How much gravel do I need for a 55-gallon aquarium?

About 55–65 lbs for a standard 1–2 inch bed. The classic rule is 1 lb of gravel per gallon of tank capacity, which lands close to the volumetric calculation.

How much gravel for a 10-gallon tank?

About 10–15 lbs for a 1–2 inch bed. A 10-gallon tank has roughly a 20"×10" base; one 15 lb bag of aquarium gravel covers it well.

How much gravel for a 20-gallon tank?

About 20–25 lbs. The 20-gallon long has a 30"×12" base; the 20-gallon high has a 24"×12" base — both work out to similar gravel needs at the same depth.

What's the best gravel for a freshwater aquarium?

Aquarium-rated washed pea gravel for most community tanks — smooth, rounded, won't damage bottom-dwelling fish. Aquasoil (Fluorite, Eco-Complete) for planted tanks. Fine sand for cichlids and rays.

Can I use regular landscape gravel in a fish tank?

Not without testing. Landscape gravel may contain limestone (raises pH), residues from quarrying, or sharp edges. Aquarium-rated gravel is washed, pH-neutral, and smooth-edged. The cost difference for a small tank is negligible.

How deep should aquarium gravel be?

1–2 inches for community tanks. 2–3 inches for planted tanks. Less than 1 inch for sand-sifters. Never deeper than 3 inches — deeper beds develop anaerobic pockets that produce toxic hydrogen sulfide.

Do I need to rinse aquarium gravel?

Yes. Even bagged aquarium gravel has fine dust that will cloud your tank for days. Rinse a few pounds at a time in a 5-gallon bucket, swirl, drain, repeat until the water runs clear before adding to the tank.

Is painted aquarium gravel safe for fish?

Reputable aquarium-brand painted gravel is non-toxic and aquarium-safe — the coating is sealed. Avoid garden-center decorative gravel, which may have unsealed dyes that leach into the water. If you're unsure, stick to natural-colored washed pea gravel or aquarium-specific substrate.

What gravel is best for a planted aquarium?

For most stem and root plants, use aquarium-specific substrate like Fluval Stratum, Eco-Complete, or ADA Aqua Soil at 2–3 inches depth. Plain pea gravel works for low-light, low-demand plants (Anubias, Java fern, mosses) but won't supply nutrients to root-feeders. Don't mix substrate types in layers — anaerobic pockets form at the boundary.

Aquarium Gravel Calculator — Pounds

How this calculator works for aquariums

Aquarium substrate sits on the floor of the tank, so the calculation uses the tank footprint (length × width of the bottom glass), not the gallon capacity. Standard rectangular tanks have known footprints — a 55-gallon tank, for instance, has a 48"×13" base.

The "1 pound per gallon" rule is a fast cross-check: a 55-gallon tank takes roughly 50–60 lbs of gravel for a 2-inch bed. If your calculator result is wildly different from that ballpark, you've probably typed the wrong depth or units.

Always rinse aquarium gravel

Even bagged 'aquarium-grade' gravel comes coated in fine dust. Rinse it in batches in a 5-gallon bucket until the water runs clear before adding to the tank — otherwise you'll cloud the water for days.

Standard freshwater tanks are happiest at 1–2 inches of substrate. Planted tanks want 2–3 inches for root anchoring. Cichlid tanks with sand-sifting species use 0.5–1 inch of fine substrate. Avoid going deeper than 3 inches in any tank — anaerobic pockets form and produce hydrogen sulfide.

Recommended depth & material

Use	Depth	Material	Notes
Standard freshwater community tank	1" – 2"	Washed pea gravel or aquarium-grade gravel	Most common all-purpose setup.
Planted tank (low-tech)	2" – 3"	Aquarium gravel over root tabs, or aquasoil	Deeper bed for root anchoring.
Planted tank (high-tech, aquasoil)	2" – 3"	Commercial aquasoil (Fluorite, ADA, Eco-Complete)	Calculate by bag weight, not gravel density.
Cichlid / sand-sifter tank	0.5" – 1"	Pool filter sand or fine aragonite	Shallow bed; sand not gravel.
Bare-bottom (breeding/quarantine)	0"	None	Easier cleaning; no substrate at all.

How to measure for aquarium gravel

Measure the inside of the tank, not the outside dimensions — aquarium glass is typically 3/8 to 3/4 inch thick.

Measure the tank base inside the glass. Length and width of the bottom interior, in inches. For a 20-gallon long tank, that's roughly 30" × 12". Use millimeters and centimeters in metric mode if your tank is sized in liters.
Convert to feet for the calculator. Divide each dimension by 12. A 30"×12" base is 2.5 ft × 1 ft.
Pick your depth. 1" community, 2" standard, 2-3" planted. Don't exceed 3" — anaerobic dead zones form below that.
Use the 1 lb/gallon sanity check. After calculation, multiply your tank's gallon capacity by 1 lb. If the calculator's pound result is within 20% of that, your inputs are sane.
Buy bagged from an aquarium supplier. Bulk landscape gravel may have residues that affect water chemistry. Buy aquarium-rated gravel in bags — most tanks need 1-3 bags.
Round up generously. Aquarium gravel doesn't keep well in storage open to humidity. Buy 1 extra bag rather than 1 too few.

Worked example: 55-gallon tank, 2" of gravel

A standard 55-gallon tank has a base of approximately 48" × 13" (4 ft × 1.083 ft), giving 4.33 sq ft of footprint.

Volume: 4.33 × (2/12) = 0.722 cuft
Weight (pea gravel): 0.722 × (2,450/27) = ~65 lb
Sanity check: 1 lb/gallon rule says ~55 lb — close to our 65 lb (the rule assumes ~1.5" depth).
Bags needed: aquarium gravel is usually sold in 5 lb or 25 lb bags. You'd want roughly 3 × 25 lb bags to land at 75 lb (with the extra as safety stock).

For a planted version of the same tank at 3 inches: the volume jumps to 1.08 cuft → ~98 lb → 4 × 25 lb bags.

Aquarium Gravel Calculator