Aquarium Substrate Calculator
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Calculate how much aquarium substrate you need by tank size, depth, substrate type, and bag size.

Before you add substrate

- Decide whether the layout is flat, sloped, or planted before estimating depth.
- Check whether the substrate should be rinsed before use.
- Confirm the bag weight and density for the exact brand.
- Leave enough free space for hardscape, filters, and livestock needs.
- Check whether the bag is sold by kg, litres, or both before comparing products.
- Keep plant-root areas, decorative foregrounds, and deep back slopes separate when estimating.
- Account for displacement from large rocks, wood, caves, and filter hardware.
- Keep species-specific substrate requirements separate from the volume estimate.

When this estimate may be wrong

- Sloped aquascapes and deep planted areas can use more substrate than a flat average depth.
- Rocks, wood, and decor displace substrate and water volume.
- Some livestock need specific substrate types or depths that a volume calculator cannot decide.
- Bag count changes when a product is sold by litres instead of kg.
- Wet, rinsed, or porous substrates can behave differently from dry planning-density estimates.
- Deep anaerobic pockets, sharp gravel, or unsuitable grain size can be livestock-specific concerns.

Before buying substrate

Check the needs of your livestock and plants, then confirm bag weights, labelled litres, substrate density, rinsing instructions, and setup notes from the brand you plan to use. For sloped aquascapes, compare the flat average estimate with a deeper back-section estimate.

Disclaimer

Substrate depth depends on livestock, plants, and tank design. Check species-specific requirements.