Two figures in, a clear answer out. The daily light integral (dli) calculator uses light hours per day and photon flux density (ppfd) to produce daily light integral (dli), applying the standard relationship for this problem in the order the calculation actually needs it.
What Is the Daily Light Integral (DLI) Calculator?
The daily light integral (dli) calculator works out daily light integral (dli) from light hours per day and photon flux density (ppfd).
Biological relationships are usually approximations rather than exact laws, so the output is best treated as an estimate with a sensible range around it.
How the Daily Light Integral (DLI) Calculation Works
The calculation applies the relationship as published, step by step, so each intermediate value can be checked against the underlying theory.
Keep the units consistent throughout. Mixing a percentage with a proportion is the single most common source of an answer that is out by a factor of a hundred.
Assumptions Worth Knowing
Any relationship used here assumes a constant rate, a representative sample, or a stable population. Real populations rarely meet those conditions for long, so treat the answer as a guide.
Where the inputs are field measurements, a single misread value can shift the result noticeably. Measure carefully and record what you used.
A Worked Example
Working through an example, with light hours per day set to 10, photon flux density (ppfd) set to 5, the calculator returns daily light integral (dli) of 0.18. Substitute your own figures and the same steps produce the same kind of answer.
Frequently Asked Questions
What do I need to work out daily light integral (dli)?
Enter light hours per day and photon flux density (ppfd). The calculator then works through the relationship and reports daily light integral (dli).
What does the daily light integral (dli) actually calculate?
It takes light hours per day and photon flux density (ppfd) and converts them into daily light integral (dli) using the standard relationship for this problem. Each step is applied in turn, so every output is traceable back to the numbers you typed in.
How should I enter light hours per day?
Use the value you actually have, in the unit shown next to the field. Enter every value in the same unit system. The calculator assumes the figures you supply are consistent, so it cannot correct a mistake that happens before the calculation starts.
Can I use this for a quick estimate as well as a precise answer?
Yes. The calculator is built for quick checks, so round your inputs to a sensible number of significant figures and the result will be just as useful. If you need more precision, keep the same method and add digits to the inputs rather than adjusting the method itself.
Is the answer exact?
It is as exact as the formula and the inputs allow. The method itself is the standard one for this problem, so the only sources of error are the figures you enter and the precision you ask for.