How much gravel for a 5.5 gallon tank?
16 × 8 × 10 in · freshwater planning
5.5 gallon · gravel & substrate
First decisions for this nano setup
In the 8-inch-wide base, a full two-inch bed consumes a noticeable part of the layout height. Start with the intended plant roots and choose depth from that need. For a thin decorative layer, use the one-inch row instead of automatically buying two inches of material.
Assumptions and limits
The old 1 lb/gal for roughly 1 inch and 1.5–2 lb/gal for 2 inches rules are loose shopping shortcuts. Here a 2-inch bed is 2.69 lb per nominal gallon. Footprint and bulk density explain the difference. Gravel and sand use 100 lb/ft³; aquasoil uses 60. Check bag coverage; grain size and moisture change density.
Bulk densities are stated planning assumptions; litre conversion: NIST conversion tables
5.5 gallon equipment and layout plan
A rectangular layout supports a straight front swimming lane and a rear equipment zone. The 16 × 8-inch base has an aspect ratio of 2:1. A lid or light must span roughly 16 inches; measure rim openings and bracket adjustment before ordering.
| Level bed | Sand bags, rounded up | Aquasoil bags, rounded up |
|---|---|---|
| 1 in | 7.41 lb / 1 × 20 lb | 2.1 L / 1 × 9 L |
| 2 in | 14.81 lb / 1 × 20 lb | 4.2 L / 1 × 9 L |
| 3 in | 22.22 lb / 2 × 20 lb | 6.29 L / 1 × 9 L |
A 1-inch front and 3-inch rear bed averages 2 inches, requiring 4.2 L. Across only 8 inches of width, that is a 25% grade. Check remaining water depth before making a steep nano layout.
Compared with the 5 gallon, this layout has the same 128 square inches of substrate coverage. Extra nominal capacity alone does not change this requirement.
The working
16 × 8 × 2 = 256 in³. Divide by 1,728 and multiply by 100 lb/ft³ = 14.81 lb. Round up to 1 bags of 20 lb.
| Depth | Gravel lb / 20 lb bags | Sand lb / 20 lb bags | Aquasoil lb / L |
|---|---|---|---|
| 1 in | 7.41 / 1 | 7.41 / 1 | 4.44 / 2.1 |
| 2 in | 14.81 / 1 | 14.81 / 1 | 8.89 / 4.2 |
| 3 in | 22.22 / 2 | 22.22 / 2 | 13.33 / 6.29 |
How to use this plan
- Measure the inside footprint; this plan uses 16 by 8 inches.
- Choose an average depth, allowing for slopes and hardscape.
- Calculate volume and mass as above; buy about 1 20 lb bags for a level 2-inch gravel bed.
Adjust measurements with the gravel & substrate calculator
Questions before you buy
What dimensions does this 5.5 gallon calculation use?
It uses a rounded 16 × 8 × 10 inch rectangle. Actual dimensions vary by brand and frame; measure your own tank.
What is the gravel & substrate estimate for a 5.5 gallon tank?
14.81 lb gravel for a 2-inch bed
Equipment to check
Compare aquarium substrate. Check dimensions, capacity and product instructions before buying.
As an Amazon Associate I earn from qualifying purchases.