What’s this page for?

This page is attempting to keep a record of all the light bulbs around the house. It will also keep an explanation of what things to look for in a light bulb. This way we don’t need to wonder whether or not a light bulb will be compatible with some socket, we will just know. Furthermore, it will make shopping for bulbs easier.

How are light bulbs measured

Bulb Shape

This is a measure of what the shape of the top glass part of the light looks like. There are different series – for example A, B, and BR to name a few – and within each series there are different sizes denoted by number. So within BR there’s BR25, BR30, BR38, and BR40. For more on this I collected some links to a chart in the appendix.

Base Size

This is a measure of the size of the base (the screw part on the bottom). There are a handful of standard sizes and each size has a name and a code. So for example there is a size called “medium” that’s code is E26. I included a chart and some links in the appendix.

Brightness and Watts

Lumens is a measure of brightness. The higher the number of lumens, the brighter the bulb. Back in the day instead of measuring brightness directly they decided to use the number of Watts (the amount of power/electricity the light used) as a rough approximation to how bright it would be. Unfortunately, older bulbs and incandescents might only report their wattage instead of including their lumens. Luckily there are good relation between the Watts an incandescent bulb uses and the bulbs brightness regardless of shape or size. I have a chart of the relation and some links in the appendix.

Color

The color of a light (when it’s a standard color and not like green or blue or whatever) is measured in Kelvin. I explain why in the appendix (equation and everything) but just know that the higher the number the whiter/bluer the light and the lower the number the more orangey/red it is. Unfortunately, instead of companies slapping the 2700K on their lights they give it fancy names like “Soft White” and “Ocean Sunrise” (joke) so I dropped a little chart and an explanation of why we use Kelvin some links in the appendix.

Color Rendering Index (CRI)

This is measure of how the light affects the colors it shines on. So a bulb with a low CRI will distort the colors of everything in the room more than a bulb with a high CRI. CRI’s are measured from 0 to 100 and are based off incandescent lights so incandescent get a 100. Above 80 is considered good and above 90 is considered excellent. I have a fuller explanation in the appendix.

Replacing Bulbs

Tl;dr: Use LEDs, make sure the base fits, match specs if you only replace one.

Some things to keep in mind.

  • Make sure the shape fits. If you’re trying to put a bigoll BR30 into a slot meant for a CA6 you’re prolly going to have problems even if the bases do match.

  • But also don’t worry about it too much. I’d err on the side of making everything that can fit an A19 use an A19 just because it’s the most common shape. Then you can just have a stash of A19 LEDs and they’ll fit everything.

  • Match the color and brightness. If you’re replacing one light in a set of multiple matching lights then make sure the color and lumens are close to the lights your replacing. Or replace all the lights at once.

  • Don’t worry about different types. Don’t worry that you’re slipping an LED next to some incandescent or halogens. As long as the color and lumens match up it’ll look the same. But also don’t buy anything but LEDs.

  • Use LEDs. They’re better in basically every way. CFLs are pretty good but they are less efficient and have mercury in them. So use LEDs because they are better in every way.

House Lights

Location Shape Base Lumens Color Type
Living Room BR30 E26 485 2700K Incandescent
Pia’s Room - lights over bed A19 E26 600 2700K LED
Pia’s Room - four lamps in main room T3 coil* E26 900 2700K CFL
Pia’s Room - working nook lamp A19 E26 800 2700K LED
Pia’s Room - working nook ceiling PAR20 E26 570 2800K Halogen
Pia’s Bathroom - over mirror T4* G9* 480* 2800K* Halogen*
Pia’s Room - plant nook ceiling A19 E26 450* 2700K* Incandescent
Laundry room T3 coil* E26 1170 2700k* CFL
Pia hallway CA7 E26 450* 2700K* Incandescent
Che’s Room PAR30L E26 920 2900K Halogen
Front Room Fan - Bulb 1 T3 coil* E26 1170 2700K* CFL
Front Room Fan - Bulb 2 T3 coil* E26 1600 2700K* CFL
Front Room Fan - Bulb 3 A19 E26 450* 2700K* Incandescent
Front Room Fan - Bulb 4 A19 E26 800 2700K LED
Alma’s Room - floodlights BR30 E26 600 2700K* Incandescent
Middle Bathroom B/CA* E12 ?? ?? Incandescent

*Educated guess

By the way our house looks really dim because most of our lights are like 450 lumens and we don’t have many. We need like 1.5x to 2x the number of lights and they should all be like two or three times as bright.

Scans of Boxes

Living Room

Living Room

Appendix

References

Bulb Shape

Here is an explanation of bulb shapes: Home Lighting 101: A Guide to Understanding Light Bulb Shapes, Sizes, and Codes

Bulb Base

This website has actual pictures of what the bases look like.

This website used to be an explanation of the differences between sizes but idk what happened

Lumens to Watts Chart

Here is a link explaining lumens and watts in a different way.

Color/Temperature Visualization

This is a hot topic (HAH ‘hot’ lmao). Color is really important. So here’s an article talking about it. I also have more opinions below.

This is not quite how it looks IRL but you get the point.

Explanations

Why Kelvin?

There’s a phenomenon called black body radiation. The idea is that everything shines with an internal light. The color and brightness of that light is determined by how hot the thing is. This is why steel (or anything) glows red when you heat it. The reason you probably only have this association for metal and not like plastic or wood is because those things burn or decompose before they get to temperatures that put out light in the visible range. You might think that this is why fire generates light and to an extent that is true but the light from fire largely comes from another path.

There is a (pretty straightforward actually) equation that lets you figure out what colors are produced based on the temperature of the material. As it so happens Kelvin is a measure of temperature (Kelvin = Temperature in Celsius - 273). So they described the color as a temperature because there’s an equation that maps one to the other.

“That’s kinda dumb,” I hear you say. “Why not just use the color instead of this sideways temperature crap?” You ask.

Welp, dear reader, you have to read the section on CRI at this point then come back here.

So if you just read the CRI section/watched then you probably have an idea of why using temperature makes sense. We are interested in the color but it’s not just about the one color, it’s about the whole spectrum. When you buy a 2700K light you want it to have a 2700K spectrum not just light at that one point.

CRI

ElectroBoom has a good video on this and you can just watch his explanation. Or you can stay for mine.

So you may know that the color of light has a wavelength (for visibile light this is usually measured in nanometers or nm). And that’s pretty true. Every individual photon, or packet of light, has a wavelength. However, almost every source of light that we have doesn’t just shoot off one wavelength of light. For instance a screen uses red, green, and blue pixels only. There is no yellow, purple, or brown pixels. So when you see yellow on screen you’re looking at a mixture of red and green.

House lights are a bit different but follow the same principle. The comfortable yellowish of a 2700k incandescent bulb is not a single wavelength of light. It’s actually an entire spectrum. There’s a graph below showing you what I mean.

On the X axis we have the wavelength of light and on the Y axis we have the intensity of that light. So at 3000K there is a lot of light at around 1000nm and then it slopes down.

Note this is a graph of blackbody radiation. This is roughly what how the sun gets it’s light and roughly how incandescent get their light. So it’s all kind of the same stuff but at different temperatures.

The important thing to not here is that the visible spectrum is actually only a very small part of what an incandescent bulb puts out. Everything to the right (longer wavelength) of the visible spectrum is infrared and that little tiny bit to the left (shorter wavelength) is UV. This is why incandescents are so inefficient, they just throw out a bunch of infrared (heat) instead of actual usable light. But I digress.

In terms of CRI incandescents are really good because they have a very smooth slope There’s lots of light all over the spectrum. Although it’s a little orangey, that is to say there’s less blue than yellow. A blue piece of paper seen in this light should be dimmer than red piece of paper because there is way less blue light to reflect back into your eyes.

Here’s the spectrum of an fluorescent bulb.

These colors mix in your brain and produce – I think – about 2700K for this spectrum. But the light is really just made up of a few spikes. This is gonna make everything look weird. Things get their color by reflecting light in different parts of the spectrum so if something is reflecting at like 525nm it’s gonna look really dim compared to something that reflects at 550nm. So at the end of the day everything looks all distorted. Not color accurate.

Below is another spectrum. This time for an LED at like 2700K (I think).

As it so happens LEDs don’t actually have a broad spectrum like this so what the light bulb manufactures do is get LEDs that do blue/UV and then coat the inside of the bulb with something that absorbs blue/UV and emits a broad spectrum. As you can see this is gonna be much closer to an incandescent but blue things will be a little too bright.

In the electroboom video he shows a spectrum that looks like this but theres a spike in the red. What happened is the manufacture didn’t get the coating quite right so they added a red LED to even out the color. The result was that the color was 2700k but the CRI suffered.

At the end of the day CRI is really about the smotheness of the spectrum and how closely it mimics an incandescent/sun/black body radiation spectrum.

Light color opinions

I don’t have a ton of experience but I think my ideal setup would be someting like this:

  • Two switches, one for daytime, one for chill time.
  • Daytime is like 4000K or 5000K with like 1000+ lumen 90+ CRI bulbs and a lot of them. Just really pumping light in. It’s gonna be much closer to outside than you normally get inside.
  • Not daytime is 2700K 750 lumen 90+ CRI dimmable bulbs. This is much less intense light for when the day is winding down and you’re getting ready for bed.