Substrate & Soil Depth Calculator.

Multiply the tank length by its width and your desired substrate depth to calculate the substrate volume. This calculator converts that volume to liters and estimates the weight based on the selected material. Substrate quantity depends mainly on the tank footprint and target depth, not simply the aquarium's gallon rating.

For a standard 20-gallon-long tank of approximately 30 × 12 inches with a 2-inch substrate bed, the calculated volume is about 11.8 liters. Using this calculator's planning densities, that is approximately 18.9 kg (41.7 lb) of gravel, 20.8 kg (45.9 lb) of sand, or 10.4 kg (23.0 lb) of aqua soil. These are planning estimates because actual products vary. A 20-gallon-high tank has a different footprint and may require a different amount.

For an approximate 48 × 13 inch footprint with a 2-inch substrate bed, the calculated volume is about 20.5 liters. Using this calculator's planning densities, that is approximately 32.8 kg (72.3 lb) of gravel, 36.0 kg (79.4 lb) of sand, or 18.0 kg (39.7 lb) of aqua soil. These are examples based on the calculator's planning densities, not universal product weights. Measuring your actual tank footprint gives a better estimate than relying on the '55 gallon' label.

Pounds-per-gallon is only a rough shortcut because substrate quantity is determined by floor area and bed depth rather than water capacity. A tall narrow aquarium and a long shallow aquarium can have the same gallon rating but require different amounts of substrate. For better accuracy, use the actual tank length, width, target depth, and substrate type.

This calculator reports estimated 9-liter bags based on substrate volume and 5-pound bags based on estimated substrate weight. Both values are rounded up to whole bags. Buying some extra can be useful if you plan to slope or reshape the bed, or want material available for future replacement.

Multiply tank length × width × desired substrate depth to get the substrate volume. Convert that volume to liters, then multiply by the estimated bulk density of the selected material to calculate its approximate weight. Gravel, sand, and aqua soil have different densities, so the same tank footprint can produce different weight estimates. The result is a planning estimate rather than an exact measurement of a specific product.

Around 1–2 inches is a common starting range for many fish-only aquariums, while roughly 2–3 inches is common for many planted tanks. These are general guidelines rather than universal requirements. Fish species, plants, substrate type, aquascape design, and whether the bed is sloped can all affect the preferred depth.

Roughly 2–3 inches is a common starting range for many planted aquariums, although some plants and aquascapes may benefit from deeper substrate or a sloped bed. Root depth, plant species, substrate type, and aquascape design all influence the amount needed, so there is no single depth that suits every planted tank.

Many aquarium gravels are coarse and inert, making them easy to work with and vacuum. Sand has finer particles and is useful for many bottom-dwelling fish and natural-looking layouts, although very fine beds can compact more easily. Aqua soil is a porous planted-tank substrate commonly used for rooted plants and aquascaping. This calculator uses different planning densities for each material because their typical bulk weights differ.

Substrate weight depends on the tank footprint, bed depth, material type, and the actual product's bulk density. This calculator uses approximate planning densities of 1.6 kg/L for gravel, 1.76 kg/L for sand, and 0.88 kg/L for aqua soil. Actual packaged weight can differ by brand, grain size, moisture, and how the substrate is packed.

Many gravel and sand products should be rinsed to remove dust and fine particles before they are added to an aquarium. However, product instructions vary, especially for specialty substrates, so follow the manufacturer's recommendations for the specific material you purchased.

Many active aqua-soil products should not be rinsed because handling them under running water can break down their granules or wash away fine material. However, products differ, so follow the manufacturer's instructions rather than assuming every aqua soil should or should not be rinsed.

Yes. Substrate occupies physical space that could otherwise contain water. The calculator's 'total volume' is the calculated volume of substrate itself, not the remaining water volume in the aquarium. Hardscape, decorations, equipment, and substrate can all reduce the actual amount of water compared with the tank's nominal capacity.

Yes. A sloped substrate bed generally requires more material than a flat bed at the same minimum front depth. This calculator assumes a uniform target depth, so if you want a significant front-to-back slope, allow for additional substrate rather than treating the flat-depth result as the exact amount required.