Plant Care
- • Climate Control & VPD16
- • Disease & Pest Management14
- • Nutrient Solutions & EC34
- • Plant Health Monitoring7
Inputs
8 parameters · live recalculation on every change
µMOL/M²/S
50µmol/m²/s
600µmol/m²/s default
2000µmol/m²/s
HRS/DAY
1hrs/day
18hrs/day default
24hrs/day
MOL/M²/DAY
5mol/m²/day
30mol/m²/day default
60mol/m²/day
Advanced Settings — Deterministic Corrections
W
10W
480W default
2000W
CM
10cm
30cm default
120cm
M²
0.1m²
1.2m² default
20m²
Deterministic model
8 inputs · 8 outputs
Runs 100% in your browser
This is a deterministic model: the same inputs always produce the same outputs, calculated entirely in your browser with nothing sent to any server. It is a planning aid — not a quote, not a dosing instruction, and not a yield forecast. Treat every line as a working estimate and validate it against your own prices and measurements.
It models one system: The photobiology blueprint for the grow room. Convert PPFD and photoperiod into Daily Light Integral, back-calculate the exact PPFD a target DLI demands, and see what raising or lowering the fixture does through the inverse-square law — with delivered efficacy, coverage footprint and the daily running cost in one panel.
What the PAR / DLI Photobiology Lab returns
The engine computes 8 outputs from your 8 inputs. The headline number is Delivered DLI (mol/m²/day), alongside PPFD from Target DLI, Hours Needed, Delivered Efficacy. Every output updates live as you change a parameter.
What it does not do
Outputs depend on the inputs and assumptions shown here. Confirm relevant measurements and local conditions before acting.
STEP 01
Measure the average canopy PPFD (µmol/m²/s) with a quantum sensor, or use the fixture PPF and footprint efficiency.
STEP 02
Set the photoperiod in hours per day — photoperiodic fruiting crops need their dark cycle for respiration.
STEP 03
Compute DLI as PPFD × 3600 × hours ÷ 1 000 000 to get the daily photon volume in mol/m²/day.
STEP 04
Compare delivered DLI to the crop saturation band: microgreens 10–15, leafy/herbs 15–25, strawberry 20–30, tomato/cucumber 25–40.
STEP 05
If under target, extend hours or add wattage — the tool back-calculates both from the target DLI.
STEP 06
If the light sits high, apply the inverse-square law to predict the real canopy PPFD before touching a dimmer.
\text{DLI} = \frac{\text{PPFD} \times 3600 \times \text{Hours}}{10^6}
Daily Light Integral — cumulative photons over the photoperiod
\text{PPFD} = \frac{\text{DLI} \times 10^6}{3600 \times \text{Hours}}
Back-calculated PPFD a target DLI demands at your run time
\text{PPFD}_2 = \text{PPFD}_1 \times \left( \tfrac{d_1}{d_2} \right)^2
Inverse square — photons spread over area as the fixture rises
\eta = \frac{\text{PPFD} \times A_{canopy}}{W}
Delivered efficacy — photons actually reaching the footprint per joule
A_{cap} = \frac{W \times \eta_{type}}{\text{PPFD}_{rated}}
Coverage — the canopy area a fixture can hold at the rated PPFD
\text{\$\/day} = \frac{W \times \text{Hours} \times p_{kWh}}{1000}
Running cost at the planning kWh price
PPFD measures the instantaneous photon flux; DLI is the daily integration. Two different intensities and run times can deliver the same DLI with very different spectral load.
Efficacy values are typical published figures for each technology — LED 2.0–2.7, CMH 1.5, HPS 1.3 µmol/J — and the coverage factor models edge loss at 0.95/0.90/0.80.
DLI assumes uniform PPFD across the stated footprint. Real fixtures fall off toward the edges; the delivered-efficacy number exposes that falloff.
Photoperiodic fruiting crops need a dark cycle for flowering hormones — push PPFD, not hours, in veg-to-flower transitions.
- Internal CEA research — DLI saturation: lettuce 15–20, herbs 15–25, strawberry 20–30, tomato/cucumber 25–40 mol/m²/day.
- Fixture efficacy: LED 2.0–2.7, CMH 1.5, HPS 1.3, T5 0.8 µmol/J. Coverage loss factors 0.95/0.90/0.80 (even/standard/wide).
- Inverse-square law for point-source radiometry — grows-graded and sensor-verified in the V4 grow-light registry.
This model combines the earlier Grow-light-ppfd-dli-calculator, Dli-calculation-blueprint-leafy-greens-fruits, Green-light-penetration-canopy-photobiology models.
Q1: What is DLI and why is it better than PPFD? ▾
PPFD is an instantaneous snapshot — the photon flux hitting the canopy at one moment. DLI (Daily Light Integral) is that flux integrated over all illuminated hours, so it captures total daily light dose. Two setups with very different PPFD and run times can deliver the same DLI, which is why DLI is the number to match against crop saturation targets.
Q2: How many mol/m²/day does each crop need? ▾
Microgreens and seedlings run 10–15, leafy greens like lettuce and kale 15–20, culinary herbs 15–25, strawberries 20–30, and fruiting crops like tomatoes, cucumbers and cannabis 25–40 mol/m²/day. These are grower-proven saturation bands, not research ceilings — pushing past them adds heat load faster than it adds yield.
Q3: What happens when I raise the light? ▾
Raising the fixture spreads the same photons over a larger area, so canopy PPFD drops with the square of the distance — raise from 30 cm to 60 cm and PPFD falls to a quarter. The inverse-square reading is your honest guide before you ever touch a dimmer, which is why mount height is one of the first things to check when DLI comes up short.
Q4: What does delivered efficacy tell me? ▾
Delivered efficacy (µmol/J) is photons that actually reach your footprint per second per watt of input. Compare it to the fixture-type benchmark — 2.4 for typical LED, 1.5 CMH, 1.3 HPS — and the gap exposes reflective loss, dirty lenses or over-widened coverage. If you deliver 1.9 from an LED rated 2.4, the photons are going somewhere else.