(Still Growing!)

Don Klipstein's Lighting Info Site!

Updated 9/21/2023 for linking to other sites, 10/23/2023 for my content.

The most efficient and brightest LEDs! (update 2/25/2024)

The most efficient white lighting LEDs at "full power", or even at any datasheet characterization current, achieve around 150-267 lumens/watt, and that is mostly for neutral white and cool white ones with low or moderate color rendering index. White LEDs that have warm white color (around/under 3500 K) and/or high color rendering index (at least 90) achieve less, 107-170 lumens/watt for achieving both color temperature around/under 3000 K and CRI of 90-plus, and 115-180 lumens/watt for "semi warm white" of 3500 K. The most efficient colored LEDs on the market so far have overal luminous efficacy of approx. 90-235 lumens/watt at "full power", for colors ranging from orangish red to green. This is with "real world practical" thermal conditions, as of 1/18/2023.

Yellowish green / "lime" / "lime green" LEDs can achieve 250-280 lumens per watt but I am not aware of such extreme efficiency LEDs being on the market as of 2/15/2023.

Some green LEDs, both usual unphosphored ones and the less-common latecoming phosphored ones, can achieve around or over 220 lumens/watt and a small number of these can achieve or exceed 235 lumens/watt by being underpowered. Unphosphored green LEDs that have InGaN chemistry generally do well for high efficency while being mildly/modertately underpowered.

Cheaper white LEDs used in some flashlights sold in late 2013 achieved only 30-40 lumens/watt.

LED light bulbs that replace 60-100 watt "A19" standard incandescents mostly achieve 80-105 lumens/watt as of 4/2/2022. The most efficient LED light bulbs that I have seen in retail stores are mostly in IKEA's Solhetta series which mostly achieves 135-138 lumens/watt along with notably high color rendering index (CRI) of 90-92, although two models of this series have more extreme claims of 152-160 lumens/watt. A Feit Electric 150-watt-equivalent LED lightbulb that I saw at Home Depot is claimed to produce 2605 lumens from 18 watts, 144.7 lumens/watt, but I saw that only in two color temperatures and the lower one was 3500K ("bright white").(UPDATED 4/2/2022, slight typo cleanup 5/11/2022)

LED light bulbs that replace reflector flood incandescents or other non-A19 incandescents or incandescents that use 7-50 watts generally achieve 50-100 lumens/watt, (UPDATE 4/2/2022) I have a 5-watt 500-lumen globe one from Dollar Tree that achieves 100 lumens/watt. There are LED nightlights and LED nightlight bulbs that achieve much less luminous efficiency, even less than 10 lumens/watt, but they are energy savers when compared to older tech nightlights that they replace.

For comparison:

"USA-usual" (now banned to manufacture in or import into USA) 100W 120V "A19" 750 hour incandescent - 17.1 lumens/watt. Lower wattages and longer lifetimes achieve less, mostly 10-16 lumens/watt. The halogen replacements have efficiency of 20.7, 19.8, 17.4, and 12-15.2 lumens/watt for 100W, 75W, 60W and 40W replacements respectively.
Compact fluorescents - mostly 45-65 lumens/watt including ballast losses, maximum in the sub-45-watt range is 70 as far as I know.
32 watt T8 fluorescent in "average condition" - typically around 80 lumens/watt including ballast losses.

Lightbulbs that save energy and money! New file 4/4/2022, updated 6/12/2022.

My LED top page, with links to manufacturers, etc. Updated 9/21/2023, external links noted to have updating 9/21/2023.

My page on LEDs that work usefully at low current of .03-3 mA. Updated 2/20/2023.

My page explaining where some big claims of LED efficiency come from, including applications where they are better at outperforming other light sources in efficiency. (updated 5/11/2022)

The Great Internet Light Bulb Book, Part I - Incandescent and Halogen Lamps
An FAQ style "encyclopedia" with answers to most of your questions and other interesting and possibly helpful information.
(Last major change April 1996, minor change 5/29/2006)

Compact Fluorescent Lamps - RESTRUCTURED 5/11/2009 - please see my Compact Fluorescent "Top Page" for links to my compact fluorescent pages. Updated 5/30/2010 (with news of one of the few dollar store models that don't outright rot). NEW NOTE 2/2/2017: LED light bulbs are now more economic and better than CFLs for most purposes. An LED light bulb page is coming here soon!

The USA federal incandescent lightbulb ban of 2012 to 2014 with an expansion in 2022
Including the wide range of exemptions.
(updated 6/4/2022)

NEW 2/15/2010 - s/p ratios of many light sources! (Updated slightly 8/11/2022)

Colors and spectral characteristics of fluorescent lamps.
Includes colored, specialty, UV, and white / whitish fluorescent lamps.
(updated 12/6/2006.)

The Discharge Lamp Article (Great Internet Light Bulb Book, Part II - Discharge Lamps, Volume I - Basic Info) is now here.
Lots of useful information about mercury, sodium, and metal halide lamps as well as "neon" signs and tubing is already here.
(update 12/28/99 V. 1.34)

Some more technical discharge lamp info including references is here! (Possibly A.K.A. The G.I.L.B.B, Part II, Volume II.) First written May 23, 1996 and nowhere near complete.
(Expanded slightly 8/19/2002)(28K)

Some bits of data and facts on some lamps and lighting, mostly but not entirely moderately technical, such as incandescent lightbulbs lasting a century, where to buy these, lower energy efficiency of longlife incandescents, and why higher wattage incandescents are more efficient and why lower wattage incandescents are often made to last longer. Updated slightly 11/19/2017.

Some bits of data and facts on some lamps and lighting, more technical, such as bulb surface temperatures, fixture heating, and number of lumens in a watt of white light. Updated slightly 11/19/2017.

The Sulfur Lamp Document
Much of the knowledge of these lamps that you will find anywhere on the web. (Updated 3/24/98)

Lots of fluorescent lamp stuff by Sam Goldwasser and myself. Includes some info on fluorescent blacklight and other UV lamps, even fluorescent-style germicidal lamps.
(slight update V. 1.90 12/26/99) (long, 99K)

Dimming Fluorescent Lamps! Why it's easy to dim them a little, and why it takes a lot to dim them a lot, especially in a way that is not hard on the bulb. Also a few loopholes.
(updated 6/7/2001)

Electronic ballasts! Lots of links, especially for powering fluorescent lamps from low voltage DC. A bit on-site, including a way to power mercury lamps from low voltage DC (built and tested). Links include electronic ballast stuff in general including line powered ballasts. (updated 12/11/2006, a little more 6/8/2022)

Now, a UV and UV lamp document! Includes EPROM erasing lamps and (roughly) effectiveness of alternatives. Also includes notes on blacklights, sunlamps, and other UV lamps.
(Updated slightly 5/27/2020, most stuff here is pre-2007.)

Carbon arcs for fun and danger!
Some basic info about carbon arcs. For information and your web reading pleasure! These have hazards, and you might not want to try this at home.
(Last change 9/24/96)

Short Arc Lamps - you're wondering about these? They have a small, very intense arc in mercury and/or xenon. Due to high cost, short life expectancy, hazards and often fussy operating requirements, they don't make good toys for casual experimenters. Some of the messy details are here!
WITH MANUFACTURERS, updated 3/1/2010, updated very slightly 11/27/2021.

Xenon flashlight lamps / bulbs and others that are actually incandescent ones with a xenon gas fill. Updated 10/5/2000.

Some odd lamps desribed here including how to make them work. Green "neon" lamps, multicolor "neon" tubing, electroluminescent lights, and spectrum tubes are mentioned here in great detail. Look for more here in the future! (updated 11/18/2017)

I have tested some night lights and lower wattage energy saving odd sorts of lights - and at times I was disappointed. Go to my Night Light Test Results Page to find out how some are less than they lead you to think that they are. (Updated 3/29/2011)

Where to get lamps / lightbulbs!
Get decent plain ones for less, get UV lamps and specialty ones. Info on retail chains in the USA and a few suppliers with web sites.
(Minor update 10/5/2017)

Troubleshooting things that go wrong! Lightbulbs burn out too quickly? Fluorescent lamps acting up? Look here! (updated 11/20/2006)

My top page for all my xenon stuff such as strobes, flashes, xenon arc lamps, strobe hacking, etc. (updated 10/27/2023)

Automotive HID lamps, AKA xenon headlights, etc. New file 2/15/2000 updated slightly 12/3/2011 and 11/27/2021.

Electrical characteristics of a few HID lamps for experimenters, hackers, ballast homebrewers and basement bombers. Includes normal operating arc voltage, minimum arc voltage during warmup, starting voltages, and allowable warmup currents for many popular HID lamps.

My discussion of low wattage HID lamps - why there is no 5 watt or 1 watt HID lamp. (updated slightly 3/23/2009)

How long can a lightbulb last? How easily can they be made to last longer? Why they don't? (updated 4/13/2010)

updated significantly 4/30/2012.

Performance of incandescent lamps at various voltages. So far, current, color temperature and light output as a function of voltage for the 100 watt 120V 750 hour 1750 lumen A19 as well as current as a function of voltage for vacuum T12 and gas filled A19 25 watt 120V lamps. New file 1/2/2006, major update 4/25/2020, minor updaye 11/7/2022. Color temperature and light output of the 100 watt lamp noted here was found to vary slightly less with voltage than previously determined in 2006-2011.

Please read my Copyright Info and my Disclaimers.

Links to other sites I consider worthwhile:

The notable Kilocat's Antique Light Bulb Site, which now even has a forum!

James Hooker's Online Museum of Historic Discharge Lamps

Daniel Stern's automotive headlight site was found not working 9/8/2020.

JKL Lamps, a maker of miniature cold cathode fluorescent lamps and other miniature lamps.

Philip G. has lots of stuff, much is interesting! NOTE - This site was decommissioned and most of the info there is now available at http://www.repairfaq.org/

The spectra site of Ioannis Galidakis

The Lightbulb section of Jim Evan's home repair site.

Sylvania's lighting site.


The Lighting Research Center at Rensselaer Polytechnic Institute.

The Lamptech home page.

FX Lighting.

As for references for lighting related stuff, I learned a good portion of what I know from books with Library of Congress call numbers around TK4000.

I appreciate feedback. Go ahead and drop me a line! I read all non-"SPAM" e-mails, but sorry I can't reply to all legitimate e-mails!

Back to Don's Home Page.