25 Soft White LED Light Bulbs Tested for CRI, Flicker, Blue Spike, and Dimming Performance

I bought 25 of the best-selling soft white LED 60-watt equivalent light bulbs on Amazon and if you’re only interested in my conclusion, the Philips Ultra HD 60-watt equivalent is the best lightbulb on the market, and it’s not even close. 

I’ve got a link to that bulb below but stick around if you’re interested to see why it’s the best as I compare all 25 LED bulbs to a 60-watt incandescent bulb, a 60-watt equivalent compact fluorescent bulb and this ultra-high end LED bulb that I paid $22 for.  As always there are no sponsored reviews on this website, I bought all these bulbs with my own money, and all the values that I report are the results of my own testing rather than relying on manufacturer claims.

In the first test we’ll measure their efficiency by comparing their advertised power draw and brightness to their actual values.

After that we’ll look at their color rendering index and light emission spectrum.

Then we’ll see which light bulbs have the least amount of perceptible flicker.

For dimmable bulbs we’ll test the uniformity of their dimming curve.

And last, we’ll take each bulb apart and examine the circuitry to estimate how long each bulb should last before a component failure.

Effciency

The main reason to use LED light bulbs over incandescent bulbs is energy efficiency, or the amount of light that they generate per watt of power.  Based on their packaging and Amazon listings, the bulbs claim to generate between 76 and 100 lumens of light per watt.

Using a power monitor and lux meter combined with my highly sophisticated LED testing enclosure, I found in most cases the bulb’s measured efficiencies were close to their stated efficiency, and most of the bulbs produced between 90 and 100 lumens per watt, with the GE bulbs performing especially well with efficiencies around 115 lumens per watt, which is about 20% more than the average.

However, compared to other types of lighting all the LED bulbs were ultra efficient, performing 1300% better than the incandescent bulb I measured which had an efficiency of 7.2 lumens per watt, and 230% better than the compact fluorescent bulb I tested which output 41.6 lumens per watt.

Color Temperature

I also specifically purchased bulbs that were labeled as soft white, but it appears that terminology isn’t completely standardized since some soft white bulbs were labeled as 2700 Kelvin while others were a slightly cooler white color at 3000 Kelvin.  After testing I found there was a significant variation in color with the Phillips Ultra Definition bulb coming in with the warmest color temperature at 2572 Kelvin, which was the most similar to the soft white incandescent bulb I tested.

The most accurate color temperatures were from the Energetic Non-Dimmable bulb and the Regal bulb which were within 5 Kelvin of their stated 2700K temperature.

Blue Spike

However, not all 2700 K light sources are equal, and one of the main complaints about LED lighting is that they have a large blue spike in their emission spectrum which can negatively affect sleep patterns.  The blue spike is due to the fact that the LEDs themselves actually give off blue light, and then use a phosphor coating to create the rest of the spectrum. 

For reference, here’s the emission spectrum of an incandescent light bulb where you can see how much energy is wasted emitting light in the invisible infrared spectrum.  Here is the ridiculously spikey and uneven spectrum from a compact fluorescent bulb, and this is the emission spectrum of a typical LED light bulb with a relatively low red output and significant blue spike. 

I tested the emission spectrum of every bulb and found that the Linkind, Sylvania, and DiCuno bulbs had notably low blue spikes, but the lowest blue spike was from the Philips Ultra Definition bulb. These numbers are also closely correlated to color temperature, though the GE Relax bulb was able to generate very close to 2700 K color temperature without a large blue spectrum spike, which is what that bulb is designed to do.

Color Rendering Index

Blue light effecting sleep patterns isn’t the only problem with uneven and spikey color spectrums, because in real life different objects may reflect or absorb only a specific wavelength of red, green or blue, and if that frequency isn’t emitted by your lightbulb, then the color of those objects won’t look right when lit up by those bulbs.  The term for this concept is the bulb’s Color Rendering Index or CRI and it represents how accurately a light will illuminate the full spectrum of colors.

Most of the LED bulbs claimed to have a CRI above 80, while the Philips Ultra Definition bulbs and the super high end WaveForm LED bulb claimed to have a CRI of 95, and some bulbs like the one from GE didn’t make any CRI claims at all.

In this case the $22 WaveForm LED bulb had an impressive CRI of 96.5, which is actually slightly better than the incandescent bulb, but the $3.50 Philips Ultra Definition bulb was only 0.4 behind that at 96.1.

Both the WaveForm and Philips Ultra Definition bulbs specifically struggled with the R9 color, which is a pure red color that tends to be difficult for LEDs to correctly render due to their lower emission in the red spectrum. 

For reference here’s the CRI report for the incandescent bulb, which as you can see does a much better job with reds due to its heavily red shifted emission spectrum.

The DiCuno bulb also performed very well with an average CRI of 91.4 which is impressive for a lower cost bulb, and you can see it struggled in the same R9 test, but also had lower values for R10 and R12 which are in the yellow and blue spectrum, but 91.4 is still an excellent score for a $2 bulb.

Flickering

Another critical argument made against LED bulbs is that they can flicker, which is caused by the fact that our electrical grids use alternating current or AC.  In the US, our grid runs at 120V 60Hz AC which means it actually oscillates between +170 and -170V, passing through zero volts 120 times per second.  Whenever it crosses that zero line it means no voltage is present and no power is delivered to the bulb which means even an incandescent lightbulb turns off 120 times per second.

However, the important aspects for our perception of flicker are the difference in the brightest and dimmest value which is represented by % flicker, and the difference in total light output at the average brightness compared to the light output above the average brightness which is called the flicker index.

An incandescent bulb’s flickering is almost imperceptible since it’s light is the result of the superheated tungsten filament, and when the voltage drops to zero for a split second that filament stays pretty hot, meaning the depth of the flicker is minimal.  Using a specialized flicker meter I measured the incandescent bulb at a 9.5% flicker percentage, but only a 0.03 flicker index which is very low. 

Lots of the bulbs were advertised as “flicker free,” but the $22 WaveForm bulb was the only one to actually live up to that claim.  You can see the difference between the brightest and dimmest point was less than 1% and the flicker percentage was also under 1% leading to a flicker index of 0.00, so low that the flicker meter occasionally stopped detecting any flicker at all. 

The only other bulb that outperformed the incandescent was the Philips Ultra Definition bulb which had a 6 times lower flicker percent at just 1.5%, and also a 3 times lower flicker index of just 0.01, which isn’t as good as the WaveForm, but still extremely impressive and it does all that while still being a dimmable bulb, which the WaveForm is not.

Dimming Curves

Speaking of dimming, modern dimmable LED bulbs work well with modern dimmers, but I’ve heard the complaints that the dimming curve is uneven, that they don’t get dim enough, or what I’ve personally experienced is that at the dimmest level there is a noticeable brightness fluctuation, different than flicker, but definitely noticeable.  To test this, I set up a Shelly dimmer and measured each bulb’s brightness at 5% and 10%, and then 10% increments all the way up to 100% and mapped their dimming curve.  I also visually inspected each bulb at 5 and 10% brightness for any noticeable brightness fluctuation.

The only two bulbs to resist brightness fluctuations at 5% and 10% were the incandescent bulb which had a minimum lux value of 22.6 at 10% but didn’t turn on at 5%, and the Phillips Ultra Definition bulb which turned on at 5% with an extremely low lux value of 4, and at 10% it output 225 lux, again with no brightness fluctuations.

Only the Philips, GE Relax, and Linkind bulbs were able to turn on below 10%, and of those, the Philips was the only one that had a stable dimming curve that didn’t plateau after 70%.

So, recapping all the tests so far, out of the affordable brands the Philips Ultra Definition bulb performed the best in every category except efficiency, where it still surpassed the average and was within 1% of its advertised lumens per watt.   

Bulb Lifespan

But as I was explaining the extreme superiority of the Philips bulb to my wife she said “that’s great, but the one that is the best to me is the one that lasts the longest”, and that’s a hard thing to test since unlike the 1000 hours of life expectancy for an incandescent bulb, LED bulbs are supposed to last 20 to 30 thousand hours, but if we know how these bulbs typically fail we can make a good guess at how long they should last based on their internal components.  Mostly.

I took apart every bulb that I tested and the majority of them look like this with a ring of LEDs, a bridge rectifier, a smoothing capacitor and a current regulating chip. Each LED in the ring is actually 1, 2 or 3  smaller LEDs in a package that then gets covered with that yellow looking phosphor to create white light. 

On these circuits you can generally predict their reliability based on the number of LED chips since more LEDs means that each one has to drop less voltage and will ultimately generate less heat, which is the killer of LEDs.  In this regard I was most impressed by the Great Eagle 800 Lumen bulbs that uses 24 LED packages per bulb but still only cost $1.33 each.

However, things get complicated with the Philips Ultra Definition, GE Classic, and GE Relax bulbs which have the same current regulating circuitry but use filament style LED packages in a glass enclosure instead of having the chips soldered to a circuit board. 

However, knowing that heat is the killer of LEDs I tested the Great Eagle 24 LED bulb vs the Philips Ultra Definition by running each bulb inside the testing enclosure and recording the temperature after an hour.  You can see the Great Eagle 24 LED bulb is about 112 degrees Fahrenheit on the plastic shell but was over 200 degrees at the base which is where it dissipates its heat.  However, after an hour the Philips Ultra Definition glass bulb was just 109 degrees at the top of the bulb and 117 degrees at its hottest point, meaning even after an hour it was fine to handle with my bare hands.  This means that the Philips bulb either overall generates significantly less heat or does a better job dissipating that heat through the glass shell and metal base.  Either way the lower overall temperature of the Philips bulb suggests that the filament style glass bulb will last longer than a traditional aluminum circuit board LED bulb design.

I also ran the same hour-long test with the $22 WaveForm LED bulb and found that although it had the same heating pattern as the Great Eagle, the base never got over 185 degrees before the current regulating chip lowered the power to the LEDS from 9.5 watts down to 8.9 which prevents overheating.

Conclusions

So, as I said at the beginning of the video, the Philips Ultra Definition bulb is by far the best lightbulb I tested, and it’s not even close.  Just to be sure of their quality I also tested an additional package of the soft white 60-watt bulbs which performed equally well, and I ran a set of their 5000K color temperature bulbs through the whole set of tests and they also had extremely low flicker, great CRI and a nice linear dimming curve.  At $3.50 per bulb, the Philips Ultra HD bulbs are getting close to a premium price tag but are well worth it in my opinion.

On the other side of the spectrum the WaveForm lightbulbs did undeniably well, with their zero flicker, great CRI, and 25% more light output than the Philips Bulb, but they did consume 35% more power than the Philips, they aren’t dimmable, and also cost over 600% more per bulb which doesn’t seem worth it for such a small increase in performance.

For something on the cheaper side, the DiCuno bulbs maximize CRI and limit the blue spike for $2.00 each, but had a high amount of flicker.  If you don’t care about CRI and just want low flicker the Partphoner bulbs had a relatively low flicker index for just $1.33 each, and if you’re looking for a cheap bulb that will last a long time and you don’t care very much about the quality of light then the Great Eagle 800 Lumen bulbs put the smallest load on each LED for just $1.33 each.

Links to all the bulbs from this video are below and as always I appreciate if you use those links since as an Amazon affiliate I do earn a small commission on the sale at no cost to you.

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