Skip to content
Fish Tank Volume Calculator

Aquarium Substrate Calculator

Volume

9 L

Weight

13.5 kg

29.8 lb

Approx. bags

2

at 10 kg each

Recommended depth: 2.5 to 5 cm for fish-only tanks, 5 to 7.5 cm for planted tanks.

Work out how much gravel, sand or aqua soil your aquarium needs. Enter the tank length, width and substrate depth and get the volume in litres and the weight in kilograms and pounds.

How to calculate aquarium substrate

Substrate volume is tank length times width times depth. Multiply the three in centimetres and divide by 1,000 for litres, then multiply by the substrate density to get the weight. Gravel is about 1.5 kg per litre, sand about 1.6 kg per litre and aqua soil about 0.9 kg per litre. Aim for 2.5 to 5 cm of depth in fish-only tanks and 5 to 7.5 cm in planted tanks.

Related calculators

Tank Weight Surface Area Stocking Glass Thickness In Gallons In Litres

Frequently asked questions

How much substrate do I need for my aquarium?
Multiply tank length by width by depth in centimetres, divide by 1,000 for litres, then multiply by the substrate density. The calculator shows litres, kilograms and pounds.
How deep should aquarium substrate be?
Allow 2.5 to 5 cm for fish-only tanks, and 5 to 7.5 cm for planted tanks so roots have room to spread.
How much does aquarium gravel weigh?
Gravel weighs about 1.5 kg per litre, so a 9 litre layer is roughly 13.5 kg.
Is sand or gravel heavier?
Sand packs denser, at about 1.6 kg per litre versus about 1.5 kg per litre for gravel.
How many bags of substrate do I need?
Divide the total weight by your bag size. The calculator estimates the number of 10 kg bags for you.
Does substrate reduce water volume?
Yes. Substrate displaces water, so subtract the substrate volume from the tank volume to estimate the real water capacity.

Related guides

Learn the core ideas behind fish tank volume before or after using the calculator.