Conversion Lumen To Watts Made Easy: How to Convert Lumens To Watts? [2022 Updated]

The innovation of LED lights from incandescent bulbs is huge. An upgrade from having the regular LED bulbs from the incandescent lights speaks up a lot because of the unnecessary consumption of wattage or lumens.

Most LED lights last for 50,000 hours before they become dim, which is 50 times the life of your current globes, you may never have to replace them in your lifetime! But conversion lumen to watts get’s very confusing for everyone. Let’s get started with this. 

What Are Lumens?

The exact definition of lumen is the measurement of the visible light and the amount of emerging light coming out from the source. It can be from anything either from a simple bulb, a candle or any source of light.

For example, a light bulb that produces 100 lumens will produce the same amount of light as 100 candles from one foot away.

The efficiency of a light source can be worked out based on its lumen-to-watt ratio (lm/W), which, in other words, is the amount of light (lumens) given off for each watt of electrical energy consumed.

Most incandescent bulbs achieve about 17 lm/W, while CFLs (Compact Fluorescent Lamps) can manage between 35 and 60 lm/W.

However, a typical LED Light will easily manage 160 lm/W, with some prototype models reaching a staggering 200 lm/W.

This means that LED lights produce a lot more energy while consuming less energy, resulting in a light source that is cheap to run and environmentally friendly.

LED Tapes are no exception to this rule. The light output of an LED Strip can be expressed in one of two ways.

Usually, retailers will provide the lumens per meter of their strip. Still, it is also possible to calculate how many lumens are given out by each individual LED chip for a more accurate measurement.

Lumens to Watts Calculator Help

General Lighting for this restful Bedroom retreat, we’ll calculate 15 Lumens per square foot. General Lighting (see chart) lights the middle 3′ of an average room with 9′ ceilings.

18′ x 17′ = 306 sf

We’re recommending 15 Lumens per square foot for a more restful area.

306 square feet x 15 Lumens per SF is 4590 Lumen

Divide 4590 by 1690 (1 average Incandescent Bulb)

You need 2.92 Bulbs rounded up = 3 / 1690 Lumen (100 watt) incandescent bulbs

This being said, many light sources tend to “spill” light, meeting that a 100-watt incandescent bulb efficiently lights about 75% of our 15 – 35 lumens per square foot.

So the correct formula is:

Several lumens – divided by the wattage x.25 (to compensate for Light spill) = NUMBER OF BULBS NEEDED.

To achieve Ambient Lighting (see the chart), add dimmable recessed lighting or track lighting. A typical 4-inch fixture is spaced 4 feet apart (6″ fixtures about 6 feet apart). For the sake of discussion, let’s use a 40-watt incandescent bulb from the chart.

306′ divided by 4′ (4″ recessed cans spaced 4′ apart)= 76.5 s.f.

76.5 s.f. divided by 40 (watts) = 5.1 bulbs (5 bulbs)

Now, If 5 bulbs efficiently light 75% of each square foot (due to light spill)

75% of 5 (use 5 fixtures x.25; it’s correct and easy) = 1.25, so you need 1 extra fixture:

Our Master needs 6 40 watts recessed cans to get 15 LPW per square foot.

You can check this lumen to watts calculator app as well.

Conversion Lumen To Watts

The 100-watt bulb was a lot brighter than the 40-watt bulb. To give you some guidelines, you can convert the old incandescent wattage to the newer measure of lumens as follows:

40 watt incandescent = 450 lumens

60 watt incandescent = 800 lumens

100 watt incandescent = 1600 lumens

The good news about the new technologies is that you get more light for less wattage. The compact fluorescent bulbs use about 23 watts, and the LED bulbs use about 16 watts of electricity for a comparable 100-watt incandescent bulb.

So whether it is watts versus lumens, you are getting much more efficient with the fluorescent or LED bulbs.

Convert Watts To Lumens

The output of light is measured in Lumens per watts (LPW). The recommendation for lighting per square foot varies by task, and guidelines vary by state.

But let’s oversimplify and go with an average of between 15 – 35 Lumens per square foot, depending on the home “zone” you’re lighting.

It stands to reason that you need brighter task-oriented lighting in work zones (kitchen, living, office) with more restful lighting levels in bedrooms.

Lumens To Watts Converter (Comparison Table)

LumensHalogen lampLEDLight bulbEnergy-saving lamp
230 – 270 lm19 watts2 – 3 watts25 watts6 watts
430 – 450 lm35 watts4 – 6 watts40 watts9 watts
730 – 800 lm50 watts7 – 9 watts60 watts13 watts
1380 – 1600 lm84 watts12 – 14 watts100 watts23 watts
1500 – 1800 lm98 watts15 – 17 watts120 watts32 watts
2000 – 2500 lm122 watts18 – 23 watts150 watts40 watts

Watts To Lumens Conversion

With the old measurement of watts, consumers got a rough estimate of how much light a bulb would give off. More watts logically imply more light so that a 100-watt bulb would be brighter than a 40 watt.

However, this type of measurement is only relative, as watts indicate how much energy a particular bulb uses, rather than how bright the light will be.

In contrast, lumens are a measurement of the light output of a bulb. The more lumens a bulb is rated, the more light you can expect to get out of it.

For the average consumer, this is a huge paradigm shift. Figuring out the number of lumens necessary to light up a room is a more difficult problem for consumers to solve these days than ever before.

Important Notes For Lumen To Watts Conversion

You probably have 60W incandescent lights, which gives off about 700 lumens or just 13 lumens per watt. Ever tried to change one of these after it has been on for a while?

You’ll be well aware that they get boiling. Yes, most of the electricity generates heat, not light, so they are very inefficient bulbs.

Keep your eye on this technology. It will reduce your lighting bill by at least 40%, and in a few years, this could mean you cover the costs of buying them in 3 months.

Not to mention the environmental benefit of using less power, which reduces carbon dioxide emissions too.

How Many Lumens Do You Need?

In general, the more lumens you have from one or more light sources, the more lit up the room will be. Of course, this can create a range of problems, from too little to too much light, or light of the wrong color temperature that makes the room in general or certain objects too “warm” or “cool” for one’s taste.

So how many lumens do you need in a room? Unfortunately, there is no one-size-fits-all answer to this question. 

One good rule of thumb is to overshoot the number of lumens you need for a living or bedroom and install dimmers to control the light output. While all incandescent and halogen bulbs are dimmable, check manufacturers’ dimmer compatibility lists for household LED bulbs or look for a CFL that specifies it is dimmable.


Start with the size of the room and work from there. The number of lumens necessary to light up a room is highly dependent on the square footage of the space, how high the ceilings are, the color of paint on the walls and furniture, and how far the people in the room will be from the light sources.

We hope that this tip will help you while doing the conversion lumen to watts. Still, if any doubt arises fell free to reach us in the comments.

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