Calculate the Daily Light Integral your grow light delivers, find out how many hours your plants need, and check target DLI ranges for every crop.
1 What are you growing?
Select your crop to get a colour-coded verdict on whether your DLI is in the right range.
2 Your grow light
Pick your light type, then your wattage bracket. The calculator estimates a typical PPFD at normal growing distance (~25–35 cm). If you know the exact PPFD from your light's spec sheet, enter it directly in the field below — that is always more accurate.
Select wattage
μmol/m²/s
PPFD (photosynthetic photon flux density) is the number that actually matters for plants — not watts, not lumens. Lumens measure brightness for human eyes, which heavily weights green light. Plants primarily use red and blue wavelengths. The estimates above use typical efficiency values for each light category and assume a 25–35 cm canopy distance. Actual PPFD can vary ±30% between fixtures in the same category.
3 Daily photoperiod
How many hours per day is your grow light running? Most indoor crops do well with 14–18 hours. Avoid running lights more than 18 hours — plants need a dark period for cellular repair.
h/day
1 Select your crop
Choose the crop you are growing to pull in its recommended DLI range.
2 Your grow light
Pick your light type and wattage to estimate PPFD, or enter a known value directly.
Select wattage
μmol/m²/s
DLI — Daily Light Integral — is the total amount of photosynthetically active light a plant receives in one day. It combines both light intensity (PPFD) and duration. The ranges below are drawn from controlled environment research by Bugbee at Utah State University and Mitchell et al. at Purdue University, two of the most cited sources in commercial LED horticulture.
Crop
Target DLI
Range
Difficulty
Natural DLI in Estonia by month
On a clear day outdoors in Tallinn, these are approximate DLI values from sunlight alone. Most crops need significantly more than winter sun provides — even herbs struggle at DLI below 6. A grow light must make up the entire difference for indoor plants away from a bright south-facing window.
DLI ranges: Bugbee (Utah State) & Mitchell et al. (Purdue). PPFD estimates: typical photon efficacy values by light category.indoorgarden.ee