I am in the process of replacing my incandescent bulbs with more efficient alternatives. My home is about 14 years old, I've owned it for a little over three years. It seems most of the bulbs that it "came with" are original, and since I purchased the house almost every tungsten bulb in a built-in fixture ended up burning out. In particular were the R40 ceiling floods, of which I have 16 in total in the interior. I'd ignored many of them, as I rarely turned most of them on, however when three in my kitchen burned out within a weeks period, I up and replaced the whole lot with EcoSmart (made by Lighting Science) R30 CFL's that offer around 800 lumens.

The initial difference was HUGE. The 14 year old bulbs were extremely dim and VERY orange in color. The CFLs, when fully warmed up, are very nice and bright. I chose cooler colors (3500k and 5000k) which light the place much more naturally (at least to my eyes). The caveat with CFL, as I am learning, is they do not perform well in cooler temperatures. I try to use my heater as little as possible in the winter, generally only heating when the interior temperature drops below 60-64 degrees. All of the CFL R30s I purchased have a common problem, which seems to be common across brands as I've tried TCP, Phillips, and others: Very long warmup time, very low lumens during warmup, and an extreme magenta hue during warmup. The bulbs also do not seem to reach full brightness, and the way the reflectors are designed, the shape of the spiral inside the R30 "can" is clearly visible and appears rather dark.

I've decided to switch to LED, despite the cost. In trying out a few from the local store, they seem far superior to CFL. They start instantly, always produce the same color, are fully dimmable (and seem to dim smoothly unlike CFL), and don't seem to be affected by temperature. I've only ever used R or BR type, however all of the ones at the local store in the color temperatures I prefer are PAR type. The BR type LED floods seem to produce similar quality and diffused light to the CFL's, but the only color I can find are 2700K. What exactly is the difference between an R/BR type flood and a PAR type flood? Additionally, what are the differences between PAR30, PAR38, etc? Are PAR type good for indoor use (in the past, I'd only ever seen a few mentions that PAR type were required for outdoor scenarios, indicating they were better sealed against weather)?

  • Could someone add these tags: flood, PAR?
    – jrista
    Commented Dec 3, 2012 at 4:52
  • 1
    I think a "flood" tag would be confused with "flooding"; there's already a "recessed-lighting", would that do instead? Not sure how useful a "par" tag would be: how often would you need to categorize questions based on the shape of the light bulb (which is what the "PAR" means)?
    – Niall C.
    Commented Dec 3, 2012 at 5:23
  • @NiallC: Sure, [recessed-lighting] will do, as that is what the question is about.
    – jrista
    Commented Dec 3, 2012 at 16:30
  • If this is for recessed lighting fixtures you might look at a LED retrofit kit instead of just bulbs.
    – Craig
    Commented Dec 3, 2012 at 20:57
  • @Craig: I've seen the retrofit kits...they look like they may be more diffuse...what is the benefit of using them over just a bulb?
    – jrista
    Commented Dec 3, 2012 at 21:50

7 Answers 7


Due to the lack of adequate answers, I decided to research the differences myself and provide an answer to the benefit of the community.

PAR Type Lamps

From a build quality and light control standpoint, PAR type lamps are generally considered superior. The explicit parabolic nature of the reflector means light is more precisely reflected directly out of the bulb cavity, with less dispersion, than an R or BR type lens. PAR type lamps, thanks to the design of the lens in front of the actual light emitting element (which is usually a given with home lighting...PAR in general can referr to a very wide variety of lighting which may or may not have a front lens, including high powered stage lighting). The lens is often fresnel in nature, are often additionally capable of focusing the more accurately reflected light into a brighter, narrower spot. The fact that they have a more precisely crafted lens means they are capable of being designed to emit beams of varying angular degrees wide (anywhere from 12° to 70°), with high intensity narrow beams or more diffuse wider beams, makes them highly flexible.

PAR type lamps are also frequently designed in such a way that makes them viable for outdoor use. Not all PAR type lamps are properly sealed for use in humid climates or areas where rain or other water could intrude upon the bulb, but many PAR type lamps are. This is a key difference between PAR and R or BR type lamps.

In terms of nomenclature, PAR lamps are usually designated with a number. The number of a PAR lamp, such as PAR38, gives the diameter of the lamp in inches. In the case of a PAR38, the diameter would be 4.75" (4 3/4"), or "thirty eight eighths of an inch." Common PAR lamp sizes for home are PAR20, PAR30, PAR38, with the latter being most common.

R Type Lamps

One of the more common types of flood light lamps for use indoors, the R-type lamp is a more cheaply constructed "reflector" type lamp. They are not particularly efficient in any key respect, their design is roughly defined and there are no strict rules or guidelines regarding the reflector. As such, R-type lamps generally produce a highly diffuse light with a broad angle.

They use a similar nomenclature as PAR type bulbs. For example, an R40 is a bulb 40/8ths of an inch in diameter, or 5". The two most common R-type lamp sizes are R40 and R30.

BR Type Lamps

Preceding the CFL and LED age of high efficiency lighting, the BR-type lamp was an attempt to produce a more efficient indoor-use only replacement for R-type lamps. Standing for "bulbous reflector", the design of a BR-type lamp is more strict. The reflector is designed in such a way as to more efficiently reflect light. They still produce fairly soft, diffuse light, however it is reflected in a narrower beam, thus more efficiently utilizing light produced by the internal emitter (filament, LED, or CFL spiral.)

They too use the same eighth-inch nomenclature as PAR and R type lamps. The most common sizes are BR40 and BR30.

CFL and LED R, BR, and PAR type lamps

While the core design of these types of lamps was implemented in the days of tungsten-filament (incandescent and halogen) bulbs, the design is still used for CFL and LED lamps. In the case of CFLs, the actual reflector efficiency is likely suspect (at least in the case of a PAR type lamp), as the design of a PAR lamp, and thus it's efficiency in utilizing light, is dependent on the size and location of the internal emitters. CFL spirals are usually used in CFL-based flood lamps, and CFL spirals are a very different kind of emitter than a filament or LED. LED based flood lamps probably resemble classic filament based flood lamps better than CFLs do.

LED and CFL Light Quality

In some experimentation of my own, LED-based PAR type lamps definitely seem to direct a far greater quantity of their light downward, where as CFL spiral-based lamps still generally produce a more diffused output. Depending on the type of lens in front of the emitter, the quality and shape of the projected light for both CFL and LED PAR type lamps can vary greatly, from caustic refraction to fairly diffuse. CFL R/BR type lamps nicely simulate their incandescent predecessors. LED R/BR type lamps do not seem to diffuse quite as well as CFLs, so if you are looking for diffuse flood lighting, CFL generally has a more pleasing diffusion.

LED PAR lamps definitely produce a greater amount of directed illumination, so if you need to brightly light anything, LED is probably the best choice. LED flood lamps are also usually fully dimmable, "instant" on (sometimes "instant" really means up to a half-second delay before light is actually emitted), and produce far greater consistency of color (CFL color consistency is often rather poor, and during cooler or cold days, CFL floods will frequently brighten, dim to a deep magenta, then slowly normalize as they warm). LED lamps, of all designs, are usually fully dimmable these days as well. Dimmable LED flood lamps are usually dimmable down to 10% illumination, with some from the better manufacturers (such as Lighting Science) often dimmable down to 5%. Dimming quality, smoothness, minimum output and consistency is vastly superior on LED compared to CFL, with no flicker, popping, blinking, or inconsistent dropout as is frequent with dimmable CFL lamps.

In terms of the quality of projected light, BR-type CFL lamps definitely produce a smoothly diffuse light with little visible pattern directly underneath each bulb. PAR type lamps, either CFL or LED, but more so in the case of LED, produce visible refraction patterns under each bulb. I believe this has a lot to do with the design of the lens, and when multiple flood lamps are used along a hall or in a kitchen, diffusion improves. LED PAR type lamps can be very bright, which is nice when you need light.

My Choice and Recommendation

I have chosen to refurnish my kitchen, and eventually my hallways, with Lighting Science 5000k and 3000k (or possibly 4000k) Dimmable PAR38 LED lamps. These puppies are about $34 each, however they have twice the lifetime rating of comparable lamps from all other manufacturers (50,000 hours @ 6hrs per day vs. 25,000 hours @3-6hrs per day). The light is not as diffuse as your standard R-type incandescent, but the color quality is far superior for those who have never much liked the deep orange color of a classic incandescent (the 3000k versions are closer to a halogen in color, and the 5000k produce a nice, clean, crisp neutral white.)

For the highest quality, I recommend the following. Since LED lamps are dimmable, it is recommended to use a dimming switch wherever you use high lumen LED PAR lamps (i.e. 800 lumen or brighter). Personally I use Lutron HED-certified digital dimmers with dimming setting memory. One push of the button and the lights fade up over about a 1.5 seconds to your pre-set brightness level. Another push of the button, and the lights fade to minimum brightness then off over several seconds. With 800 lumen bulbs, setting a Lutron digital dimmer one or two notches down from maximum brightness produces very pleasing illumination, with the added bonus that if you need more light, or wish to add light during the daytime to fully illuminate areas that might generally be in shadow, you have the ability to crank up the illumination beyond that pleasing level.


PAR = Parabolic Aluminized Reflector.

The number is the diameter of the bulb times 8, so divide by 8 to get its diameter. Thus, a PAR30 is a 3.75" diameter bulb.

Our last house had PAR30 floods in track lighting in the living room (a style that was all the rage when the house was built in the 1980s). You can use them indoors. The quality of light you get is entirely dependent on the bulb. A beam angle of 40 degrees or more will render close to the typical light dispersal we all grew up with. There are some LED floods available, and a few offer a greater than 30 degree beam angle with a diffusing lens at around 3000k color temperature. If you can find some, they can save you a ton of money over the years.

  • Sealed beam auto headlamps are also PAR Commented Dec 3, 2012 at 6:54
  • 2
    Ok...I understand what PAR means in terms of an acronym...that was not realy my question though. How is a Parabolic Aluminized Reflector different from a standard Reflector? What is the quality of the light they project? Are PAR type lamps acceptable for use in, say, a kitchen? I'm asking for more than a one-liner...preferably from someone who has used PAR type lamps indoors who knows how they illuminate and how that illumination differs from standard R/BR type lamps.
    – jrista
    Commented Dec 3, 2012 at 16:27
  • @energydecisions - can you e-mail the team at "[email protected]" and they'll walk you through the registration process
    – ChrisF
    Commented Dec 9, 2012 at 19:12

I have a house that has pretty high (12-13 foot) ceilings with recessed cans. I was using 120 Watt BR40 bulbs (the highest wattage allowed for the cans), and my electric bills were over the top. About 3 years ago, I switched to CFL's, and my bills went down significantly. Unfortunately, my wife did not like the CFL's (light color, long time to turn on, etc, etc, etc). I began to investigate LED's, and have unwittingly become pretty expert in the subject of light bulbs.

PAR38 as REPLACEMENT for BR40-- I found out the hard way that PAR38's are generally about an inch shorter than BR40's, so MAY not fit your can or may look funny (too recessed). I tried some and they could not screw into the can (the bulb threads wouldn't reach the receptacle because of the shape of the baffle and a bulge in the bulb just below the threads). I am going to try a 1 inch screw-in receptacle extender-- hope it fixes the problem.

Note that during my research, I found the following information that even many clerks in the stores didn't understand.

BRIGHTNESS-- this is measured in LUMENS, not watts. It is generally listed on the bulb package. Generally, about 600-800 lumens is what you want for a table lamp, about 1000 lumens for a normal ceiling reflector, and 1200+ lumens for high ceilings. Watts are of concern only to assure that you are not exceeding the wattage limit of the fixture. Look for ACTUAL wattage used, not "COMPARABLE TO".

COLOR-- This is measured in degrees Kevin (K). The higher the number, the cooler (whiter) the light. LED's are available from about 2400K (pretty yellow) to 5000K+ (blue daylight). Color temperature is largely a matter of preference, and many stores have displays that will show you what a room will look like under different temperatures. Most people seem to like about 2700K for bedrooms and sitting areas, and 3000K (like halogens) for "task lighting (putting on make-up, reading, or needle work).

CRI-- This is a measure of how accurate things will appear under this light. This is a highly complex measurement. However, CRI's greater than 80 are OK for general lighting.

Hope that this sheds some light on the situation (pun intended).

  • Great info for a wiki on the subject, bit doesnt answer the question that was asked.
    – Sam Erde
    Commented Jul 6, 2016 at 1:56

This question came up recently for me in a different context. I found the best explanation in this document on PDF page 4, labeled as page 2 in the document: http://www.energy.ca.gov/appliances/2004rulemaking/documents/case_studies/CASE_BR_Lamps.pdf

Essentially, PAR is the only shape you can expect to efficiently reflect light. The others are generic shapes that are not likely to be efficient in lumen utilization.

  • Thanks bcworkz. I found a little more information, and it seems PAR type bulbs, thanks to their lenses, are capable of offering anywhere from an 18° to a 100° beam angle. I guess I'll have to try a couple out and see how they look. I am worried the lens will disperse light in an odd way relative to the nice diffuse manner R and BR type bulbs to.
    – jrista
    Commented Dec 3, 2012 at 21:49

It should be noted that while PAR LED's have the form factor of traditional halogen PAR bulbs, they do not have the parabolic reflectors of traditional PAR's. The light emitting diode cannot be suspended in space, in the middle of a reflector the way a filament can, at least not yet, it has to be mounted on a board. So, all of the light is coming directly from a group of LED's through a lens. This is why they haven't found a way to produce a good narrow spot yet, because the way they did that was by adjusting the shape of the parabolic reflector. I have seen some progress in finally some focusing ability in LED flashlights, so maybe we will get some real PAR spots with a sharply defined pattern in the near future. They don't appear to be available now. I have put PAR LED's in my office and my kitchen, but in my media room where I have to have defined light and dark areas, like accented prints on the walls and no light hitting the TV, I'm going not buy another round of halogen bulbs and hope the technology improves in LED's.


There is a lot of misinformation in the answers provided, in regards to LED bulbs. The difference between PAR & BR LED bulbs is minimal, and mostly cosmetic. Basically, the PAR bulb has a flat surface, while a BR bulb has a rounded surface. Given the same lumens, the same size, the same color temperature and the same lumens per watt, it really does not make a difference whether it's a PAR or BR.

The flat-look PARs may be a little more modern looking, but to simulate an older incandescent-looking bulb with the round, curved glass, I actually prefer the BR bulbs. But it's mostly a choice on the look of the bulb, not the look of the light it produces.

Again, I am just talking about LED bulbs. Answers reflected here (no pun intended) seem to come from information using older incandescent or halogen technology.


If anyone came upon this page looking for stage/studio/video lighting PAR can info, the answers here will be equally helpful to you. So, yes you can interchange some bulbs depending on what the wattage min/max are, especially in home lighting.

But when it comes to stage/studio applications, the best thing to know is that you can dim incandescent, halogen, and LED lamps, but you CANNOT do so with fluorescent lamps/bulbs. (You can also run halogen utility light trees with dimmers too.) That is important to know in stage/studio situations. So, CFL's are a no-no with dimmers. Besides, they lack color consistency and control. Small rooms used for video production benefit the most with being able to dim your PAR can lighting, if that's what you're running.

As always, watch your building's amperage and what rooms and receptacles carry in max power. Don't blow your circuits!

  • 1
    It's not true that you cannot dim fluorescent lamps. There are dimmable models that require a special dimmer. They typically look crummy IMO, but to say its impossible is not true.
    – Steven
    Commented Dec 23, 2013 at 3:53
  • Fluorescent lamps can be dimmed if the ballast supports it -- this is best done with a separate dimming ballast driving garden variety tubes or 4-pin base CFLs along with a 3-wire type dimmer to match, though, instead of trying to use dimmable screw-base CFLs with a standard phase-cut dimmer. (Now I want a 4-pin PAR38 CFL...) Commented Nov 17, 2015 at 5:13

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