Grow Light Coverage Calculator
Estimate the area an LED grow light can cover from its actual wattage. Pick a growth stage to set a watts-per-square-foot target, or enter your own, and read coverage in square feet and square meters.
How to size grow light coverage
- Enter the actual power draw of the light in watts.
- Choose a growth stage, or enter your own watts per square foot.
- Read the coverage area in square feet and square meters.
Examples
600 W LED in flower
600 W, flowering (35 W/sq ft)
About 17.14 sq ft (1.59 sq m)
Frequently asked questions
How does this estimate coverage?
It divides the light wattage by a watts-per-square-foot target. The defaults are rough LED draw figures: 15 for seedlings, 25 for vegetative growth and 35 for flowering. You can override the target.
Should I use rated or actual wattage?
Use the actual power draw at the wall, not an inflated equivalent rating. Many LED fixtures are marketed with a much higher number than they really consume, which would overstate coverage.
Is watts per square foot accurate?
It is only a rough guideline. LED efficiency, mounting height and reflectivity all change real output, so two lights of equal wattage can light very different areas.
What about PPFD and DLI?
Measuring PPFD with a meter and targeting a daily light integral (DLI) is far more precise than a wattage rule. Use this tool for quick planning, then verify with light readings.
Does this work for non-LED lights?
The defaults assume LED draw. For HID or fluorescent fixtures the watts-per-square-foot relationship differs, so enter your own target value to match that technology.
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