• Skip to main content
  • Skip to secondary menu
  • Skip to primary sidebar
  • Skip to footer

Grow Light Info

Helping You Choose the Right Grow Light

  • Grow Light Reviews
    • Blurple LEDs
      • Advanced Platinum Series Review
      • BestVA DC Series Review
      • Higrow LED Review
      • King Plus 1000 Review
      • Viparspectra PAR Series Review
      • Viparspectra Reflector 600 Review
    • COB LEDs
      • Aglex COB LED Review
      • CREE CXB3590 COB Review
      • Phlizon COB Series Review
    • Quantum LEDs
      • HLG Quantum Board Review
      • Kingbrite Review
      • Mars TS & SP Series Review
      • Maxsisun PB Series Review
      • Meijiu Review
      • Spider Farmer SF Review
    • Fluorescent Lights
      • Hydrofarm AgroBrite T5 Review
  • Buying Guides
    • HID Guides
      • Best CHM Grow Lights
      • Best HID Grow Light Kits
      • Best HPS Brands
      • Best MH and HPS Bulbs
    • LED Guides
      • Best LED Grow Lights
      • Best COB LED Grow Lights
      • Best Full Spectrum LEDs
      • Best 2000w LED Lights
      • Best Dimmable LEDs
      • Best T5 LED Lights
      • Best LEDs For Flowering
      • Best 300w LED Lights
      • Best LEDs Under $100
      • Best UFO LEDs
      • Best Blue LEDs
      • Best LED Grow Light Strips
    • Other Guides
      • Best Large Grow Tents
      • Best Small Grow Tents
      • Best Fan For Grow Tents
      • Best Grow Light Stands
      • Best Small Grow Lights
      • Best T5 Bulbs For Veg
      • Best Trichome Microscope
      • Best Digital Weed Scale
      • Best Weed Trimming Scissors
      • Best Grow Light Timer
  • Grow Light Advice
  • Cannabis Cultivation
    • Best Place To Buy Marijuana Seeds
    • Best Way To Grow Weed Indoors
    • What Do I Need To Grow Weed?
    • Growing Tips & Advice
You are here: Home / Grow Light Advice

PAR Vs Lumens (Differences And Which Is Better)

Last updated October 8, 2020 By Steven Leave a Comment

PAR Vs LumensMy light’s got tons of lumen, yo!

So what? mine has way more PAR!

Lumen or PAR? Which is better? And does it even matter?

More to the point, what do those terms actually mean?

We’ll cover that and more. Because it does matter.

Indoor agriculture has been booming, with investment in indoor agri-technology solutions estimated at $52 million in the US alone, for the period from 2011 to 2014 [1].

The use of grow lights is a vital component of indoor agriculture, either to supplement natural light, to lengthen daylight, or as a substitute for natural lighting where it is not adequately available.

So if you’re planning on growing indoors, chances are, you’ll need a grow light.

And that means you’ll need a way to determine how “good” it is.

You need to know how to compare the ratings given for different grow lights and how to decide which one is best for your intended application.

The most important factor to consider is the output of the light. Unfortunately, this can be a huge source of confusion, since several terms, most notably lumen versus PAR, are used in determining light output from grow lights.

Contents

  • 1 What Is A Lumen?
  • 2 What Does PAR Mean In Lighting?
      • 2.0.1 PPF Weighted PAR
      • 2.0.2 YPF Weighted PAR
  • 3 PAR Vs. Lumens: Which Is Better?

 

What Is A Lumen?

A lumen is defined by the Merriam-Webster dictionary as “a unit of luminous flux equal to the light emitted in a unit solid angle by a uniform point source of one candle intensity” [2].

Generally, lumens are used to measure the brightness of light as perceived by the human eye.

Grow lights are commonly rated in lux, which is simply lumens per square meter.

Since the use of lumen for measuring light intensity focuses on human perception, the range of wavelengths used in determining the intensity of a light source in lumens is usually limited to between 400 and 700 nm, which excludes infrared and ultraviolet light.

what is uv light

Additionally, extra weighting is given to yellow light since research has shown that the human eye has maximum sensitivity to light at a wavelength of 555 nm in daylight conditions [3], which falls right in the middle range between green and yellow light.

The problem is, yellow light is actually least useful to plants. We need a measurement that takes into account what plants want, not what we see best.

That’s where PAR comes in.

 

What Does PAR Mean In Lighting?

PAR, which stands for Photosynthetically Active Radiation, describes the waveband between 400 and 700 nm. This is the light that is used by plants for photosynthesis.

Thus, the focus of PAR is on light wavelengths that the plant interacts with during the process of photosynthesis.

This wave band overlaps with the visible spectrum used in lumen calculation.

Sensors used to measure PAR use one of two different weighting methods in arriving at the final value: the PPF (photosynthetic photon flux) and the YPF (yield photon flux).

 

PPF Weighted PAR

PPF weighting gives equal importance to all photons of light falling between the 400 to 700 nm spectrum. This results in a relatively simple measurement system.

However, while it is useful for comparing the output of different grow lights, this method of weighting does not adequately address the difference in the sensitivity of chlorophyll at different light wavelengths.

That is why YPF weighting has been developed.

 

YPF Weighted PAR

In YPF weighting, the range of the waveband considered is extended to between 360 and 760 nm, allowing it to accommodate infrared and ultraviolet wavelengths.

Additionally, photons in this range are weighted based on the sensitivity of chlorophyll to light in each particular wavelength. This yields a value that accurately represents the usefulness of the emitted light to the growing plant.

However, since the weighting is based on a graph of spectral sensitivity, the implementation of this weighting method in sensor development is more involved than for PPF based systems.

Plants respond particularly well to blue light (between 400 and 460 nm) and red light (between 580 and 700 nm). That means blue and red light are given more weight in YPF weighting.

In particular, blue wavelengths are particularly useful for vegetative growth while red wavelengths are especially needed during flowering and fruit production [4].

 

PAR Vs. Lumens: Which Is Better?

Despite the existence of overlap in the wavelengths used to calculate lumen and PAR, the relatively higher weighting given to yellow light, to which plants are not particularly sensitive, makes lumen values less useful in the selection of grow lights.

The ideal rating would involve the use of YPF weighted PAR, but even the use of PPF weighted PAR, which considers equally all wavelengths within the photosynthetically active waveband, gives a better estimate of a particular grow light’s impact on plant growth than the lumen value.

This is especially true for the majority of LED plant lights, which are heavy in red and blue spectrum light and do not contain as much yellow and green light.

In summary, both lumen and PAR are useful values for determining light intensity.

A higher lumen light will appear brighter to the human eye, because the weighting of the different wavelengths in determining lumen value for a lamp is based on the sensitivity of the human eye. This means that yellow-green wavelengths are given the highest weighting.

Lumen is great for measuring the light intensity when you are lighting your home, or any other space for humans.

But for an indoor grower, PAR is a better indicator of the effect a grow light will have on the growth of the plant, since higher weighting is given to wavelengths necessary for stimulating growth and for the development of leaves, fruit and flowers.

Choosing a light with higher PAR ratings throughout its coverage area means better growth and higher yield in your indoor garden. The lumen rating of the light does not tell you as much about its effectiveness for plants.

Lumens are for humans; PAR is for plants.

Sources

  • [1] “Indoor Crop Production Feeding the Future “, Newbean Capital, Local Roots and Proteus Environmental Technologies, March 2015, https://indoor.ag/white-papers/
  • [2] “https://www.merriam-webster.com/dictionary/lumen“, accessed 31st January, 2017
  • [3] “https://en.wikipedia.org/wiki/Spectral_sensitivity“, accessed 31st January, 2017
  • [4] “http://www.growell.co.uk/blog/2015/03/light-measurement-lumens-lux-par-and-micromoles“, accessed on 31st January, 2017.

Share this:

  • Click to share on Facebook (Opens in new window)
  • Click to share on Pinterest (Opens in new window)
  • Click to share on Twitter (Opens in new window)
  • Click to share on Reddit (Opens in new window)

Reader Interactions

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Primary Sidebar

Cannabis Cultivation

Best Water For Weed Plants

Best Water For Weed Plants (Ideal Temperature, PPM, pH)

Growing Autoflowers Without Nutrients

Growing Autoflowers Without Nutrients (Is It Possible?)

Pruning To Increase Yield

Pruning To Increase Yield (Only If You Do It Right)

Best Humidifier For Grow Tent

Best Humidifier For Grow Tents (Reviews And Comparison)

Grow Tent Vs Grow Room

Grow Tent Vs Grow Room (Differences And Which Is Best For You)

Best Lights For Vegging Cannabis

Best Lights For Vegging Cannabis (Two Types Stand Out)

Quictent 4 by 4 grow tent

Quictent Grow Tent Review (Is The Slightly Higher Price Worth It?)

Carbon Filter Outside Grow Tent

Carbon Filter Outside Grow Tent (What You Need To Know)

Flowering Clones Back To Veg

Can You Switch Flowering Clones Back To Veg? (And How To Do It)

Secret Jardin Grow Tent Review (Great Value At All Price Points)

More Posts from this Category

Buying Guides

Best Timer For Grow Lights

Best Timer For Grow Lights (Reviews And Buying Guide)

Best Scissors For Trimming Weed

Best Scissors For Trimming Weed (Reviews And Buying Guide)

Best Digital Scale For Weed

Best Digital Scale For Weed (Reviews And Buying Guide)

Best Microscope For Checking Trichomes

Best Microscope For Checking Trichomes (Reviews And Buying Guide)

Best Fan For Grow Tents

Best Fan For Grow Tents (Reviews And Comparison)

Recent Reviews

Vivosun Grow Tent Review (Low Price, But How Is Quality?)

Bloom Plus Review (Good Budget Quantum LED Grow Lights?)

Aceple AG-6000 review

Aceple AG-6000 Review (Can It Really Substitute A Spyder Or Gavita?)

ChilLED Growcraft Review (A Viable Spyder Alternative?)

Viparspectra XS Series Review (Budget Price, Name-Brand Components)

Viparspectra Pro Series Review (Budget Quantum LED Grow Lights)

Timber COB LED Review

Timber Grow Lights Review

Rapid LED DIY COB Review

Rapid LED DIY COB Grow Light Kits Review

Meijiu quantum board 480w led grow light

Meijiu Quantum Board LED Grow Light Review

Kingbrite Quantum Board LED Grow Light Review

Kingbrite LED Grow Light Review

Recent Articles

Types Of Grow Lights For Indoor Plants

Types Of Grow Lights For Indoor Plants (Which Is Best For You?)

How To Tell If A High Pressure Sodium Bulb Is Bad

How To Tell If A High Pressure Sodium Bulb Is Bad

6/2 Light Schedule

6/2 Light Schedule (Why We Don’t Recommend It)

Leaving Grow Lights On 24 Hours

Leaving Grow Lights On 24 Hours: Killer Yield Or Yield Killer?

What Size Grow Tent Do I Need For Plants

What Size Grow Tent Do I Need For X Plants?

Footer

Important Pages

  • Home
  • About
  • Contact
  • Privacy Policy
  • Resources

Follow Us

  • Facebook
  • Pinterest
  • Twitter

Search

Image Reuse

Images on this site are free to share (unless attributed to a 3rd party), as long as you give credit to Grow Light Info and provide a link back to the page from which the image came.

Disclaimer

Some recommended products may use affiliate links. GrowLightInfo.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com. As an Amazon Associate I earn from qualifying purchases.

*Amazon and the Amazon logo are trademarks of Amazon.com, Inc, or its affiliates.

Copyright © 2022 · Grow Light Info · All rights reserved.