Aquarium Calculator & Fish Tank Planner

Measure the internal length, width, and height of your tank in centimetres, then use the formula: Volume (litres) = L × W × H ÷ 1000. For non-rectangular shapes such as bowfront or hexagonal tanks, our aquarium calculator adjusts the base-area formula automatically. Subtract substrate displacement (gravel or sand depth × base area) to get the net water volume available for fish and filtration.

Enter your tank's length, width, and height into the fish tank gallon calculator. The tool computes gross volume in litres first, then converts: 1 US gallon = 3.785 L. A standard 60 × 30 × 36 cm tank is approximately 65 litres or 17.2 US gallons. Remember that substrate and decorations reduce this figure by 10–20% in a planted setup.

Always measure the inside (interior) dimensions. Glass panels add 6–19 mm per side depending on thickness. Measuring exterior dimensions and then subtracting twice the glass thickness for each dimension gives the true water volume. Our calculator includes a glass-offset field that performs this correction automatically.

For a bow-front aquarium, the calculator uses the trapezoid approximation: base area = ((front width + back width) / 2) × depth. For a hexagonal prism tank, the formula is: base area = (3√3 / 2) × s², where s is the flat-to-flat width divided by √3. Select the matching shape in our aquarium size chart calculator and enter the requested dimensions — the correct formula is applied automatically.

Manufacturers state gross nominal volume measured from outside edges at full depth. In practice, glass thickness, substrate (gravel or sand), rocks, driftwood, filter equipment, and an air gap below the waterline all displace water. A well-planted 100-litre (26 gal) aquarium may hold only 70–80 litres of actual water. Use our fish tank water capacity calculator with the substrate offset to get the true net volume.

For a rectangular aquarium, multiply Length × Width × Height (in cm) and divide by 1,000 to get volume in litres. To convert litres to US gallons, multiply by 0.264172 (or divide cubic inches by 231).

Gross volume is the maximum external capacity of the empty glass shell. Net water volume is the actual amount of liquid in the tank after accounting for glass thickness, the top headroom gap (~1 cm fill line), and displacement from substrate and rocks.

For a bowfront tank, calculate the rectangular base area plus the parabolic curve area: (L × W) + (2/3 × L × bow depth) multiplied by height. For a cylinder tank, use π × radius² × height.

Glass thickness for aquariums is calculated using the plate-bending formula: t = √(SP × h² / (0.75 × E)), where SP is water pressure, h is the longest unsupported panel height, and E is the allowable bending stress for glass (~19 MPa with a safety factor of 3.8). Our aquarium glass thickness calculator outputs the minimum recommended thickness in millimetres, then rounds up to the nearest standard glass size (4, 5, 6, 8, 10, 12, 15, 19 mm).

The safety factor divides the allowable bending stress used in the thickness formula. A factor of 3.8 is the DIY and rimless standard (recommended default). Use 4.0 for extra conservatism on large rimless builds, 3.0 for fully braced Euro-brace tanks, and 2.5 only for smaller braced tanks where deflection is mechanically constrained. A higher safety factor results in a thicker — and safer — glass recommendation.

Yes. Without a top frame or cross-brace to distribute hydrostatic pressure, each glass panel in a rimless build bears the full bending load from water. Our how thick glass for aquarium calculator automatically applies the higher safety factor of 3.8–4.0 for rimless builds versus 2.5–3.0 for braced tanks, which typically results in 2–4 mm thicker panels for the same tank dimensions.

Acrylic deflection is calculated using the same plate-bending equations, but with acrylic's Young's modulus (~3 GPa vs. glass's ~70 GPa). This means acrylic flexes significantly more for the same thickness. Our calculator outputs the expected panel deflection (bow) in millimetres. For acrylic tanks, the maximum recommended deflection is L/250, where L is the panel's long edge, to avoid permanent deformation or silicone joint stress.

Glass thickness depends on water height and panel length. For a standard 60 cm long by 36 cm high rimless tank, 6 mm float glass with a safety factor of 3.8 is standard. Taller tanks (over 50 cm) require 10 mm to 12 mm glass to prevent bowing deflection and failure.

Use the aquarium gravel calculator formula: substrate volume (L) = base area (cm²) × depth (cm) ÷ 1000. Then multiply by bulk density: coarse gravel ≈ 1.5 kg/L; sand ≈ 1.6 kg/L; aqua soil ≈ 0.65 kg/L. A 60 × 30 cm base with 5 cm of gravel needs 9 litres or about 13.5 kg. Our how much sand for aquarium calculator handles all substrate types and slope configurations.

For a sloped substrate bed, the calculator averages front and back depths: Volume = base area × ((front depth + back depth) / 2). For example, a 60 × 30 cm tank with a 2 cm front slope and 8 cm back yields a volume of 60 × 30 × 5 cm (average) = 9 litres of soil. Enable the slope toggle in the substrate section and enter front and back depths individually.

Total weight = (tank dry weight) + (water volume × 1 kg/L) + (substrate kg) + (rock & driftwood kg) + (equipment kg). Water weighs 1 kg per litre (8.34 lb per US gallon). A 200-litre (53 gal) tank with substrate and rocks typically weighs 250–280 kg (550–620 lb) when filled. Always verify your stand and floor rating against this total loaded weight before setting up a large aquarium.

Residential floors in most modern homes are rated for 200–400 kg/m² (40–80 lb/ft²). A 200-litre filled aquarium concentrates roughly 250–280 kg over the footprint of its stand (~0.18 m²), equalling ~1,400 kg/m². Position the stand against a load-bearing wall, run it perpendicular to floor joists, or use a purpose-built aquarium stand rated for the total loaded weight. For tanks over 400 litres, consult a structural engineer.

Rock displaces approximately its own volume in water: 1 kg of average aquarium rock ≈ 380 mL. Driftwood is variable; waterlogged wood displaces very close to its own volume (~1 L per kg), while dry driftwood first floats before sinking after waterlogging. Measure rock displacement by the water-level rise method: fill a bucket to a known mark, add the rock, and measure the rise. Our aquarium weight panel lets you enter a total rock/decoration displacement offset in litres.

A filled fish tank weighs approximately 10 to 12 pounds per gallon (1.2 to 1.4 kg per litre) when including water, glass, substrate, and rocks. For example: a 10-gallon tank weighs ~110 lbs (50 kg), a 20-gallon long weighs ~220 lbs (100 kg), a 55-gallon tank weighs ~625 lbs (285 kg), and a 75-gallon tank weighs ~850 lbs (385 kg).

For a standard 2-inch (5 cm) substrate depth, plan on 1.5 to 2 pounds of gravel or sand per gallon of tank volume. Calculate exact substrate volume in litres by multiplying tank Length × Width × Desired Depth (in cm) and dividing by 1,000.

Most modern residential floors support aquariums up to 55–75 gallons (under 900 lbs) without structural reinforcement, especially if placed perpendicular to floor joists against a load-bearing wall. Tanks exceeding 100 gallons (>1,200 lbs) should be placed on a ground-floor slab or verified by a structural engineer.

Adding rocks increases total tank weight while displacing water. Because dense rocks like Seiryu (2.7 kg/L) weigh more than the water they displace (1 kg/L), heavy rock aquascapes increase net load by 1.7 kg for every litre of displaced water.

Use our how many fish in aquarium calculator, which uses a bioload scoring system rather than the simplistic inch-per-gallon rule. Each species is assigned a bioload score based on body shape, adult size, diet, and waste output. The target is ≤100% of the tank's calculated bioload capacity, with a warning threshold at 80%. A 60-litre tank can safely hold a bioload score of up to 60 points — for example, 8 ember tetras (0.5 pt each) plus 6 pygmy corydoras (1 pt each) = 10 points total, well within capacity.

No — the 1 inch per gallon rule is a rough and often misleading heuristic developed for small community fish in the 1950s. It fails for wide-bodied fish (goldfish, cichlids), tall fish (discus, angelfish), and high-waste species. Modern fishkeeping uses bioload scoring, surface area, and filtration turnover rate as more accurate stocking metrics. Our fish tank gallon calculator uses per-species bioload coefficients for 125+ species.

Bioload capacity is primarily determined by the nitrogen cycle efficiency of your filtration and the dissolved oxygen levels at your water's surface. As a guideline, our calculator assigns a capacity of 1 bioload point per litre of net water volume. Each species entry has a pre-set bioload coefficient (light, moderate, or heavy). Heavy bioload fish like goldfish or large cichlids rate 3–5× higher than similar-sized tetras.

Yes. Live plants consume ammonia and nitrate directly as plant fertiliser through the nitrogen cycle, reducing the biochemical oxygen demand on your filter. A heavily planted tank (>50% plant coverage) can support approximately 20–30% more bioload than an equivalent unplanted tank. Our calculator applies a plant bonus modifier to bioload capacity when you select plants in the Plant Planner tab.

Our compatibility checker evaluates three parameters for every fish combination in your stocking list: (1) temperature overlap — all species' minimum–maximum ranges must intersect; (2) pH overlap — all pH ranges must share a common value; (3) aggression flags — species tagged as fin-nippers, territory-holders, or predators trigger warnings against vulnerable tank-mates. Conflicts are highlighted in the Biological Parameter Check panel with specific species callouts.

The number of fish depends on your tank volume, species bioload, and filtration capacity. The old '1 inch per gallon' rule is inaccurate. Use a metabolic bioload calculator that factors in body mass, metabolic rate, and waste output. A 20-gallon tank can hold 10–15 small tetras or 2–3 medium cichlids, depending on species.

Bioload is the total biological waste produced by all fish and invertebrates in your tank. It includes ammonia from respiration and uneaten food. Higher bioload requires more filtration and more frequent water changes. Bioload scales exponentially with fish size — a 6-inch Oscar produces roughly 20x the waste of a 1-inch Neon Tetra.

Check three key parameters: temperature range overlap, pH range overlap, and aggression compatibility. Schooling fish need minimum group sizes (typically 6+). Avoid housing large predatory fish with small nano species. Use an aquarium fish compatibility checker that screens for temperature, pH, and predation conflicts automatically.

Aim for 60–80% bioload capacity for a balanced, low-maintenance tank. Going above 80% increases ammonia spikes and requires more water changes. Below 40% is very conservative and ideal for beginners. The aquarium stocking calculator shows your real-time bioload percentage based on the species you select.

Yes. Live plants absorb ammonia, nitrites, and nitrates, acting as secondary biological filtration. Fast-growing stem plants like Rotala and Hygrophila can increase your effective stocking capacity by up to 50%. Add plants from the CO2 calculator to see the bioload bonus reflected in the stocking calculator.

Use our aquarium heater calculator: Wattage = Net Volume (L) × ΔT (°C) × 0.238. ΔT is the difference between your target tank temperature and the minimum ambient room temperature. A 100-litre tank targeting 26°C in a room that drops to 20°C (ΔT = 6°C) needs 100 × 6 × 0.238 ≈ 143 W. Always size up to the next standard heater wattage for headroom and redundancy.

The watts-per-gallon guideline is 2.5–5 W/US gallon for most tropical tanks. The lower end (2.5 W/gal) applies to smaller temperature differentials (ΔT ≤ 5°C), while the upper end (5 W/gal) applies to tanks in cold rooms or species needing high temperatures (28–30°C). Our aquarium heater calculator uses the precise thermal formula rather than a flat W/gallon estimate, which is more accurate across a wider range of tank sizes and room conditions.

As a rule of thumb, you need 3 to 5 watts per gallon (0.8 to 1.3 watts per litre) of water for a standard temperature increase of 5°C to 10°C (9°F to 18°F) above ambient room temperature. A 20-gallon tank typically requires a 50W to 75W heater, while a 55-gallon tank requires a 150W to 200W heater.

Heater wattage is calculated based on tank volume and temperature differential (ΔT = Target Temp − Room Temp). Formula in US units: Watts = Volume (gallons) × ΔT (°F) × 0.5. Formula in metric: Watts = Volume (litres) × ΔT (°C) × 0.238.

For tanks requiring over 150W to 200W, using two smaller heaters (e.g., two 100W heaters instead of one 200W) is highly recommended for redundancy. If one heater fails off, the second keeps the tank warm enough. If one heater sticks on, a single smaller unit cannot overheat the entire tank to lethal levels.

Position the heater horizontally or at a 45-degree angle near strong water circulation, such as right next to the filter outlet or powerhead. Good water flow prevents localized hot spots and ensures heat is evenly distributed across the entire aquarium.

Yes, our aquarium heater size calculator supports both UK/metric (litres and Celsius) and US imperial (gallons and Fahrenheit) units. You can toggle your preferred unit system anytime.

The recommended filter turnover rate is: Flow Rate (L/h) = Net Volume × Turnover Multiplier. Use 4× turnover for lightly stocked community tanks, 6× for moderately stocked tanks, 8–10× for heavily stocked or high-bioload setups, and 10–15× for cichlid tanks or sumps. Our filter flow rate calculator derives the multiplier dynamically from your stocking bioload rating and plant settings, then outputs the target L/h or GPH rating to look for when purchasing a filter.

Calculate required flow rate (in GPH or L/h) by multiplying your net tank volume by the recommended turnover multiplier. For example, a 30-gallon community tank with a 6x turnover recommendation requires a filter rated at minimum 180 GPH (680 L/h).

Recommended hourly turnover rates vary by filter hardware and bioload: Sponge filters need 3–4x hourly volume turnover, Hang-On-Back (HOB) power filters need 5–7x, Canister filters need 6–8x, and high-tech planted or marine reef systems need 10–12x.

Yes. Higher bio-density produces more ammonia and organic waste. For heavy stocking (>80% bioload capacity), increase your target turnover rate by 2x to maintain adequate water oxygenation and biological conversion speed.

Select a canister filter with a flow rate rated at 6x to 8x your tank volume per hour, and choose a model that holds 5% to 10% of your tank volume in biological media (e.g. ceramic rings or matrix stone).

CO2 bubble rate depends on tank volume, plant density, and diffusion efficiency. A common starting point is 1 bubble per second per 50 litres for a medium-tech planted tank. Our CO2 calculator determines your target dissolved CO2 concentration (ideally 15–30 ppm for high-tech plants) from your pH and KH readings using the formula: CO2 (ppm) = 3 × KH (dKH) × 10^(7 − pH). The plant planner then recommends a bubble rate in bubbles-per-second based on your plant selection and tank volume.

Dissolved CO2 is calculated using the Henderson-Hasselbalch carbon equilibrium formula: CO2 (ppm) = 3.0 × KH (dKH) × 10^(7.0 − pH). For example, at pH 6.8 and 4 dKH, the dissolved CO2 concentration is approximately 24 ppm.

The optimal CO2 concentration for high-tech planted tanks is 15 to 30 ppm. Levels below 15 ppm limit plant growth and encourage algae, while levels exceeding 40 ppm can suffocate fish.

Bubble rate depends on tank volume, plant density, and diffusion efficiency. As a baseline: a 20-gallon planted tank needs approximately 1 bubble per 2–3 seconds (0.3–0.5 BPS), while a 55-gallon tank requires 1 to 2 bubbles per second. Always monitor drop checkers and pH-KH values when adjusting bubble rates.

Low-light plants (Java Fern, Anubias) require 15–30 µmol/m²/s PAR at substrate depth. Medium-light plants (Crypts, Stem plants) need 30–50 PAR. High-light carpet plants (Monte Carlo, Dwarf Baby Tears) require >50 PAR and CO2 injection.

Weekly water change recommendation = bioload density × base rate. At low stocking (≤40% bioload): 10–15% weekly. At moderate stocking (40–70%): 20–25% weekly. At high stocking (>70%): 30–50% weekly. Our weekly water change estimator adjusts this using your actual stocking list bioload score, plant modifier, and pre-change nitrate level from the Interactive Nitrate Simulator, giving you a personalised volume in litres or gallons to remove and replace each week.

Most freshwater aquariums require a 20% to 30% water change weekly or bi-weekly to maintain nitrates below 20 ppm. Heavily stocked tanks or goldfish setups may require 30% to 50% weekly water changes.

Nitrate dilution is calculated using the formula: Post-Change Nitrate = Pre-Change Nitrate × (1 − Change Fraction) + Tap Water Nitrate × Change Fraction. For example, a 50% water change on a 40 ppm tank with 0 ppm tap water results in 20 ppm nitrate.

Keep nitrates below 20 ppm for optimal fish health. Levels between 20 ppm and 40 ppm are tolerable for hardy community fish, but levels above 40 ppm cause chronic stress, suppress growth, and promote algae blooms.

If your tap water contains background nitrates (e.g. 10–20 ppm), water changes alone cannot lower tank nitrates below that tap baseline. You can use live aquatic plants to absorb nitrates or mix tap water with RO/DI (reverse osmosis) purified water.

Dosage depends on your treatment goal: For general stress reduction and electrolyte support (Level 1), use 1 tablespoon per 5 gallons (1.5 g/L). For mild fungal infections, fin rot, and nitrite poisoning protection (Level 2), use 1 tablespoon per 2.5 gallons (2.5 g/L). For severe external parasites like Ich (Level 3), use 1 tablespoon per 1 gallon (4.0 g/L). Always dissolve salt in a container of aquarium water before adding it gradually over several hours.

No, salt NEVER evaporates. Only pure water evaporates into the air, leaving all dissolved salt behind. If you top off an aquarium due to evaporation, add PURE fresh water with zero salt. You should only add replacement salt during physical water changes, dosing exclusively for the volume of new replacement water being added.

To treat Ich effectively: Dose aquarium salt to Level 3 (1 tablespoon per gallon / 4 g/L) over 24 to 48 hours. Simultaneously raise water temperature gradually to 86°F (30°C) if your fish tolerate it, which stops the parasite's life cycle. Maintain intense aeration with air stones because warm, salty water holds less dissolved oxygen. Continue treatment for a minimum of 10 to 14 days to eradicate all free-swimming theronts.

Caution is required. Scaleless fish (Corydoras, loaches, knife fish) and catfish have heightened sodium sensitivity — start with a half dose (maximum 1 tablespoon per 10 gallons) and monitor closely. Live aquatic plants (especially Hornwort, Anacharis, and Vallisneria) melt rapidly at salt concentrations exceeding Level 1. Freshwater snails and delicate shrimp are also intolerant of sustained salt treatment.

Do not use iodized table salt with anti-caking agents (like yellow prussiate of soda), as these additives are toxic to fish. Pure, non-iodized coarse kosher salt or canning salt is chemically identical to aquarium salt (pure NaCl). Epsom salt (magnesium sulfate, MgSO4) is chemically distinct and is used for relieving dropsy, swim bladder bloating, and severe constipation, not for parasite eradication.

A standard 55-gallon aquarium measures 48 inches long by 13 inches wide by 21 inches tall (122 × 33 × 53 cm). Because it is narrow (13 inches deep), it is best suited for fast-swimming schooling fish, but offers limited floor depth for intricate aquascaping compared to a 40-gallon breeder or 75-gallon tank.

The 40-gallon breeder measures 36″ L × 18″ W × 16″ H. Its 18-inch front-to-back depth provides 50% more floor footprint area than a 55-gallon tank (13 inches wide). This wide footprint allows for dramatic aquascaping depth, superior water-to-air oxygenation, and much more territory for bottom-dwelling fish like cichlids, corydoras, and plecos.

A 20-gallon long measures 30″ L × 12″ W × 12″ H, while a 20-gallon high measures 24″ L × 12″ W × 16″ H. The 20-gallon long is preferred by most experienced aquarists because its 30-inch length provides 25% more swimming runway and greater surface area for gas exchange, making it ideal for active schooling tetras and rasboras.

A 75-gallon aquarium weighs approximately 140 lbs (64 kg) empty. When filled with 75 gallons of water (625 lbs), 80 lbs of substrate, and decorations, the total operational weight reaches 850 to 900 lbs (385 to 410 kg). Verify that your stand and floor joists can handle this concentrated load.

Standard rimless sizes follow the Japanese/European dimensions: 45P (45×27×30 cm, 9.6 gal), 60P (60×30×36 cm, 17.1 gal), 90P (90×45×45 cm, 48 gal), and 120P (120×45×45 cm, 64 gal). They feature ultra-clear low-iron glass, clear silicone, and slightly thicker panels (6–12 mm) to withstand water pressure without plastic framing.

A standard 20–30 gallon community tank typically consumes 30 to 50 kWh per month, costing between $5 and $8 monthly at average US rates ($0.16/kWh). A 75-gallon high-tech planted or cichlid tank uses 100 to 180 kWh per month ($16 to $30 monthly), with the heater accounting for 60–75% of total power consumption.

The aquarium heater is by far the biggest energy consumer, responsible for 60% to 80% of total electrical draw in cooler months. High-output LED lighting ranks second (15–25%), while modern DC filter pumps and air pumps are extremely efficient, usually consuming only 5% to 10% of total power.

With an average duty cycle of 35% (running ~8.4 hours daily), a 100W heater consumes 0.84 kWh per day, or about 25.2 kWh per month. At an average electricity rate of $0.16 per kWh, it costs approximately $4.03 per month to operate.

1) Add a tight-fitting glass or polycarbonate lid — this reduces evaporative heat loss by up to 70%, dramatically cutting heater run time. 2) Insulate the back and sides of the tank with dark foam board. 3) Reduce photoperiod to 6–8 hours daily using high-efficiency LED lights. 4) Use an external digital temperature controller (like an Inkbird) to prevent thermostat hysteresis waste.

Start with the aquarium volume calculator to determine your exact water volume in gallons or litres. Knowing the net water volume is critical for sizing equipment, dosing medications, and planning fish stocking. Once you have your volume, use the fish tank weight calculator to verify your stand and floor can handle the loaded weight, then move to the aquarium stocking calculator to plan your fish community.

The glass thickness calculator in our volume tool determines the minimum safe glass thickness for your custom tank. Enter your tank dimensions, select rimless or braced build type, and choose glass type (standard float or tempered). The calculator applies the plate-bending formula with a safety factor of 3.8 for rimless builds and outputs the recommended thickness in millimetres. Always round up to the next standard glass size for safety.

Yes — the aquarium heater size calculator lets you set the minimum ambient room temperature, which is critical for tanks in cold basements or garages. A 100-litre tank in a 15°C room targeting 26°C needs significantly more wattage than the same tank in a 20°C room. The calculator factors this into the thermal formula and also suggests splitting wattage across two heaters for redundancy in cold environments.

For planted community tanks, the aquarium filter calculator recommends a turnover rate of 6× the net water volume per hour for a canister filter. This provides sufficient flow for nutrient distribution to plants while avoiding CO2 stripping. Heavily stocked planted tanks may need 8× turnover. The filter flow calculator adjusts the recommendation based on your bioload density and plant coverage.

Enter your tap water nitrate reading into the aquarium water change calculator. If your tap water nitrate exceeds 10 ppm, water changes become less effective at diluting tank nitrates because you are adding nitrate back in with the fresh water. The nitrate calculator aquarium tool simulates this effect and recommends alternative strategies such as increasing plant coverage, using RO water, or reducing feeding.

The aquarium CO2 calculator targets a dissolved CO2 concentration of 20–30 ppm for high-tech planted tanks. Use the pH KH CO2 chart to verify your levels: measure your pH and KH, then reference the chart. At KH 4 dKH and pH 6.8, dissolved CO2 is approximately 19 ppm. Adjust your CO2 bubble rate per second until you reach the target range, monitoring drop checker color and fish behaviour for safety.

A fully set up 55-gallon fish tank typically weighs 600–650 lbs (270–295 kg). This includes approximately 460 lbs of water (8.34 lbs per gallon), 78 lbs for the glass tank itself, 50–80 lbs for substrate (gravel or sand), and 20–40 lbs for rocks, driftwood, and equipment. Use the fish tank weight calculator to get a precise estimate for your specific tank dimensions, substrate choice, and hardscape.