מחשבון מרחק תאורת גידול

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Canopy intensity comes straight from the inverse-square law: I₂ = I₁ × (d₁ ÷ d₂)². Enter the PPFD your fixture is rated at (1200 µmol/m²/s by default), the distance that rating was measured at (12), and the distance to your canopy (18), and the result is 533 µmol/m²/s. The table re-runs the same equation at 6, 12, 18, 24 and 36 units of distance, converting each figure to approximate lux by multiplying PPFD by 54.

The reference pair drives everything, so take the PPFD number and the distance it was quoted at from the same line of the manufacturer's PAR map; guessing that distance skews the answer quadratically. Growth stage then sets the target band, either Seedling 200–400, Vegetative 400–600 (the default) or Flowering 600–1000 PPFD, and when you fall outside it the tool solves d = d₂ × √(I₂ ÷ target) for the distance that hits the band midpoint. Presets fill typical outputs, from T5 fluorescent 4-tube at 400 to 400W LED at 1900.

Inverse-square assumes a point source. A wide quantum board or a 4-tube T5 behaves like an area source close up, where the real fall-off is gentler, so short distances read lower here than a meter would show. Nothing models tent walls reflecting light back, footprint edges, or photoperiod, so this is centre-of-canopy PPFD and not DLI. The lux column always uses 54 lux per PPFD, a white-LED factor, even after you load the 600W HPS preset where roughly 82 applies.

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