Light and CO₂ are co-limiting factors — one without the other leaves yield on the table. This tool calculates your DLI, recommends CO₂ enrichment targets, and shows you the temperature and VPD your crop needs to make the most of both.
Photosynthesis needs light energy and CO₂ as a carbon source. When light is low, stomata are barely open and extra CO₂ just sits there. When light is high but CO₂ is ambient (400 ppm), the enzyme RuBisCO runs out of substrate and photosynthesis plateaus.
The sweet spot shifts by growth stage. This calculator maps your PPFD to the right CO₂, temperature, and VPD targets so both inputs are working in sync.
Daily Light Integral (DLI) is the total photosynthetic light your crop receives in a day, measured in mol/m²/day. It’s PPFD × hours, converted to moles.
DLI is a better predictor of yield and quality than PPFD alone, because it accounts for photoperiod. A shorter day at higher intensity can deliver the same DLI as a longer day at lower intensity — but with different physiological effects.
At low PPFD, the plant can’t use extra CO₂. Focus on raising light intensity before enrichment.
Stomata are active and light is sufficient. Supplemental CO₂ begins improving photosynthetic rate measurably.
Light is driving photosynthesis hard. CO₂ enrichment delivers clear yield gains — raise temps and VPD to match.
At peak PPFD, RuBisCO is starving for carbon. Maximizing CO₂ is essential to avoid plateauing.
Use the Light & CO₂ optimizer to find targets, or the Injection calculator to dose your room.
PPFD, DLI, CO₂, temperature, and VPD targets for every growth stage — one printable reference, always free.
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Read the guide