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Grow calculators – electricity cost, LED and ventilation
Calculate energy use, running cost, approximate LED power and ventilation requirements in one place.
These tools help you compare equipment options and estimate operating costs before buying or changing your setup. Results are approximate: real energy use depends on device power and runtime, while LED and ventilation choices should also be checked against the specifications of the actual equipment.
How to use the calculators
Choose a tool from the grid above. Each calculator works independently, so you can use only the section you need.
1. Enter actual power draw
For energy cost, enter watts, quantity and daily runtime. Add a humidifier, dehumidifier, pump, heater or other devices if they are part of your setup.
2. Enter the grow area dimensions
The LED calculator uses area as a starting point. Confirm the final choice using fixture efficacy in µmol/J, PPFD maps, hanging height and dimming capability.
3. Include airflow resistance
For ventilation, tick carbon filter, long ducting and bends when present. These components reduce real airflow, so the fan should have sufficient reserve capacity.
01
Electricity use and cost calculator
Calculate the energy use of lighting, ventilation and extra devices from their actual power draw and runtime.
Lighting
Extraction fan
Additional devices
Add only the devices you actually use.
Result
Per day—kWh
30 days—kWh
Daily cost—EUR
Monthly cost—EUR
Full cycle cost—EUR
How is energy cost calculated?
For each device the calculator uses: watts ÷ 1000 × quantity × hours of operation. The resulting kWh value is then multiplied by the electricity price you enter.
The monthly figure uses 30 days. Full-cycle cost uses the number of days entered in the form. Your real bill can differ when equipment cycles on and off or uses variable power through thermostats, controllers or dimmers.
02
LED power calculator
Enter the grow area dimensions to get an approximate LED wattage range.
Area—
Approximate range—
Recommended range—
Matching shop categories
The category match is based on the dimensions and estimated wattage range. Before buying, check the specifications of the actual light and the exact tent dimensions.
Cheapest complete kits for this size
We show available kits matched by size, starting with the cheapest. LED kits are prioritised.
This is an estimate. Also check fixture efficiency (µmol/J), PPFD distribution and manufacturer recommendations.
Why wattage alone is not enough
Two fixtures with the same wattage can deliver different amounts of useful light. Fixture efficacy, diode layout, optics, hanging height and PPFD uniformity all matter.
Use the calculator to narrow down the power class, then compare the specifications and PPFD map of the actual fixture before choosing a model.
03
Growbox ventilation calculator
Estimate fan capacity from growbox volume and additional airflow resistance.
Growbox volume—
Base value—
Recommended fan—
The result is approximate. Actual airflow depends on the filter, duct diameter and length, bends and temperature.
How to read the ventilation result
Fan ratings are usually measured without the full resistance of a working installation. Carbon filters, long ducts and bends reduce real airflow, so the calculator adds reserve capacity when you select them.
For complex ducting or quiet low-speed operation, choosing a fan with extra capacity and speed control can make the system easier to tune.
04
Nutrient feeding charts
Choose a brand to open its feeding chart directly in the current language.
How to use feeding charts
A manufacturer feeding chart is a reference, not a requirement to use the maximum dose. Use the chart that matches your substrate or growing system and check the units carefully.
When combining several products, watch plant response and the total nutrient concentration. In mineral feeding, coco and hydro systems, EC and pH monitoring can help you follow the chosen program more accurately.
FAQ
FAQ – grow calculators, energy, LED and ventilation
Common questions about electricity calculations, lighting, ventilation and nutrient feeding charts.
How does the electricity cost calculator work?
It adds the energy use of all devices in kWh and multiplies it by the price per kWh. The calculation uses actual wattage, quantity and daily runtime.
What electricity price should I enter?
Use your current rate from your bill or tariff. When comparing two setups, use the same rate for both calculations.
How much energy does a 100 W LED use?
At 12 hours per day, a 100 W light uses about 36 kWh in 30 days. At 18 hours per day, about 54 kWh.
How much energy does a 300 W LED use?
At 12 hours per day, about 108 kWh in 30 days; at 18 hours per day, about 162 kWh.
How much energy does a 600 W light use?
At 12 hours per day, about 216 kWh in 30 days. At 18 hours per day, about 324 kWh.
Can I add several extra devices?
Yes. Add as many devices as needed and set power, quantity and runtime separately for each one.
What usually uses the most electricity in a growbox?
Lighting is usually the largest load, but heating, air conditioning and dehumidification can also become major consumers when they run for many hours.
Why can my real electricity bill differ from the calculator?
The calculator assumes the runtime and fixed wattage you enter. Thermostats, humidity controllers, dimmers and variable-speed devices can change real consumption.
How is LED wattage estimated for the area?
The calculator converts the area into an approximate power range. It is a starting point, not a replacement for the specifications of the actual fixture.
Does more LED wattage always mean better lighting?
No. Efficacy in µmol/J, PPFD distribution and uniformity are also important. A more efficient fixture can use the same power more effectively.
Does a carbon filter affect required fan capacity?
Yes. A filter creates airflow resistance, as do long ducts and bends, so extra fan capacity is useful.
Can I enter 24 hours per day for a fan?
Yes. Runtime accepts up to 24 hours. Enter the actual operating schedule for the most useful estimate.
How is full-cycle cost calculated?
Daily energy use is multiplied by the number of days and your electricity price. If schedules change during the cycle, calculate each stage separately.
How can I reduce electricity cost?
Match equipment to real needs: efficient LED lighting, suitable wattage, correctly sized ventilation and avoiding unnecessary heating, cooling or dehumidification.
Do I have to use the full dose shown in a feeding chart?
Not always. Feeding charts are reference programs. Adjust dosage to the substrate, water quality, plant condition and other products being used.