Plant Lighting Calculator

Learn how long and how strong to keep your grow lights on to maximize yield with minimum electricity cost.

Your Application

Cannabis

Step 1

Plant Growth Stage

Select what comes closest based on a regular 15 week schedule

Autoflower

Step 2

Lighting Duration

Specify the lighting duration within a 24 hour period

Step 3

Lighting Intensity

Use your PAR meter to measure PPFD at your plant’s canopy

Result

Vegetative

Hours

420

PPFD

µmol/m²/s

Daily Light Integral

A daily light integral (DLI) of 30 - 45 is optimal for most cannabis plants.

Lighting Duration

The optimal lighting duration for cannabis is dependent on the growth phase and can range from 12 hours up to 24 hours.

Lighting Intensity

PAR levels of up to 1100 umol are optimal for cannabis plants.

Houseplants

How it Works

Input your values to calculate your individual plant lighting recommendation.

The calculation is based on the daily light integral (DLI), which is the main measure for an optimal amount of light for plants.

Plant Species / Genus

Measured PPFD

µmol/m²/s

Lighting Duration

hours

Fruits & Vegetables

How it Works

Plant Family

DLI Requirement

mol/m²/d

Measured PPFD

µmol/m²/s

Lighting Duration

hours

Back to Start

The Science Behind

Calculation Basis

Our calculation is primarily based on the optimal daily light integral (DLI) for each stage of the cannabis plant.

Recommended cannabis DLI for the full growth cycle. Image from our blog article.

The DLI acts as the main measure of the actual amount of light the plant receives and is a product of light intensity (PPFD) and light duration (photoperiod).

CO₂ Supplementation

Our cannabis DLI calculator assumes that you're not supplying additional CO₂ to your cannabis grow. If you do so, we recommend to increase your PPFD by 25%.

PAR and PPFD

Photosynthetically active radiation (PAR) measures light which is used by plants for photosynthesis. It is commonly measured as PPFD in µmol/m²/s and the most relevant measurement for grow lights.

Don’t Have a PAR Meter?

No problem! We recommend our free Photone Grow Light Meter app that is both very accurate and easy-to-use to measure your light's PPFD intensity with your smartphone or tablet.

Download

Additional Resources

Optimally lighting your cannabis plant is dependent on a lot of factors and our calculator can only provide an approximate assumption. If you want to learn more about lighting for cannabis, we recommend the article about it on our blog.

Blog Article