DLI is daily light integral and is the amount of light a plant can handle in 24h in its current stage. PPFD is the light intensity a plant can handle in its current stage.
PPFD Seedlings: 150 - 300 umols
PPFD Vegetative: 300 - 600 umols
PPFD Flowering: 600+ mols
So depeding how many umols you throw at your plant multiplied by the hours per day you get your dli. This might come in handy to do the math:
Quantum Sensors measure measure the instantaneous photosynthetic photon flux density in µmol m-2 s-1. Use Calculator below to convert instantaneous PPFD µmol m-2 s-1 to DLI photosynthetic photon flux density in mol m-2 d-1 Enter PPFD : Enter Hours : DLI:
horticulturelightinggroup.com
So lets say you are throwing 200 umols at a seedling for 18h a day that gives you an DLI of about 13. What the max dli per grow stage is depends on a lot of factors like strain, temperature, humidity, how much water a plant gets, co2 concentration in the grow area. You can find research papers on the net to give you some ideas.
For me in my grow environment seedlings do great at a dli of 10-15. vegetative does best at about 20 and in flower the max they can handle is 35 before showing sings of stress. These numbers may apply to your environment to some degree for seedling and vegetative stage but might go higher in flower.