How Many Lumens Is A 100 Watt Bulb?

Incandescent light bulbs were, for decades, common light sources at homes, converting some of the electric energy into light and the rest of the energy into heat.

100 Watt incandescent bulbs were typically used as single bulbs or in pairs for lighting up rooms and similar areas. With the introduction of more energy-efficient light sources, many people wonder how many lumens a 100W bulb produces...

Published: October 17, 2022.

Light Wattages vs. Lumens Luminous Flux

There is no ideal light source that converts 100% of energy into light - all light sources convert some energy into light (good) and some energy into heat (not good).

Depending on the technology, the energy efficiency of light sources varies significantly.

The following comparison chart lists typical lumens (Luminous Flux) for various light sources and their electric power consumption, which is provided in Watts:

As one can see, 100W incandescent light bulbs based on the Tungsten (Wolfram, W) filament feature ~1600 lumens.

Other light sources that have an output of 1600 lumens require:

• Incandescent Halogen Bulb: ~72 Watts,
• Fluoroscent Tubes: 24-28 Watts,
• LED lights: 14-17 Watts.

Reasons why Tungsten incandescent lights are still used, despite low energy efficiency, are their low price and the light color.

Fortunately, with time LED light bulbs have become fairly cheap, and thanks to different light colors, one can easily find the one that best fits one's needs.

Replacing incandescent light bulbs can lead to energy savings, and energy savings mean money savings, right?

LED Lights: Money Savers?

Many people wonder if replacing 100W Tungsten bulbs with ~1600 lumens ~15W LED lights lead to money savings and, if it does, how much.

Example:

If one 100-Watt incandescent bulb operates 8 hours per day, 30 days per month, then:

E = 100W * 8h * 30 days = 24000 Wh / month = 24 kWh / month

The price of electric energy varies, but if we assume the average price of 0.15 $US per kWh of electric energy, that means that a 100W bulb running 8 hours per day, every day during the month, spends electric energy worth 3.60 $US.

One may say that 3.6 $US is not much, but in every average house or apartment, several light bulbs are turned ON even longer than 8 hours per day.

If such 100 Watt incandescent light bulb is replaced by 15W 1600 lumens LED light bulb, then:

E = 15W * 8h * 30 days = 3600 Wh / month = 3.6 kWh / month

and with an assumed average price of 0.15 $US per kWh of electric energy, the cost of running such LED light is 0.54 $US.

So, if we replace a 100W 1600 lumens incandescent light bulb with a 15W 1600 lumens LED light bulb, we may save ~3.06 $US per month.

Since single 15W 1600 lumens LED light bulb costs 2-6 $US, such an LED light bulb pays for itself after 1-2 months.

Note: When looking for LED bulbs, check the temperature of the light and don't go cheap - in our example, we used the average power of an LED bulb of 15W, but there are many models that require even less energy...

Long Story Short: Replacing a 100W 1600 lumens Tungsten incandescent light with a modern 1600 lumens LED light can lead to significant energy savings, especially when several light bulbs are being replaced at the same time.

Also, such a replacement can lead to money savings since LED lights, on average, need 1-2 months to pay for themselves...