Grow Light CheckFree grow-light calculator
Will this light work for your plants?
Grow Light Check turns published lamp specifications into a practical starting distance, estimated PPFD and DLI, and a clear explanation of what is known or assumed.
Published and reviewed by Grow Light Check · Updated
What the calculator checks
Usable output
Published PPFD, PPF or PPE is preferred. For ordinary white LEDs, lumens can support a wider estimate when stronger photometric evidence is unavailable.
Light distribution
Beam angle, fixture shape, emitting dimensions and distance determine how concentrated the light is at the leaves.
Plant requirements
The estimate is compared with broad, practical PPFD and daily-light ranges for houseplants and specialty growing uses.
Information that improves an estimate
| Specification | Why it matters |
|---|---|
| PPFD at a stated distance | Anchors the estimate to an actual plant-level reading. |
| PPF or PPE | Describes photon output more directly than lumens. |
| Actual watts | Supports PPE calculations; “equivalent watts” does not. |
| Beam angle or fixture size | Helps estimate concentration and coverage. |
Use the result as a starting point
A listed wattage is electricity use, not plant-level brightness. Reflectors, lenses, fixture dimensions, spectrum, barriers, and the illuminated area all affect the result. Manufacturer PPFD maps or a reading from a cosine-corrected quantum meter are stronger evidence than wattage alone.