Grow Light Coverage & PPFD Calculator

Built to empower growers at every level. Size lights for even coverage and healthy growth—quickly and confidently. Prefer help? Talk to a Grow Expert.

Grow Light Coverage & PPFD Estimator

Start in Simple. Switch to Advanced for custom fixtures.

Tip: Many LEDs target 600–900 µmol/m²/s for flowering. Check your crop stage.



Per-Fixture Effective Footprint
Total Covered Area
Coverage vs Room
— %
Avg PPFD (covered)
Avg PPFD (room)
DLI
Recommended Fixtures
Why this many?
How to use this calculator (step-by-step)
  1. Measure the plant canopy (length × width in feet).
  2. Choose a preset or switch to Advanced for exact fixture specs.
  3. Set hang height to balance footprint and intensity.
  4. Use 10–20% overlap for uniform coverage.
  5. Enter hours/day to compute DLI.
  6. Calculate and review coverage %, PPFD, and DLI to plan fixtures.

“PPFD (covered)” = intensity across the effectively lit zone. “PPFD (room)” = total PPF spread across the entire room.

Frequently Asked Questions

What PPFD should I target for flowering?

Many growers aim for ~600–900 µmol/m²/s for flowering, depending on genetics, CO₂, and environmental control.

What’s the difference between PPFD and DLI?

PPFD is instantaneous intensity; DLI is total daily photons (mol/m²/day) based on PPFD × hours/day.

How does hang height affect coverage?

Raising a fixture increases footprint but reduces intensity. Use overlap to balance uniformity and target PPFD.

Do I measure the whole room or just the canopy?

Measure the plant canopy. Sizing to the entire room inflates fixture counts and reduces efficiency.