Light & energy
Grow light calculator.
DLI & Grow Light Calculator
Turn measured light intensity and a lighting schedule into a daily light budget. Explore intensity, hours and electricity use together.
Enable JavaScript to calculate from your inputs.
Add up a changing day.
Each line: measured PPFD, duration in hours. Periods must not overlap and the total must fit within 24 hours.
Make the result
mean something.
How to use Grow light calculator
- Enter PPFD measured at leaf height, not the lamp wattage or an uncalibrated lux estimate.
- Set the light duration and your chosen DLI comparison target. Lamp power means actual electrical draw.
- Explore the comparison grid or add several measured periods to sum a variable day.
A worked example
At 200 µmol/m²/s for 16 hours, the daily light integral is 11.52 mol/m²/day. A 100 W lamp running for 16 hours uses 1.6 kWh. These are illustrative inputs, not crop prescriptions.
Assumptions and scope
The constant-light model assumes the entered PPFD reaches the leaves throughout the period. DLI requirements and suitable photoperiods vary by crop and growth stage. Lux-to-PPFD conversion depends on the spectrum and is deliberately not treated as universal.
Primary method or data reference ↗
Results use the entered values and the method described here. Keep units, sampling conditions and the source of the data with your interpretation.