PPFD to DLI calculator
Enter a PPFD reading and how many hours the light runs each day to get the Daily Light Integral (DLI). PPFD measures instantaneous intensity; DLI adds up the whole day into a single number you can compare against crop targets.
Formula: DLI = PPFD × 3600 × hours ÷ 1,000,000
Common crop DLI targets
These are commonly cited target ranges in mol/m²/day. Optimal DLI depends on the specific variety and growth stage, so treat them as starting points.
| Plant type | Target DLI (mol/m²/day) |
|---|---|
| Low-light foliage / houseplants | 2–6 |
| Seedlings and propagation | 6–12 |
| Lettuce, leafy greens, herbs | 12–17 |
| Fruiting vegetables (tomato, pepper, cucumber) | 20–30 |
| High-light greenhouse crops | 25–35 |
FAQ
What is DLI (Daily Light Integral)?
DLI is the total amount of photosynthetic light a plant receives in one day, measured in mol/m²/day. It combines light intensity (PPFD) with how many hours the light is on.
How do you calculate DLI from PPFD?
DLI = PPFD × 3600 × hours ÷ 1,000,000. Multiply PPFD by the number of seconds the light is on per day (3600 seconds per hour), then divide by one million to convert micromoles to moles.
The DLI formula itself is exact. Its accuracy depends entirely on your PPFD figure: if the PPFD came from a lux-based estimate rather than a quantum sensor, the resulting DLI carries that same uncertainty.
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