LAI Calculator

"LAI" (Leaf Area Index) is simply how many square metres of leaf sit above each square metre of floor. An LAI of 3 means, on average, three layers of leaf between the lamp and the ground. It tells you whether your canopy is thin enough to waste light on bare floor, or so thick that lower leaves are shaded and airflow suffers. The tool also uses the Beer-Lambert light law (with your extinction coefficient) to estimate what fraction of light the canopy actually captures.

When tuning planting density, spacing, or pruning for a canopy-forming crop — leafy greens, tomatoes, cannabis, most vegetables. Estimate total leaf area from a few sampled plants scaled by plant count. Use it to decide whether to plant tighter, defoliate, or leave things alone. Less meaningful for widely spaced single specimens.

For most crops an LAI of about 3–5 is the sweet spot — enough leaf to intercept nearly all the light without heavy self-shading. Light Interception (%) shows how much light the canopy catches: below ~90% you are spilling light onto the floor (grow denser); pushed very high with a large LAI you may be shading lower leaves. Canopy Status turns this into a plain call — "Sparse: increase density," "Optimal," or "Dense: prune for airflow." Adjust spacing or pruning and re-run to watch LAI move into the 3–5 band.