Daily Light Integral

Updated by Travis Bates

The Daily Light Integral model uses measured PAR (Photosynthetically Active Radiation) to calculate an accumulated daily light integral. The time period resets daily at midnight.


Daily Light Integral is the total number of photosynthetically active photons that impinge upon 1 m2 surface area over a 24 hour period.  A good way to think of DLI is the total amount of radiation that is available for plant growth in a given day.


The photosynthetic photon flux density (PPFD) is measured by the QSO-S PAR Photon Flux sensor in units of μmol m-2 s-1.  This instantaneous value is averaged over the measurement interval by the data logger.

DLI (μmol m-2) = ∑(total mols per square meter in a 24 hour period)

DLI is typically reported in mols m-2.

DLI mols m-2= DLI ((μmol m-2) / 1,000,000

Compatible Sensors

New DLI chart
  • Click the Environmental model icon.
  • Select Daily Light Integral.
  • Enter a name for the model.
  • Enter a name for the chart.
  • Click Create to save the chart.

ZENTRA Cloud will auto-detect an appropriate PAR measurement for the input. If there are multiple PAR measurements specify the desired input from the sensor inputs drop-down.

(Example: Daily light integral).

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