💡 Grow Light DLI Calculator
Enter your grow light's intensity (PPFD) and hours per day to get the Daily Light Integral, and see which plants it suits.
Daily Light Integral (DLI)
15.1 mol/m²/day
suits: Leafy greens & herbs
Typical target DLI
| Low-light foliage / houseplants | 3–6 mol/m²/day |
| Seedlings / young plants | 6–10 mol/m²/day |
| Leafy greens & herbs | 12–17 mol/m²/day |
| Fruiting (tomato, pepper) | 20–30 mol/m²/day |
DLI = PPFD × hours × 3,600 ÷ 1,000,000 — the total moles of light photons per m² per day. PPFD is on your grow light's spec sheet at a given distance. Target ranges are general horticulture guidelines. 🔒 In your browser.
How the grow light dli calculator works
The Daily Light Integral (DLI) is the total amount of usable light a plant gets per day, in moles of photons per square metre. It's the light intensity (PPFD, in µmol/m²/s) times the number of seconds of light per day, converted to moles: DLI = PPFD × hours × 3,600 ÷ 1,000,000. The tool compares your result with typical target ranges.
PPFD is listed on a quality grow light's spec sheet at a stated distance, and falls off quickly as you move the light away. Target ranges are general horticulture guidelines: low-light foliage is happy around 3–6, seedlings around 6–10, leafy greens 12–17, and fruiting crops like tomatoes want 20 or more.
Frequently asked questions
What is DLI (Daily Light Integral)?
The total number of photosynthetically-active photons that land on a square metre over a whole day, measured in moles (mol/m²/day). It combines light intensity and duration into one number that predicts plant growth.
How do I calculate DLI?
DLI = PPFD (µmol/m²/s) × photoperiod (hours) × 3,600 ÷ 1,000,000. For 300 PPFD over 14 hours: 300 × 14 × 3,600 ÷ 1,000,000 ≈ 15.1 mol/m²/day.
What DLI do my plants need?
Roughly: low-light houseplants 3–6, seedlings 6–10, leafy greens and herbs 12–17, and fruiting plants like tomatoes and peppers 20–30 mol/m²/day. Match your light's DLI to the crop.
What is PPFD?
Photosynthetic Photon Flux Density — the intensity of usable light hitting a surface, in µmol/m²/s. It's measured at a specific distance from the light and drops sharply as the distance increases.
How can I increase the DLI?
Raise the intensity (move the light closer or use a stronger fixture) or extend the photoperiod. Both increase the daily total — but respect each crop's needs, as too much light or too long a day can stress some plants.