Aquarium Substrate Calculator - Sand & Gravel
Calculate exactly how much sand, gravel, or aquarium substrate you need. Free substrate calculator tells you pounds needed for any tank size. Perfect for planted tanks and reef aquariums.
Aquarium Substrate Calculator - Sand & Gravel
Calculate how much substrate you need for your aquarium. Visualize different depths and substrate types.
Standard aquarium gravel, ideal for most setups
Good depth for planted tanks
Common sizes: 5, 10, 20, or 50 lbs
How much aquarium substrate do I need?
Tank Length × Width × Desired Depth ÷ 12 = Cubic feet needed
Quick Reference
The right amount of substrate is essential for plant growth, beneficial bacteria colonization, and aesthetic appeal. Our aquarium substrate calculator helps you determine exactly how much sand, gravel, or aqua soil you need for any tank size, from 10 gallon to 200+ gallon aquariums.
Measure Tank Base
Measure the length and width of your tank's bottom. Use inside measurements for accuracy.
Choose Substrate Type
Select sand, gravel, or aqua soil. Each has different densities affecting the amount needed.
Determine Desired Depth
Enter your target depth. Planted tanks need 2-3 inches front, 3-4 inches back. Fish-only tanks can use 1-2 inches.
Calculate Amount
Get results in pounds and kilograms. The calculator accounts for substrate density differences.
Why it matters: Unnatural appearance and poor plant growth
Do this instead: Slope substrate from 2-3" front to 3-4" back
Why it matters: Cloudy water for days or weeks
Do this instead: Rinse thoroughly until water runs clear (except some plant substrates)
Why it matters: Running short due to rinsing loss and settling
Do this instead: Purchase 10-15% extra substrate
Why it matters: Reduced swimming space and anaerobic pockets
Do this instead: Keep substrate proportional to tank height
Pro tip: Taking time to measure accurately and understand these common pitfalls will save you money on equipment, prevent fish losses, and create a healthier aquatic environment. When in doubt, double-check your measurements!
Recommended Products:
Available Services:
FishStores.org helps you find local aquarium shops with the products and expertise you need. Our directory includes over 5,000 fish stores across the United States.
Frequently Asked Questions
How much substrate do I need for my aquarium?
Calculate using tank length × width × desired depth ÷ 12 to get cubic feet, then multiply by substrate weight per cubic foot. Our calculator handles this automatically for sand, gravel, and aqua soil types.
What's the ideal substrate depth for planted tanks?
Planted tanks need 2-3 inches at the front sloping to 3-4 inches at the back. This provides adequate root space for plants while creating visual depth. Deeper substrate supports larger root systems.
How many pounds of sand do I need for a 20 gallon tank?
A standard 20-gallon long (30×12 inches) needs about 20-30 pounds of sand for a 1.5-2 inch depth. Use our calculator for exact amounts based on your desired depth and sand type.
How much substrate for a 10 gallon tank?
A 10-gallon tank (20×10 inches) needs approximately 10-15 pounds of substrate for a 1.5-2 inch depth. For planted tanks, use 15-20 pounds to achieve 2-3 inch depth.
How much substrate for 40 gallon breeder?
A 40-gallon breeder (36×18 inches) requires 40-60 pounds of substrate for standard 2-inch depth, or 60-80 pounds for a planted tank with 3-inch average depth.
Sand vs gravel for aquarium substrate?
Sand is better for bottom-dwelling fish and rooting plants but requires more maintenance. Gravel allows better water flow and is easier to vacuum but can trap more debris. Choose based on your fish and plant needs.
How many bags of substrate do I need?
Divide your total pounds needed by the bag weight. Most aquarium substrates come in 20-pound bags. For example, if you need 60 pounds, buy 3 bags. Always get one extra bag for future use.
Does substrate go bad or need replacing?
Quality substrate lasts years with proper maintenance. Replace if it becomes compacted, loses buffering capacity, or develops anaerobic pockets. Most aquarists do partial substrate changes every 2-3 years.
Setting Up Substrate?
Don't forget these important calculations:
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Precise measurements are the foundation of successful aquarium keeping. Whether you're calculating water volume for medication dosing, determining substrate amounts for a planted tank, or sizing equipment like heaters and filters, accuracy prevents costly mistakes and ensures the health of your aquatic pets. Our calculators take the guesswork out of aquarium math, helping both beginners and experienced aquarists make informed decisions.