Plant Care
- • Climate Control & VPD16
- • Disease & Pest Management14
- • Nutrient Solutions & EC34
- • Plant Health Monitoring7
Inputs
12 parameters · live recalculation on every change
M²
1m²
50m² default
1000m²
µMOL/M²/S
100µmol/m²/s
600µmol/m²/s default
2000µmol/m²/s
H/DAY
1h/day
18h/day default
24h/day
$/KWH
0.05$/kWh
0.15$/kWh default
1$/kWh
Pro Settings — Lab Controls
0.5
0.9 default
1
0.5
0.95 default
1
0.1
1 default
1
Advanced Settings — Deterministic Corrections
W
100W
600W default
2000W
µMOL/J
1µmol/J
2.5µmol/J default
4µmol/J
FX
1fx
10fx default
100fx
%
0%
10% default
30%
Insight band · live
From HPS baseline to LED daily cost
The HPS daily bill, pulled down by the LED bank — the running total lands on the LED daily cost.
- HPS baseline $62.4 $62.4
- − LED savings $19.6 $42.8
- LED daily cost $42.8 $42.8
Energy / day: 285.1 kWh
Savings: 45.8 %
Running total after each term — the final net matches the headline reading in the result card, kept in sync live.
Deterministic model
12 inputs · 10 outputs
Runs 100% in your browser
This is a deterministic model: the same inputs always produce the same outputs, calculated entirely in your browser with nothing sent to any server. It is a planning aid — not a quote, not a dosing instruction, and not a yield forecast. Treat every line as a working estimate and validate it against your own prices and measurements.
It models one system: Size the grow light bank off the canopy target and price the electricity it pulls. Enter the grow area and the PPFD target — the engine converts that to the fixtures you actually need by dividing required photon flux by fixture wattage × efficiency along with the maintenance, thermal and dimming derates, then turns fixture count into kWh/day at your photoperiod and ballast loss and into cost per day at your rate. Cost per month, cost per 90-day cycle, delivered PAR and a green—yellow—red efficiency band follow, with the LED-vs-HPS arm computing the daily savings of running a 2.5 µmol/J LED bank against a 1.7 µmol/J HPS alternative.
What the Lighting Cost Calculator — LED vs HPS & Electricity Blueprint returns
The engine computes 10 outputs from your 12 inputs. The headline number is Cost / Day ($/day), alongside Cost / Month, Cost / 90-Day Cycle, Energy / Day. 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
Compute the required photon flux: PPFD × grow area — both in the units the canopy actually receives and the area it covers.
STEP 02
Split that flux across one de-rated fixture: N = PPFD × A ÷ (efficiency × wattage × maintenance × thermal × dimming), rounded up to whole fixtures.
STEP 03
Charge the photoperiod: kWh/day = N × watts × hours ÷ 1000 × (1 + ballast/100) — the ballast overhead sits on top, invisible at the bulb.
STEP 04
Price it: cost per day = kWh × rate, then cost per month (×30) and cost per 90-day cycle fold the recurring line into the production budget.
STEP 05
Verify the optics: delivered PAR = N × w × e × m × τ × δ ÷ A against the target, plus the effective µmol/J after the three derates.
STEP 06
Run the comparison and the band: LED cost at your efficiency vs HPS at 1.7 µmol/J, then green/yellow/red on e_eff with the $50/day bill red flag.
N = \frac{PPFD \cdot A}{e \cdot w \cdot m \cdot \tau \cdot \delta}
Fixtures needed — required photon flux over one de-rated fixture
E = N \cdot w \cdot \frac{H}{1000} \cdot \left(1 + \frac{B}{100}\right)
Energy per day — fixtures × watts × photoperiod, ballast overhead
C = E \cdot r
Cost per day — energy × electricity rate
C_{30} = 30 \cdot C, \qquad C_{90} = 90 \cdot C
Cost per month and per 90-day cycle
PAR = \frac{N \cdot w \cdot e \cdot m \cdot \tau \cdot \delta}{A}
Delivered PAR — the full bank spread over the canopy
e_{eff} = e \cdot m \cdot \tau \cdot \delta
System efficiency after maintenance, thermal and dimming
S = C_{HPS} - C_{LED}, \qquad e_{HPS} = 1.7
LED vs HPS savings — your bank at e, alternative at 1.7 µmol/J
\text{green } e_{eff} > 2.0,\ \text{yellow } 1.5{}^{\circ}2.0,\ \text{red } < 1.5 \, \text{or} \, C > 50
Efficiency band and the $50/day bill flag
Fixture count is the archived grow-light watts-needed equation resolved into whole units: the old engine computed required watts = target DLI ÷ (photoperiod × 0.0036) × area ÷ efficacy — this arm works off PPFD directly and rounds up.
Efficiency figures come from the archived efficacy table — LED 2.0–2.7, CMH 1.5, HPS 1.3 µmol/J — and the light-type select feeds those typicals into the efficiency field when you switch.
The ballast line is the running-cost overhead: an HPS magnetic ballast banking 10–25% loss is exactly what LED drivers largely eliminated, which is why kwh × (1 + ballast/100) belongs in every LED-vs-HPS bill.
Delivery is never the rating: PAR actual divides the de-rated bank over the real footprint, matching the archived coverage-factor discipline where PPFD = PPF × coverage ÷ area.
The HPS benchmark sits at 1.7 µmol/J — a modern double-ended HPS rather than the archived 1.3 legacy figure — so the savings arm is honest against equipment the room can actually buy today.
The cost red flag at $50/day mirrors the running-cost honesty: efficiency alone never tells the whole story, and a bill over $50/day trips the band regardless of how fancy the µmol/J is.
- Fixture count: N = PPFD × area ÷ (efficiency × wattage × maintenance × thermal × dimming) — the archived grow-light engine back-computed watts needed from a DLI target as target ÷ (photoperiod × 0.0036) × area ÷ efficacy; this arm resolves the same equation into whole fixtures.
- PPF and PAR delivered: PPF = watts × efficiency; PAR = N × watt × efficiency × maintenance × thermal × dimming ÷ area — the archived engine computed PPF = watts × efficacy then spread it over the footprint with a coverage factor.
- Energy per day: kWh = N × watt × hours ÷ 1000 × (1 + ballast/100) — the archived running-cost and energy-simulator engines carried daily kWh = kW × hours × (1 + overhead) into monthly dollars.
- Cost per day / month / cycle: cost = kWh × rate × (1, 30, 90) — the archived hydroponic-cost and running-cost calculators converted Watts × hours ÷ 1000 × rate into daily and monthly dollars; the 90-day cycle read is built into the blueprint.
- LED vs HPS: LED cost at fixture efficiency, HPS at 1.7 µmol/J — the archived efficacy table (LED 2.0–2.7, CMH 1.5, HPS 1.3 µmol/J) plus the modernized 1.7 HPS figure bracket the savings arm at the same PPFD, area and photoperiod.
- Efficiency band: green above 2.0, yellow 1.5–2.0, red below 1.5 µmol/J or over $50/day — the archived LED-vs-HPS scoring style applied to the system µmol/J, with the daily-bill red flag carried from the running-cost honesty.
This model combines the earlier Lighting-cost-calculator, Led-vs-hps-cost, Grow-light-electricity-calculator models.
Q1: How to calculate grow light electricity cost? ▾
Grow light electricity cost = kWh/day × rate, where kWh/day = fixtures × watts × hours ÷ 1000 × (1 + ballast/100). First size the bank: fixtures = PPFD × area ÷ (efficiency × wattage × maintenance × thermal × dimming). For a 50 m² room at 600 PPFD with 600 W, 2.5 µmol/J LED fixtures that resolves to 24 fixtures at ~285 kWh/day — at $0.15/kWh that is a $42.77 daily bill, $1,283 a month and $3,849 over a 90-day cycle. The tool walks every line so the rounded-up fixtures, the ballast overhead and the de-rates are all visible.
Q2: LED vs HPS cost comparison: which is cheaper? ▾
Holding PPFD, area and photoperiod equal, cost splits only on µmol/J: fixtures = PPFD × area ÷ (efficiency × wattage × derates). An HPS at 1.7 µmol/J needs 2.5 ÷ 1.7 ≈ 1.47× the fixtures of a 2.5 µmol/J LED, so at identical wattage and run time the HPS bill lands about 47% higher. On the 50 m² / 600 PPFD default that is roughly $62/day HPS against $43/day LED — a $19.60/day saving the comparison arm computes on the actual inputs. The gap is wider against legacy 1.3 µmol/J HPS and thinner against modern 2.7 µmol/J LEDs.
Q3: How much does it cost to run grow lights per day? ▾
On the tool defaults (50 m², 600 PPFD, 18 h, $0.15/kWh, 2.5 µmol/J, 600 W fixtures) the bank draws 24 fixtures × 600 W = 14.4 kW, burning 285 kWh/day after ballast loss and costing $42.77/day — $1,283/month and $3,849 per 90-day cycle. Cost scales linearly with rate, photoperiod and wattage, so at $0.08/kWh the same room runs $22.81/day while at $0.40/kWh it hits $114. Regardless of the number, any daily bill over $50 trips the red flag because efficiency alone never excuses a runaway power line.
Q4: What is a grow light cost per day calculator for? ▾
It converts a PPFD target into the fixture bank and then into the recurring electricity line, so the decision is power, not parts: fixtures needed = PPFD × area ÷ (efficiency × wattage × maintenance × thermal × dimming) and cost = fixtures × watts × hours ÷ 1000 × (1 + ballast/100) × rate. The same PPFD on a 2.0 µmol/J budget LED versus a 2.7 µmol/J high-end LED means more fixtures and more kWh for the identical canopy — the calculator makes that gap visible as dollars per day and across the 90-day cycle.
Q5: How many grow light fixtures do I need for my room? ▾
N = PPFD × area ÷ (efficiency × wattage × maintenance × thermal × dimming). A 50 m² room at 600 PPFD with 600 W fixtures needs 600 × 50 ÷ (2.5 × 600) = 20 fixtures before de-rates; after 0.9 PAR maintenance, 0.95 thermal and full power that becomes 24 fixtures, and a dimmed-to-80% room needs more because holding the same PPFD with a dimmer bank takes more units. Feed in your installed count and the panel reports the shortfall or surplus so an under-spec room shows as "needs N more" instead of a mystery PAR loss.
Q6: How many watts or PPFD do I actually need, and what is µmol/J? ▾
µmol/J is photon efficiency: µmol of PAR per joule of input. LED runs 2.0–2.7, CMH 1.5, HPS 1.3–1.7 µmol/J depending on vintage, and it is the single build decision that sets fixtures, kWh and cost. PPFD targets follow the crop: leafy greens run ~400–600 µmol/m²/s, fruiting crops 800–1200 over longer photoperiods, and the archived DLI anchors (leafy 15–20, fruiting 25–40 mol/m²/day) are the cross-check — target the DLI the crop saturates at, not the brightest number on the fixture box.