Free aquarium lighting calculator. Calculate required lumens and PAR values for your tank based on size, depth, and plant or coral requirements.
Aquarium lighting is the engine that drives photosynthesis, coloration, and even fish behavior, yet it is also the most common source of algae problems and plant failure when matched poorly to the tank. This calculator converts your tank footprint and intended plant or coral category into a recommended PAR target at substrate level, the lumens that practical LED fixtures must deliver, and an estimated wattage range. The goal is to give planted-tank keepers, reef hobbyists, and beginners alike a defensible starting point that they can refine with PAR meters or visual cues.
The model classifies your build into low, medium, or high light demand and uses tank length, width, and water depth to estimate the spread and penetration losses through water. It then applies industry PAR targets (roughly 30-50 micromol at substrate for low light, 50-80 for medium, and 80-150+ for high light or SPS corals), back-calculates the lumens needed at the surface assuming a typical 5500-7500K LED spectrum, and translates that into wattage for a generic high-efficiency fixture. Deeper tanks and densely shaded foregrounds will require higher surface output to compensate.
Enter your tank size and plant type to calculate required lumens, PAR values, and estimated wattage. Different lighting requirements apply for low, medium, and high light plants and corals.
Most tanks benefit from 8–10 hours of light per day. Too much light promotes algae; too little stunts plant growth. Use a timer to maintain a consistent photoperiod.
LED lights are more energy-efficient and longer-lasting than fluorescent tubes, making them more economical long-term. High-quality LEDs allow spectrum adjustment for optimal plant and coral growth.
PAR measures light useful for photosynthesis. Low-light plants need 20-50 PAR, medium-light need 50-100, high-light need 100+ PAR. Measure PAR at substrate level for accurate assessment.
Most planted tanks do well with 8-10 hours of light daily. Too little light slows growth; too much promotes algae. Use a timer for consistent photoperiod. Adjust based on plant growth and algae levels.
This calculator uses standard lumen and PAR guidelines. Actual light reaching plants depends on water clarity, tank depth, and light angle. Use a PAR meter for precise measurement.
LED lights are energy-efficient and customizable. Fluorescent lights are affordable but less efficient. Metal halide lights are powerful but generate heat. Choose based on tank type and budget.
Regular household lights lack the spectrum for plant growth. Use aquarium-specific lights with appropriate color temperature (5000-7000K for plants). Avoid incandescent lights due to heat generation.