Inputs used
- Tank length (cm)
- Tank width (cm)
- Desired substrate depth (cm)
- Substrate density (kg/L)
- Bag size (kg)
aquarium substrate calculator
How the Aquarium Substrate Calculator works
Assumptions, formula, inputs, and practical limits for the Aquarium Substrate Calculator.
How this estimate works
The calculator turns tank footprint and desired depth into volume, converts that volume to weight using substrate density, then rounds bag count up.
- Volume in litres = length x width x depth in cm divided by 1000.
- Weight = volume x substrate density x a 10% setup allowance.
- Bag count is always rounded up to avoid running short during layout.
Outputs generated
- litres of substrate
- kg/lb required
- bag count
- depth guidance
Worked example
A 90 x 45 cm tank with 5 cm of substrate needs about 20.3 litres. At 1.4 kg/L with a small allowance, that is about 31.2 kg, so four 9 kg bags.
Limits of the estimate
Substrate depth depends on livestock, plants, and tank design. Check species-specific requirements.
Check the needs of your livestock and plants, then confirm bag weights and substrate density from the brand you plan to use.