## How to convert lumens to watts?

What Are Lumens?
In contrast to watts, lumen is a measurement of light that is more appropriate for consumers. Lumens measure the output of light. In other words, lumens tell us how bright the light produced by a bulb will be.

You can see today that most modern bulb packaging show the number of lumens, which by definition seems like a better indicator for brightness decisions that consumers make for their households.

You can roughly know about how many watts in a bulb can produced the required brightness only by plugging it in the socket. But with the new lumen measurement, you can know exactly, without guessing, the brightness of light a certain number of lumens will produce. Let’s consider some examples that compare and convert watts to lumens:

• A 40-watt incandescent bulb equals around 450 lumens
• A 60-watt incandescent bulb equals 800 lumens
• A 100-watt incandescent bulb equals 1600 lumens

Lumens measure how much light you are getting from a bulb. More lumens means it’s a brighter light; fewer lumens means it’s a dimmer light.

Lumens are to light what

Lumens let you buy the amount of light you want. So when buying your new bulbs, think lumens, not watts.

The brightness, or lumen levels, of the lights in your home may vary widely, so here’s a rule of thumb:

To replace a 100-watt incandescent bulb, look for a bulb that gives you about 1600 lumens. If you want something dimmer, go for less lumens; if you prefer brighter light, look for more lumens.
Replace a 75W bulb with an LED bulb that gives you about 1100 lumens
Replace a 60W bulb with an LED bulb that gives you about 800 lumens
Replace a 40W bulb with an LED bulb that gives you about 450 lumens

What Are Watts?
Watts measure the amount of electrical power used to light a bulb. Essentially, by that definition it means that the more watts a bulb show the more power it will consume to produce light. So a 200 watt bulb will use more power than a 100 watt bulb, giving just a little bit better and brighter light. It is certainly not a good deal for consumers, especially with more energy efficient options available these days.

However, you can’t make the best choice unless you understand the difference. So let’s carry on. It is also said that these bulbs use only 10% of the electrical power to produce light while wasting the remaining 90% in producing heat. So essentially bulbs that give a watt reading are just letting the consumer know how much electrical power it will consume. The brightness of light or the output is up to the consumer to determine once they plug that bulb in the socket.

For comparison sake, let’s understand what is meant by lumens?

Convert lumens to watt
Lumen is the unit of luminous flux and indicates the total amount of light emitted by the light source. Wattage indicates the amount of energy consumption of a lamp. As lights are becoming more and more energy-efficient, the wattage at the number of lumens become lower and lower. For example, to replace an incandescent lamp with LED , the amount of lumens must be compared. With the table below you can easily compare watt with lumen.

Lumens to watts brightness

The brightness, or lumen levels, of the lights in your home may vary widely, so here’s a rule of thumb:

To replace a 100-watt incandescent bulb, look for a bulb that gives you about 1600 lumens. If you want something dimmer, go for less lumens; if you prefer brighter light, look for more lumens.
Replace a 75W bulb with an LED bulb that gives you about 1100 lumens
Replace a 60W bulb with an LED bulb that gives you about 800 lumens
Replace a 40W bulb with an LED bulb that gives you about 450 lumens

Watts and Equivalent Watts

Watts are a measurement of power consumption. With traditional incandescent light sources typically the higher the wattage, the brighter the light. With energy efficient bulbs such as LED this is somewhat different because there is no hard and fast rule to correlate Wattage with output. For example one brand’s 9 Watt LED bulb may emit enough Lumens to replace a 60 Watt incandescent but another brand may need to use a less efficient LED, lets say 12 Watts worth to create enough lumens to replace a 60 Watt bulb. This is why as we mention above, it is more important to take a look at Lumens versus Watts.

Many household and commercial fixtures were not designed with LED bulbs in mind. They typically feature warnings that indicate “Fixture designed for a XXX max Watt bulb”. These are heat ratings designed to prevent users from placing a higher wattage bulb inside of the fixture than what it was designed for. LED bulbs consume far less wattage and consequently, produce less heat therefore a 60 Watt equal LED bulb could be safely used in a fixture rated for a 40 Watt incandescent, same goes for using a 75 Watt equal LED bulb in a fixture designed for 60 Watt incandescents.

When we describe the “Wattage Equivalent” of a LED bulb this is a simple way of letting shoppers know what level of output this bulb will provide at a glance without having to dive deeper into the Lumen specification but it remains Lumens should be your guide when measuring the total output of a particular light bulb.

Lumens to watts comparison

Measuring Brightness

It has become common and ingrained in our minds to think of how bright a light bulb or light fixture is based on its wattage. A 60-watt bulb meant you got 60 watts of light. That’s how it’s been for decades. But watts are not a measure of light output. Rather, they are a measure of how much energy a light source is consuming.

What we’re after here is brightness; the amount of light emitted by a light source. How bright is that light bulb or fixture? How much light is it giving off? The unit of measurement to determine how much light a lamp or luminaire emits is called lumens.

The lumen output is what determines brightness and is the term and measurement we should all start to get very familiar with.

Older incandescent bulbs converted their used energy into visible light at a predictable rate (albeit terrible), so we were very familiar with it. But new LED technology is changing all that; requiring far less energy to give off the same amount of light. And with LED technology constantly evolving and becoming more efficient, it is becoming more and more important that we become comfortable with lumens.

Comparing the Different Technologies

So how do these all stack up? How many lumens did a traditional incandescent 60-watt light bulb give off? What’s the modern LED equivalent?

Time for charts!

Scaling Up

It is worth noting that as you scale up and start getting into larger bulbs and light fixtures with more intense light output, additional factors come into play when comparing different lighting technologies and you need to look beyond simply the lumen output.

Directionality is one such factor. This is increasing common in commercial and industrial applications. For example, suppose you have a parking lot light that uses a 250-watt metal halide HID lamp. That 250-watt bulb outputs roughly 14,000 lumens (on average) in all directions. But you don’t need the light in all directions; you only need the light down on the surface of the ground. With traditional lighting, a good percentage of light is lost before it hits the ground, often escaping into the fixture housing or diffusing as it bounces around the housing’s reflectors. The intensely powerful and energy-consuming HID lamp is needed in this case so that enough of its light makes it down to the ground.

Suppose you want to upgrade that same parking lot light fixture to LED. Does this mean you’d need to find an LED area light that outputs the same 14,000 lumens? No, not necessarily. Because LEDs are inherently directional, all of their light is pointed towards the target surface (in this case, the ground). Depending on the situation, you might be able to use an LED fixture that outputs only 7,000 or 10,000 lumens.

There are many other factors that affect the light output of a fixture or bulb, called Light Loss Factors. These include ballast factor, ambient temperature, voltage, optics, burnouts, lumen depreciation, and more.

While it can get confusing at first to try and factor them all in to create a true apples-to-apples comparison of high-output fixtures and lamps across different lighting technologies, the bottom line is that often you will be able to use an LED that, on paper, has less lumen output than the traditional light source. So not only will you save energy by simply switching to LEDs, you will likely be able to step down to a lower output fixture because of the increased optical efficiencies of LED fixtures, while maintaining the same foot candle levels at the target surface.

Naturally, this can vary greatly per project, depending on various conditions. But as an overall guide, here are some common equivalents. Note the difference in lumen outputs.

 Initial Lumens Mean Lumens Metal Halide Lumens LED 3400lm 2000lm 50w 1000lm 10w-12w 5600lm 3700lm 70w 2000lm 15w-20w 8500lm 4600lm 100w 2500lm 20w-25w 10000lm 6000lm 125w 3200lm 28w-30w 11000lm 8000lm 150w 4600lm 36w-40w 15000lm 9000lm 175w 5800lm 45w-60w 22000lm 14000lm 250w 7000lm 54w-70w 36000lm 22000lm 400w 14000lm 100w-120w