Light Bulb Database
Find the best light bulbs using criteria you find important. Desktop experience is recommended.
Learn more about the color quality aspects of lighting:
A light’s color temperature is essentially a description of how humans perceive the overall hue of a light source. The color of natural sunlight varies throughout the day, however, it hovers around 5700K for most of the day.
Some lights in our database differ greatly from the manufacturer’s stated CCT, we’ve included our measurements so that you know what you’re buying.
As evening and night roll around, low/no blue light sources with warm color temperatures are ideal, think <2200K.
We’ve included this metric for those looking for effective or ineffective circadian lighting.
CLA is a calculation of the light “postulated to represent the spectral sensitivity of the retinal mechanisms that generate neural signals reaching the human suprachiasmatic nuclei (SCN).”
Phew.
In other words, the higher the CLA the more a light source is going to wake you up and suppress your melatonin.
This metric is relative and arbitrary and can only be used to compare lights in this database against one another.
Your individual sensitivity and distance to light sources will determine their effect on you.
If you’d like to learn more about how this works, you can read about it here on the CS 2.0 Calculator Documentation page.
CRI (Color Rendering Index)
CRI is a unit used to represent the ability of a light source to reflect the true colors of objects, compared to a natural light source, like the Sun.
It’s currently the most popular way of determining the color quality of an artificial light source and can be seen on many light bulb packages.
For CRI, a score of over 90 is considered good, however, I prefer to see over 95 for this metric.
A little dirt on CRI: CRI used to comprise only 8 colors. The average of these would be called the “Ra” or the average R-value. The CRI standard has since added 6 more colors, however, one of them, R9 (deep red) is more difficult to get high scores on. So most companies still only use the first 8 to calculate their “CRI score”.
We use an average of all 15 colors in our calculations, so the CRI score may be lower or higher than what is typically advertised for each light.
TM-30 (Rf and Rg)
TM-30 was created in 2015 and is a new alternative to the CRI standard.
While CRI only measures 8 to 15 colors for its average score, TM-30 uses 99 total colors.
The TM-30 gives us three important metrics:
- Rf or Fidelity: This is a number of 1 – 100 that measures the reflected light accuracy compared to a standard, similar to CRI.
- Rg or Gamut: This number shows how saturated a light source is on average. A number higher than 100 indicates it’s slightly over-saturated, while a number under 100 indicates under-saturation.
- Color Vector Graphic: Finally we get the CVG, which gives us a visual representation of color saturation.
If you’re at all concerned about how similar your light is to sunlight, the only current metric to measure this is the ASD unit developed by Bridgelux.
ASD measures how much a light source varies from a blackbody radiation curve of the same color temperature.
As you can see above, even though all the light sources are 3000K, the ASD percentage is higher for lights that are less similar to the black body curve.
The ASD metric should only be used to compare lights of the same color temperature.
If you’d like to read more, Bridgluxe’s ASD whitepaper is quite an informative read.
Almost all lights have an “invisible flicker”, if this bothers you, our database has lots of info to help you choose flicker-free lighting.
The flicker depth shows how much the brightness of a light source varies from its minimum brightness to its maximum brightness.
For example, a light source that varies from 100 lux to 80 lux, would have a flicker depth of 20%.
Generally speaking, we want this to be as low as possible, as sunlight doesn’t flicker at all.
The waveform graph actually shows you the flicker depth plotted on a 24 ms time slot.
Waveforms can vary dramatically from one light to the next.
It’s possible to associate headaches with certain types of waveforms, so if this is you, you can use this graph to decide which lights might irritate you and which might not.
This graph is based on the IEEE’s PAR1789 flicker standard.
While this standard isn’t perfect, it’s the best we’ve got right now.
This graph essentially takes the flicker frequency, seen in the waveform graph, and plots it against the flicker depth.
The idea here is that the lower the frequency and the higher the depth, the more likely a light source is to cause noticeable biological problems.
The Flicker index is a measurement that takes into account the areas above and under the light’s average output and calculates this as a number.
This gives us a good numerical value for how much time the light source spends away from the median brightness level.
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