Plant Care
- • Climate Control & VPD16
- • Disease & Pest Management14
- • Nutrient Solutions & EC34
- • Plant Health Monitoring7
Inputs
10 parameters · live recalculation on every change
CM
50cm
200cm default
1000cm
CM
30cm
100cm default
500cm
FIXTURES
1fixtures
2fixtures default
20fixtures
µMOL/S
200µmol/s
1000µmol/s default
3000µmol/s
CM
10cm
30cm default
150cm
%
0%
100% default
100%
Pro Settings — Lab Controls
%
80%
90% default
98%
Advanced Settings — Deterministic Corrections
%
0%
0% default
20%
H/DAY
12h/day
18h/day default
24h/day
Insight band · live
From grow area to uncovered corners
The planned footprint, pulled down by what the array covers — the running total lands on the still-dark area.
- Grow area 2.0 2.00 m²
- − Covered 2.9 -0.90 m²
- Uncovered -0.9 -0.90 m²
Uniformity: 95 %
DLI: 58.3 mol/m²/d
Running total after each term — the final net matches the headline reading in the result card, kept in sync live.
Deterministic model
10 inputs · 10 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 Pro-level coverage and spectrum blueprint for a grow area. Enter the footprint, fixture form-factor, photon count, mounting height and dim curve and the engine returns the average canopy PPFD scaled by the inverse-square law, the uniformity grade that separates a bar board from a quantum board, the delivered daily light integral with the sunrise ramp compensated, the inter-canopy light that reaches the lower third, the UV-A and UV-B contribution as a share of the run, and the driver waste-heat and DC-drop load your wiring and cooling must carry.
What the Light Coverage Architect — Bar vs QB, Inter-Canopy & UV Blueprint returns
The engine computes 10 outputs from your 10 inputs. The headline number is Avg Canopy PPFD (µmol/m²/s), alongside Uniformity, Coverage Area, Inter-Canopy PPFD. 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 grow footprint in centimetres and convert to square metres (÷10,000), then set the fixture form-factor, count, emission PPF and mount height.
STEP 02
Compute the average canopy PPFD as fixture PPF × count × dim × 0.9 ÷ area, scaled by the inverse-square ratio (30 cm ÷ height)².
STEP 03
Read the uniformity from the fixture form — multi-bar ~95%, quantum board ~85% — and lift the floor by the fixture-count overlap.
STEP 04
Estimate the lower-canopy hand-off with the deliberate inter-canopy fraction (~40% of top) plus any in-canopy tower flux, and the UV share kept inside the UV-A 0–10% / UV-B 0–2% window.
STEP 05
Integrate the daily light integral for your photoperiod, compensating the peak for a sunrise/sunset ramp so the delivered DLI is preserved.
STEP 06
Size the thermal and wiring load: driver waste heat = fixture watts × (1 − eff/100), and cross-check the PPFD by dividing a lux reading by the calibration factor (~650).
\overline{PPFD} = \frac{N \cdot \Phi_{ppf} \cdot D \cdot \eta}{A} \times \left( \frac{30}{h} \right)^2
Average canopy PPFD — fixture photon flux over the footprint, scaled by the inverse-square mount height
U_{bar} \approx 95\% \quad U_{qb} \approx 85\% \qquad U = \min(\, U_{fx} + (N-1) \cdot 1.5,\, 99.5\%)
Uniformity — multi-bar fixtures hold the ~95% floor, a quantum board ~85%, with a fixture-count overlap lift
A_{cover} = \frac{N \cdot \Phi_{ppf} \cdot D \cdot \eta}{PPFD_{target}}
Coverage area — the footprint your fixtures can hold at the working target PPFD
PPFD_{inter} = \overline{PPFD} \cdot 0.40 \; + \; (\text{inter-canopy} \, ? \, 200 : 0)
Inter-canopy PPFD — the lower third receives ~40% of top light; an in-canopy tower adds its own flux
PPFD_{UV} = \overline{PPFD} \cdot \frac{UV\%}{100} \qquad (\text{UV-A } 0\!-\!10\%\,,\; \text{UV-B } 0\!-\!2\%)
UV contribution — UV share of the run as PPFD, held inside the UV-A and UV-B safety window
DLI = \overline{PPFD} \cdot \frac{h_{photo} \cdot 3600}{10^6} \qquad \Phi_{dim} = \Phi \cdot \frac{D}{100} \cdot \frac{2}{\pi}
Daily light integral — average PPFD over the photoperiod; the dimmed fixture arc averages 2/π of its peak under a sine daylight curve
PPFD_{peak} = \frac{PPFD_{flat} \cdot t_{total}}{t_{total} - 0.5 \cdot t_{ramp}} \qquad t_{ramp} = t_{dawn} + t_{dusk}
Dimming compensation — a sunrise/sunset ramp averages ~50% of peak, so the peak must rise to hold the same DLI
Q_{driver} = V_{w} \cdot (1 - \tfrac{\eta_{eff}}{100}) \qquad Q_{BTU} = Q_{driver} \cdot 3.41214 \qquad PPFD = \frac{lux}{655}
Driver heat and calibration — rejected watts from driver efficiency, BTU/h, and the lux÷factor PAR-meter hand-off
Multi-bar LED fixtures hold a roughly 95% uniformity floor across the footprint; a single quantum board concentrates heat and photons into a center hotspot and settles nearer 85% — the difference is exactly the falloff you see at the edges.
The inverse-square law rules coverage: double the mount height and the on-target PPFD quarters. At 30 cm a 1000-µmol/s fixture throws ~900 µmol/m²/s onto a 2 m² canopy, at 60 cm only ~225.
Inter-canopy light is the difference between a top-lit and a volumetrically-lit plant: the lower third sees only about 40% of top-canopy PPFD by Beer-Lambert, and an in-canopy tower is what recovers it.
UV is a finishing tool, not a main source: hold UV-A near 0–10% and UV-B at 0–2% of the photoperiod in flower only, and ramp it up over days — resin, terpenes and pest defense respond, but stress and bleaching do too.
Adding a sunrise/sunset ramp carves about half of peak per ramp, so the controller must raise the peak PPFD to keep the same total DLI — the compensation arm returns exactly that peak and its percent increase.
Uniformity below 80% is a yield tax: hotspots burn the center while edges stretch. Raise the fixture count, lower the mount, or spread the boards before adding raw photon power.
- Coverage: 1 m² = 10,000 cm², and average PPFD = fixture PPF × count × dim × overview-efficiency ÷ area, scaled by the inverse-square ratio (30 cm / mount height)².
- Uniformity: a multi-bar fixture holds roughly 90–95% of peak across the footprint; a single quantum board drops toward ~85% with a center hotspot — extra fixtures raise the floor.
- Canopy: Beer-Lambert attenuation models depth with exp(−k·LAI), k = 0.6; inter-canopy light returns lower leaves to roughly 40% of top-canopy PPFD.
- UV: supplemental UV-A runs 0–10% and UV-B 0–2% of the photoperiod in flower for resin, terpenes and pest defense — never the full cycle.
- Dimming: a sunrise/sunset ramp carves ~50% of peak per ramp, so holding the same DLI needs requiredPeak = flat × totalMin ÷ (totalMin − 0.5 × rampMin).
- Calibration: PPFD = lux ÷ factor (a fixture-specific ≈650 lx·µmol⁻¹·m²·s default), and driver heat = fixture watts × (1 − eff/100).
This model combines the earlier Bar-led-vs-quantum-board, Inter-canopy-lighting-vertical-towers, Supplemental-uv-light-grow-lights, Grow-light-dimming-curves-sunrise-sunset, Quantum-par-meter-vs-app, Led-grow-light-driver-heat-management models.
Q1: What is the difference between bar LED and quantum board coverage? ▾
Bar LED spreads the emitters into long, even strips, so a multi-bar fixture holds a uniformity floor of roughly 95% of peak across the footprint — the photons land flat from corner to corner. A quantum board concentrates its diodes into a compact panel, creating a center hotspot and a falling edge, settling near 85% uniformity. That 10-percent gap is the coverage tax: bars win on even spread to the edges, boards win on cost per photon and simplicity in a small reflective tent.
Q2: How is average canopy PPFD calculated, and why does height matter? ▾
Average PPFD is the fixture photon flux over the carpet: fixture PPF × count × dim × 0.9 ÷ footprint, then scaled by the inverse-square ratio of the reference height to your mount height, (30 ÷ h)². Height matters enormously because light falls off as the square of distance — double the mount and the on-target PPFD quarters. A 1000-µmol/s fixture at 30 cm over 2 m² lands near 900 µmol/m²/s, but at 60 cm roughly 225. That height is the single fastest dial on coverage.
Q3: How much light does inter-canopy lighting add to the lower canopy? ▾
By the Beer-Lambert attenuation model, light decays exponentially through leaf layers with an extinction coefficient near k = 0.6, so the lower third of a dense canopy receives only about 40% of the PPFD at the top. An inter-canopy or tower fixture placed among that canopy adds its own flux directly to the lower leaves — the engine models it as ~40% of top as the baseline hand-off plus the tower boost — which is how vertical and tiered grow systems salvage the bottom buds a top-only light starves.
Q4: What UV levels are safe and worthwhile on a grow light? ▾
Supplemental UV is a flower-phase finisher, not a grow-phase source. Keep UV-A near 0–10% of the photoperiod and UV-B at 0–2%, and ramp the on-time up over days rather than switching it on cold. In that window, UV drives resin, terpenes and pest defense responses; beyond it you invite bleaching, curling and crispy margins. The engine reports the UV share as a PPFD arm so you can see exactly how much of the canopy dose is ultraviolet.
Q5: How do you compensate PPFD when adding sunrise and sunset dimming? ▾
A sunrise/sunset ramp means the fixture spends time below peak, so to keep the same total photons in the day — the same DLI — the peak must rise. Each ramp averages about 50% of peak over its duration, so the compensation is flat PPFD × full photoperiod ÷ (photoperiod − 0.5 × combined ramp time). The engine returns that required peak and its percent increase over your flat target, so the gentle dawn is paid for by a slightly higher midday instead of a lost DLI.
Q6: How do I size the driver heating and cooling load for my lights? ▾
A driver turns the fraction (1 − efficiency) of its input power into rejected heat that your cooling must carry. Multiply fixture watts by (1 − eff/100) for the waste watts, then factor 3.41214 to get BTU/h. A 500 W fixture at 90% efficiency rejects 50 W of heat a day — and that number is lower when the mount is higher and the dim is lower. The same arm gives the lux÷factor PAR-meter calibration so you can verify the PPFD a phone reading implies.