Lumens to Watts Calculator
You can use our lumens to watts calculator to calculate the efficiency of different bulbs and low wattage LEDs based on their brightness to power ratio, known as luminous efficacy, where the brightness of the light is in lumens and its power, in wattage.
You can then compare your LED bulb wattage with other light bulbs to observe how much electricity you'll save. And to further reduce your electricity bill, you may try our outstanding appliance wattage calculator.
Furthermore, we will tell you how to calculate lumens to watts using a formula and show you a comparison chart of LED wattage consumption against other bulbs.
Features of lumens to watts calculator

We can use this lumens to watts calculator to find the required LED bulb wattage, i.e., the power needed for our light bulb to produce the specified amount of visible light, based on its luminous efficacy.

You can also use it to find the luminous flux, i.e., the brightness of light that our bulb produces with a given amount of power and luminous efficacy.

Finally, we can find the luminous efficacy, i.e., how efficiently our light bulb produces visible light based on its power to Lumen ratio.
How to calculate lumens to watts using this calculator
Here's how we use the lumens to wattage calculator for LED lights.
 Enter the luminous efficacy of your light source. The default is at 100 lm/W, primarily for LEDs.
🔎 You can find your value from our light bulbs efficiency chart below if you have a different light source.
 Enter the brightness of your LED in lumens or nits, e.g., 1200 lumens or 350.25 nits. It is usually mentioned on the packaging of the bulb or you know the lumens of the old bulb you want to replace.
💡 Nit generally measures the brightness of digital displays, such as mobiles, computers, or TVs. For reference, the sun at noon measures about 1.6 billion nits.

Once you have entered your bulbs luminous efficacy and brightness, you'll determine how much power or wattage your light source requires.
Thus, with a luminous efficacy of 100 lm/W, for producing 1200 lumens, the required power is 12 watts.
Light bulbs efficiency comparison chart
The following table shows a range of luminous efficacies for different light bulbs:
Light bulb type  Luminous efficacy (lumens/watt) 

LED bulbs  80120 
Compact fluorescent bulbs  4575 
Fluorescent tube lights  40105 
Highpressure Sodium  85150 
Lowpressure sodium  100190 
Sulfur plasma lights  50100 
Metal halide lights  75100 
Mercury vapor lights  3565 
Halogen light bulbs  1630 
Tungsten Incandescent bulbs  1218 
Because different manufacturers have different standards, there are variations in lumens to watts ratio for the same light sources.
You can also try our lighting calculator to determine how much lighting you'll require based on the dimensions of your surface.
How to calculate the wattage of LED lights and other bulbs manually
Based on their brightness and efficiency, we use the following formula when we want to find the required wattage of our lowwattage LED bulbs:
where:
 $P$ – Power required, in watts;
 $\varPhi _{V}$ – Luminous flux or the brightness in lumens (lm); and
 $\eta$ – Luminous efficacy or the efficiency of producing visible light in lumens per watt (lm/W).
As an example, let's find the required wattage of an LED that has a luminous efficacy of 120 lm/W, and produces 1200 lumens:

Placing the values in the formula, we get:
$P _{(\text W)} = 1200 / 120 = 10$

Thus, our LED requires 10 watts for producing 1200 lumens.
💡 Standard LED luminous efficacy is between 80 and 120. However, some specific LEDs take this luminous efficacy up to 200 lm/W.
Let's take another example where we wish to find the luminous efficacy of our bulb, which consumes 15 watts and produces 1000 lumens:

In order to find its luminous efficacy, we rearrange the formula as follows:
$\eta _{(\text{lm/W})} = \varPhi _{V (\text{lm})} / P _{(\text W)}$

Placing the values in the formula, we get:
$\eta = 1000 / 15$

Thus, our bulb's luminous efficacy is 66.67 lm/W.
In case there is no mention of wattage on a device, we multiply its voltage by the electric current in amperes, i.e.,
$\text{Wattage = Voltage × Ampere}$
How to compare wattage of LED to incandescent and other bulbs
Here's an LED wattage chart comparing a lowwattage LED bulb of 12 W at 100 lm/W against other bulb types with different luminous efficacies.
Light bulb type  lm/W  Power consumption 

Tungsten Incandescent bulb  15  Requires almost 7 times more power 
Halogen light bulb  20  Requires almost 5 times more power 
Mercury vapor light  50  Requires almost 2 times more power 
Fluorescent tube light  60  Requires almost 1.7 times more power 
CFL light bulb  70  Requires almost 1.4 times more power 
Sulfur plasma light  75  Requires almost 1.3 times more power 
Metal halide light  85  Requires almost 1.2 times more power 
✅ The chart tells us that the equivalent wattage of an LED to an incandescent light bulb is almost 7 times less for producing the same amount of light.
Disclaimer: This LED wattage chart only represents approximate values, as different manufacturers have different standards.
FAQ
How do I calculate the wattage of an LED strip?
You can multiply the required voltage by amperes (current) to obtain the wattage.
watts = volts × amps
Or you can divide the lumens, i.e., the brightness of the LED strip, by its luminous efficacy to obtain the wattage.
η = lm / W
where:
η
– Luminous efficacy;lm
– Brightness in lumens; andW
– Power in wattage.
How do I convert 500 watts to lumens?
To convert 500 watts to lumens:
 Find the type of bulb to determine its luminous efficacy.
 Then multiply the wattage of the bulb with its luminous efficacy to obtain lumens.
For example, if our 500 watts bulb has a luminous efficacy of 40 lm/W: The amount of light it can produce will be 500 × 40 = 20,000 lumens
.
Can we use higher wattage LED bulbs?
Yes, as long as your LED wattage doesn't exceed the maximum recommended power load on your fixture or wiring, you can use higher wattage LED bulbs. Be careful not to overload, as that may damage your wiring due to excessively generated heat and cause shortcircuiting before catching fire.
How does LED wattage compare to incandescent light bulbs?
The wattage consumption of LED is roughly 7 to 10 times less for producing the same amount of light compared to incandescent light bulbs.
Divide the lumens, i.e., the brightness of a light bulb, by its luminous efficacy to obtain this wattage:
watts = lumens / luminous efficacy
Why are bulb lighting colors in Kelvin?
The bulb light colors artificially mimic the Kelvin temperature of a metal object when it’s heated, ranging from 1000 K to 10,000 K.
Lower numbers have warmer tones, while higher numbers have cooler tones.
We generally use between 2700 K to 4100 K lights in our daily lives.