Indoor growing tool
Grow Light Calculator
Calculate recommended grow light wattage, target PPFD, fixture count, and DLI for hydroponics, grow tents, and indoor gardens.
Enter the size of your grow space floor area.
Choose square meters or square feet.
Different growth stages need different light intensity.
Enter your current fixture wattage to estimate how many lights you need.
Recommended grow light products
LED grow light
A suitable fixture for this grow setup, with balanced output for canopy coverage and efficient indoor growing.
Length of the grow area.
Width of the grow area.
Choose meters or feet.
Sets target PPFD range.
Typical efficient LED fixtures are often in the 2.3–3.1 µmol/J range.
Used to estimate how many fixtures are needed.
Accounts for real-world losses from fixture spread, height, and room conditions.
Needed for DLI estimation from your target PPFD.
Recommended fixtures for this setup
LED grow light
A suitable fixture for this grow setup, with balanced output for canopy coverage and efficient indoor growing.
Average PPFD at canopy level in µmol/m²/s.
How many hours the lights are on per day.
Used to compare your DLI with typical stage targets.
Products to optimize lighting
LED grow light
A suitable fixture for this grow setup, with balanced output for canopy coverage and efficient indoor growing.
Grow light calculator for hydroponics and indoor growing
This grow light calculator helps indoor growers estimate the right LED grow light wattage, fixture count, target PPFD, and daily light integral for tents, grow rooms, hydroponic systems, and indoor gardens. It is useful for seedlings, vegetative growth, flowering plants, fruiting crops, and general indoor cultivation.
Use the calculator to estimate how much light your grow area needs, compare fixture sizes, and plan more efficient lighting coverage for better canopy development and more consistent plant growth.
How this grow light calculator works
The calculator estimates lighting needs based on grow area and plant stage. In advanced mode, it also uses fixture efficacy and a real-world coverage factor to estimate how much total light output and wattage are needed for your space.
Because real grow rooms are not perfect, the coverage factor adjusts for losses caused by hanging height, spread, layout, and room conditions.
What each parameter means
- Grow area: total canopy floor area that needs light coverage.
- Plant stage: growth phase, which changes target light intensity.
- PPFD: photosynthetic photon flux density at canopy level.
- PPF: total light output of the fixture in µmol/s.
- Fixture efficacy: how efficiently a grow light converts watts into usable photons.
- Coverage factor: practical adjustment for real-world lighting losses.
- DLI: total usable light plants receive per day.
- Light hours per day: photoperiod used to calculate DLI.
Typical target PPFD by growth stage
- Seedling / clone: gentle light levels, typically around 100–300 µmol/m²/s.
- Vegetative stage: moderate light levels, typically around 300–600 µmol/m²/s.
- Flowering / fruiting: stronger light levels, typically around 600–900 µmol/m²/s.
These are practical general-use targets. Final intensity depends on crop type, cultivar, environment, CO₂ level, fixture design, and grower strategy.
How to calculate DLI
The DLI formula is:
DLI helps growers understand the total daily light plants receive, not just momentary light intensity. This is useful when comparing different photoperiods, dimming strategies, and growth stages.
Best practice for indoor growers
- Match light intensity to plant stage.
- Keep fixture height consistent across the canopy.
- Use DLI, not only wattage, when evaluating lighting strategy.
- Check real canopy PPFD with a PAR meter if possible.
- Combine strong lighting with proper climate, nutrients, irrigation, and airflow.
Shipping. 3 day EU delivery
7 to 15 EUR under 30kg. See more on Shipping details page.
60 days returns
You can get a refund or replacement after up to 30 days from purchase.
But we ussualy stand on customers side, so we can give a 60 days time frame!
2 months post sale expert support
It's free.
We are a team of 10 with a decade of wise expirience in growing and gardening, so if you'll have any need of help, we'll guide you to your goal within 2 months from a purchase.
About us. Our 9 year history
GoToGarden started in 2017 out of personal frustration. Our founder was a hobby grower who spent hours navigating online shops that felt built by people who had never touched a plant — cluttered layouts, vague product descriptions, no real guidance on what to actually buy or why. He knew there had to be a better way.
See more on About us page
Check out other calculators!
Estimate nutrients, lighting, VPD, irrigation, plant spacing, grow planning, etc.