Daily Light Integral Calculator
Convert light intensity and photoperiod into daily light integral, the figure plants actually respond to.
Intensity and duration trade off, up to a point
The same DLI can come from bright light for a short day or dimmer light for a long one, and for most crops the total matters more than the split. The exception is photoperiod-sensitive species, where day length itself triggers flowering — running 20 hours of dim light to hit a DLI target will keep a short-day plant vegetative indefinitely.
What this page needs from you
This page asks for light intensity (ppfd) in µmol/m²/s and hours of light in h. From those it returns daily light integral in mol/m²/day, together with target for leafy greens, target for tomatoes, hours needed for dli 20 and ppfd needed for dli 20 in 14 h. Every figure updates as you type, and nothing you enter leaves your browser.
Rates are regional, and local advice beats a general figure
Soil type, rainfall, variety and season change the right answer more than the arithmetic does. Use this to plan and to check an order, and check the figure against your local extension service, agronomist or supplier before committing to a whole field.
The formula
DLI = PPFD × hours × 3600 ÷ 1,000,000
Every result on this page comes from this formula. Nothing is rounded until the final display, so figures match a spreadsheet to the cent.
How to use the Daily Light Integral Calculator
- Fill in each field with your own figures — the defaults are only there as an example.
- The result updates as you type, so there is no button to press.
- Check the breakdown under the main result for the supporting numbers.
- Use the copy button to take the result with you, or share the link to reload the same inputs.
Daily Light Integral Calculator — frequently asked questions
Is this daily light integral calculator free to use?
Yes. Every calculator on the site is free, needs no sign-up, and runs entirely in your browser, so your figures never leave your device.
How accurate is the result?
The maths is exact for the formula shown on the page. Accuracy in the real world depends on your inputs and on assumptions the formula cannot see, so treat the output as a well-grounded estimate rather than a quote.
Can I use it on my phone?
Yes. The page is responsive, weighs a few kilobytes and works offline once loaded, so it behaves the same on a phone as on a desktop.
What people search for
This page answers each of these searches. They are the exact phrases visitors use to find the daily light integral calculator.
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About this calculator
Written and reviewed by The Samsung Calculator editorial team. Every calculator is written against a published formula, reviewed against at least one independent reference implementation, and dated when it changes.
Last reviewed September 14, 2026 · Calculation runs client-side · No data collected · Report an error