Lumens vs Watts

[skee0025]

Over the winter I plan to start replacing all of the light fixtures in the house with LEDs. The problem I am running into is finding a lumens to watt comparison chart. An example would be a fixture I am looking at right now. It states it has a 1000 lumen output of bright white light, which means nothing to me... I have nothing to campare this to in terms of known light output. Is it equal to a 40W, a 60W or a 100W incandesant bulb. Any help would be great, thanks

[JohnMickish]

Unfortunatly there isn't a lumen to watt converstion chart.

A Watt is the measurement of power.

A lumen is the measurement of light.

I'll try to explain it a little bit. A 65 watt incandescent bulb uses 65 watts at 120v to burn the filiment at the desired intensity. The lumen output depends on many things. A clear glass bulb will have more lumens than a frosted glass bulb at the same distance. A bright or daylight bulb will have more lumens than a warm color bulb. Look for the color number on the package, something like a 2900K is close to a warm color, while anything above 3500K is considered daylight or bright light. A spot will have more lumens directly under it than a flood will, but move three feet to the side and a flood will have more lumens than a spot will.

With LED lights it is very difficult to know what you are buying before you buy it, and they won't take it back. With that, I will say that 1000 lumens is pretty darn bright! I am guessing that a light like that will havea pencil beam to it. Don't quote me on this, but I am thinking that OSHA requires 70 lumens/square ft for a work space.

In the past few years I have installed litterally thousands of LED fixtures and retrofits. Some customers are very happy and some are not so happy with the light.

[aanderud]

It states it has a 1000 lumen output of bright white light, which means nothing to me... I have nothing to campare this to in terms of known light output. Is it equal to a 40W, a 60W or a 100W incandesant bulb. Any help would be great, thanks

The reason they put it in terms of lumens is that it's a measure of light, rather than power draw. Different lighting technologies draw differing amounts of power to create the same light output. So, rather than comparing power draw (which varies depending on if it is incandescent or led or flourescent), people compare light output to get apples to apples. If you find two bulbs that output the same number of lumens, they will be essentially the same brightness no matter how much power they are drawing.

For comparision then, older tungsten 120 volt incandescent bulbs of 40 watts would output roughly 450 lumens, and 60 watt bulbs output roughly 800-900 lumens, and 100 watt bulbs output roughly 1600-1750 lumens.

Most high efficiency bulbs list not only the number of lumens but also the rough equivalent in "incandescent" watts. For example, a 12 to 13 watt CFL bulb might state on the box that it outputs like 1000 lumens and is a "75 watt equivalent" bulb. (I don't have any in front of me so I made those numbers up)

[Whoaru99]

John is quite right there is no direct conversion due to many variables.

However, for a few point of reference to plain old bulbs...

A box of GE soft white 60W bulbs says 840 lumens, a box same bulb in 40W says 490 lumens, and a GE soft white 3-way says 50W, 615 lumens; 100W, 1540 lumens; 150 watt, 2155 lumens.

[skee0025]

Thanks for the input, that gives me something I can use.

[Tom7227]

I just bought an LED bulb for a light that is on quite a while at night. I think it cost $17 or so. It gives off a nice color light and is plenty bright enough for my use. The package said it will last 28.2 years, which I doubt anyone will ever test.

I am not so sure about the economics of the LED. If I were to need a bulb in a place that was hard to get to then I would be more comfortable with the cost. Any of you math types figure out when the bulb will make sense economically? Any of you real wizards out there know if I'll still be alive at that point?

[delcecchi]

BTW the light output per watt is variable depending on how hot the filament is run. Cooler filament lasts longer but puts out less light per watt.

I just looked at a GE soft white 3way 30/70/100 and it is 305/995/1300 lumens. If you look at a long life bulb you will see it puts out fewer lumens.

[masoct3]

I can tell you that the higher lumens will be bright white LED. So if you have a dining room that you have a few lamps and a chandelier, its going to be pretty bright. But personally, I like the "bright white" option the best. Some others are daylight, soft white.

[cavalierowner]

I just bought an LED bulb for a light that is on quite a while at night. I think it cost $17 or so. It gives off a nice color light and is plenty bright enough for my use. The package said it will last 28.2 years, which I doubt anyone will ever test.

I am not so sure about the economics of the LED. If I were to need a bulb in a place that was hard to get to then I would be more comfortable with the cost. Any of you math types figure out when the bulb will make sense economically? Any of you real wizards out there know if I'll still be alive at that point?

Before I retired a couple years ago, I went to a seminar about LED's. One of the things the engineers addressed were the long life spans of the LED's. They said that the LED's would indeed be still burning at the number of years stated, but the amount of light would be significantly reduced. If I recall, the amount of light reduction would begin to be noticeable at about 2/3 of the stated life. Still a pretty impressive life though. The engineers stated that, while LED's are still a long way from taking over, they think LED's are the way lighting is headed; it just needs some more time for technology and pricing to make them more feasible. BTW, my wife bought 4 LED floods for some track lighting; we tried using them for about 2 months and took them out because there was not nearly enough light despite what it said on the packaging. It was a VERY expensive experiment!

[Whoaru99]

Just FYI/FWIW, often you'll note that "long life" bulbs are rated at 130V, not the standard 120V. That's why they're long life. They're being run in a de-rated state, and to your point why they don't put out as much light.

[shizzy]

I just bought an LED bulb for a light that is on quite a while at night. I think it cost $17 or so. It gives off a nice color light and is plenty bright enough for my use. The package said it will last 28.2 years, which I doubt anyone will ever test.

I am not so sure about the economics of the LED. If I were to need a bulb in a place that was hard to get to then I would be more comfortable with the cost. Any of you math types figure out when the bulb will make sense economically? Any of you real wizards out there know if I'll still be alive at that point?

I only replace Burned out Incandescent bulbs in my house with CFL's for this reason. I never bought in to the "replace them all right now!" theory. I haven't yet started buying LED's (cost reasons) but, I feel it makes more financial sense to not remove a fully functioning 99 cent bulb to replace it with a $3+ bulb.

[delcecchi]

Bet you can get a substantial rebate on that bulb from the electric company. Works for both LED and CFL.

http://www.xcelenergy.com/Save_Money_&am...ting_-_CO_MN_NM

[bobbymalone]

Bet you can get a substantial rebate on that bulb from the electric company. Works for both LED and CFL.

http://www.xcelenergy.com/Save_Money_&am...ting_-_CO_MN_NM

I bought a box of CFLs at the big orange home improvement store over the weekend and noticed that some of the prices were labeled as subsidized by Xcel energy.