What this calculator does
Daily light integral (DLI) works out total photosynthetic light a plant receives per day, from light intensity and photoperiod. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
The inputs explained
| Field | What to enter |
|---|---|
| Photosynthetic photon flux density (PPFD) (µmol/m²/s) | A number, measured in µmol/m²/s. Starts at 400. |
| Photoperiod (hours/day) | A number, measured in hours/day. Starts at 12. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with photosynthetic photon flux density (ppfd)
Every other input is held at the calculator’s starting values while photosynthetic photon flux density (ppfd) varies. Select any row to load that scenario into the calculator.
| Photosynthetic photon flux density (PPFD) (µmol/m²/s) | Daily light integral | Photon flux over the day | PPFD used |
|---|---|---|---|
| 200 | 8.64 mol/m²/day | 8,640,000 µmol/m² | 200 µmol/m²/s |
| 300 | 12.96 mol/m²/day | 12,960,000 µmol/m² | 300 µmol/m²/s |
| 400 | 17.28 mol/m²/day | 17,280,000 µmol/m² | 400 µmol/m²/s |
| 600 | 25.92 mol/m²/day | 25,920,000 µmol/m² | 600 µmol/m²/s |
| 800 | 34.56 mol/m²/day | 34,560,000 µmol/m² | 800 µmol/m²/s |
| 1,200 | 51.84 mol/m²/day | 51,840,000 µmol/m² | 1,200 µmol/m²/s |