Grow Light Calculator: PPFD & DLI
Turn your grow light’s wattage and footprint into the metrics that actually drive crop growth—canopy PPFD ($mutext{mol/m}^2/text{s}$) and Daily Light Integral (DLI). Find out exactly how many photoperiod hours to run your fixture for peak yields.
- Open PAR physics equations
- Runs 100% in-browser
- Peer-reviewed crop DLI targets
Calculate Your Light
Enter your light fixture and grow space specifications below.
Your Light Levels
Fill in your light specifications and click Calculate PPFD & DLI to see your delivered light levels.
How the Grow Light Calculator Works
Three steps convert raw electrical wattage into canopy light delivery.
1. Electrical Efficacy (PPF)
Fixture wattage multiplied by lamp photon efficacy ($mutext{mol/J}$) determines total photon emission per second ($text{PPF}$).
2. Canopy Area Density (PPFD)
Total PPF divided by grow space area in square meters (adjusted for reflector loss) yields average canopy photon flux density ($text{PPFD}$).
3. Photoperiod Duration (DLI)
$text{PPFD} times text{photoperiod hours} times 0.0036 = text{Daily Light Integral (DLI)}$, reflecting total moles of photons received daily.
DLI Targets & Fixture Efficiency Reference
Recommended daily light integrals by crop, plus efficiency baselines across lighting technologies.
| Crop | Target DLI (mol/m²/day) |
|---|---|
| Microgreens & Seedlings | 10–15 DLI |
| Leafy Greens (Lettuce, Kale) | 15–20 DLI |
| Culinary Herbs (Basil, Mint) | 15–25 DLI |
| Strawberries | 20–30 DLI |
| Bell Peppers | 25–35 DLI |
| Tomatoes | 25–40 DLI |
| Cucumbers | 25–40 DLI |
| Eggplant (Vegetative) | 25–40 DLI |
| Melons (Fruiting) | 40–65 DLI |
| Light Type | Efficacy (µmol/J) |
|---|---|
| LED (High-End) | 2.7–3.1 µmol/J |
| LED (Typical) | 2.2–2.6 µmol/J |
| LED (Budget) | 1.8–2.1 µmol/J |
| CMH / Ceramic Metal Halide | 1.4–1.6 µmol/J |
| HPS / High Pressure Sodium | 1.2–1.5 µmol/J |
| Fluorescent T5 | 0.7–0.9 µmol/J |
Frequently Asked Questions
What is DLI in indoor farming?
Daily Light Integral (DLI) measures the total moles of photosynthetically active photons delivered to one square meter of crop canopy over 24 hours ($text{mol/m}^2/text{day}$). DLI combines light intensity ($text{PPFD}$) with photoperiod duration ($text{hours}$), making it the single most accurate metric for crop light planning.
What is the difference between PPF and PPFD?
PPF (Photosynthetic Photon Flux) measures total photon emission rate from a lamp in $mutext{mol/s}$. PPFD (Photosynthetic Photon Flux Density) measures photon concentration landing on a specific area of plant canopy in $mutext{mol/m}^2/text{s}$. PPF is a rating of the lamp; PPFD depends on mounting height and grow area footprint.
How do I convert PPFD to DLI?
Multiply PPFD by photoperiod operating hours, then by $0.0036$. Formula: $text{DLI} = text{PPFD} times text{hours} times 0.0036$. Example: $350 mutext{mol/m}^2/text{s} times 16 text{ hrs} times 0.0036 = 20.16 text{ mol/m}^2/text{day}$.
What PPFD do my crops require?
Leafy greens and microgreens thrive at $200text{–}300 mutext{mol/m}^2/text{s}$. Fruiting crops like tomatoes and bell peppers prefer 400-600 μmol/m²/s. High-light melons in fruiting can utilize 700-1100 μmol/m²/s (supplemental CO₂ required above 900 μmol/m}^2/text{s}$).
Why are LED grow lights superior to HPS?
Modern LEDs achieve photosynthetic efficacies of $2.2text{–}3.1 mutext{mol/J}$, converting double the electricity into usable PAR light compared to HPS ($1.2text{–}1.5 mutext{mol/J}$). This drastically reduces power costs and heat management demands.
Disclaimer: These are planning estimates based on typical fixture efficiencies. Actual PPFD depends on hanging height, spectrum, and reflector design. © MistCulture.com