Battery Equivalents and Replacements

Light Bulb Wattage: How Many Watts Does A Light Bulb Use

Light bulbs are smallish devices that convert electric energy into light and heat, and until a few years, not many people wondered about their energy efficiency.

But, with the rise of electric energy prices, and the introduction of newer light bulb technologies, many people ask themselves how many watts their light bulbs actually use and if it is worth to start using new, energy very efficient LED bulbs.

Published: November 24, 2022.

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Light Bulb Types and Power

When talking about light bulb wattage, one must first figure out the exact type of light bulb and find its nominal power, given in Watts.

The most common light bulb types are:

  • Incandescent (Tungsten)
  • Incandescent (Halogen)
  • Fluorescent
  • LED

The actual power requirements of the light bulbs are often written on the box and the light bulb itself. Also, manufacturers write down the light bulb's luminous flux (given in lumens) and other information, if available or required, like energy efficiency calls, light temperature (LED light bulbs), and similar.

The following comparison chart lists typical luminous flux (lumens) for various light sources and their electric power consumption (given in Watts):

Lumens Incandescent
(Tungsten)
Halogen
Incandescent
Fluorescent LED
90 15 6 2-3 1-2
 200  25   3-5  3-4
 450  40  29  9-11  5-8
 800  60    13-15  8-12
 1100  75  53  18-20  10-16
 1600  100  72  24-28  14-17
 2400  150    30-52  24-30
 3100  200    49-75  30-36
 4000  300    75-100  40-45

As one can see, various light bulb technologies require different amounts of energy in order to produce the same amount of light.

At the moment, light bulbs based on Light Emitting Diodes (LEDs) are the most energy-efficient light bulbs.

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Incandescent (Tungsten) vs. LED Light Bulbs

Incandescent light bulbs based on the tungsten overheated filament were, for many decades, the only type of light bulb used in homes, offices, and similar areas.

However, LED light bulbs are much more energy efficient, and people want to replace their incandescent light bulbs with LEDs.

But are they worth it?

If we compare two light bulbs that are both producing 1600 lumens, we find out that an incandescent light bulb requires 100W of electric power, and an LED light requires ~14W.

If those light bulbs are used 8 hours per day, 30 days per month, that is 240 working hours. During one month, these light bulbs require (assuming $0.15 for 1 kWh of electricity):

Incandescent Light Bulb → E = 240h * 100W = 24000 Wh = 24 kWh = $3.6

LED Light Bulb → E = 240W * 14W = 3360 Wh = 3.36 kWh = $0.504

So, if we replace one 100W incandescent light bulb with a 14W LED light bulb, one can save ~$3 per month if those light bulbs were/are running for 8 hours per day.

Thus, replacing old light bulbs with new LEDs will pay off in just 1-2 months.

Similar calculations can easily be done for other wattages as well.


Long Story Short: If You have old incandescent (tungsten or halogen) light bulbs, replacing them with new LED light bulbs will save plenty of energy and decrease your electric bill.

When looking for new LED light bulbs, always check wattage (W), lumens (lm), temperature (K, C, or F, but also described as "Cool Daylight," "Cool White," "Warm White," and similar), energy class and similar.