about one inch of gravel in a standard tank. Tall tanks have a small footprint for their volume and need less; long and breeder tanks need more. Calculating from the footprint is more accurate.
About 2 inches for most freshwater tanks, 2.5 to 3 inches for planted tanks with rooted plants, and 1 inch or a bare bottom for tanks that need easy cleaning, such as breeding or quarantine tanks.
A 55 gallon tank is 48 by 13 inches. At 2 inches deep that is 1,248 cubic inches, or about 72 pounds of aquarium sand — four 20 lb bags.
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