Home generalWatt conversion: light bulb - energy saving lamp - LED

Watt conversion: light bulb - energy saving lamp - LED

  • Check wattage
  • Convert lumen number
  • color temperature
  • environmental properties
  • durability
  • costs
    • 1) LED
    • 2) Energy-saving lamps

LEDs and energy-saving lamps consume significantly less power than conventional light bulbs. But this savings opportunity is a new challenge when buying. Since the original Watt figure has lost importance, the question arises, how to find the right models. In our guide you will find instructions for the selection of LEDs and energy saving lamps. In a conversion table, you can see which purchase you need to make to get an approximately equal brightness.

Energy-saving lamps and LEDs make it possible to save around 80 percent of electricity costs. The bulbs operate with a completely different construction, whereby the old selection criteria are no longer valid by means of performance. Decisive is above all the brightness, which is indicated in lumens. However, there are further differences between the different light sources, for example the color temperature . It decides how well we feel about the light and how the light was perceived. Therefore, this information must be considered when buying. This new information gives you the opportunity to select the lighting in even greater detail and to personalize it. In many countries, including Germany, most of the classic light bulbs are already banned because they consume too much energy.

Energy saving lamp, LEDs, light bulb

The selection criteria have changed

In the past, the choice of bulbs was primarily on the wattage. It could be seen as an indication of the brightness and allowed a good classification of the light bulbs. On modern packaging of LEDs and energy-saving bulbs, various indications are highlighted, such as wattage, lumen count and color temperature. LEDs and energy-saving lamps consume significantly less watt (W) compared to conventional light bulbs, reducing energy costs. Therefore, it is a logical consequence that a neutral and independent of the statement in W size had to be introduced. This task has taken the brightness (lumens). However, an approximate conversion of the W can be made from the brightness. The table shown in step 1 is created by first assigning the corresponding lumen information to the W numbers of the bulbs and then selecting a suitable energy-saving lamp or a "power-equivalent" LED (based on brightness).

Check wattage

On the wattage, you can estimate how bright the light bulb is. However, this is only a rough guideline, the fine-tuning in the selection also depends on the color temperature and the number of lumens. The following table shows the wattage of LEDs and energy-saving bulbs that matches the performance of a classic light bulb:

1 of 2
light bulb
halogen lamp

Conversion Chart: LED (Energy Saving Lamp / Light Bulb)

LEDEnergy saving lamp / light bulb
2-3 W3 to 4 W / 15 W
4-5 W6W / 25W
6-8 W9 to 10 W / 40 W
9-12 W13 to 14 W / 60 W
13-14 W17 W / 75 W
18-19 W21 to 22 W / 100 W

Thus, the power consumption of energy-saving lamps or LEDs is only about 1/5 as large as the associated light bulbs. This in turn offers you a savings potential of around 20 percent. The classic 100 watt bulb consumes only 18 to 19 watts in the modern LED version. An approximately equal brightness produces a 21 to 22 Watt energy saving lamp. As a rule of thumb, when converting the wattage from light bulb to LED and energy saving lamp:

Wattage of the LEDs / Energy saving lamps = Wattage of the bulb / 5

In the case of the LEDs, the actual value is slightly lower, for the energy-saving lamps, the value is slightly higher.

Example of the rule of thumb: 100 W / 5 = 20 W

Thus, a classic light bulb can be replaced by a modern 20 W bulb. LEDs have an actual conversion value of 18 to 19, which is therefore slightly lower than 20 W. Energy-saving lamps are 21 to 22 W about 10 percent above the value calculated by the rule of thumb.

Example calculation 1: light bulb, LED and energy saving lamp

Let's say you've screwed in a 100 W lightbulb in your living room. Then you can replace them with a 18 to 19 W LED bulb or a 22 Watt energy saving bulb. If the electricity costs 0.25 euros per kilowatt hour, then the energy costs are calculated as follows:

Time: 1 hour burning time

  • Electricity costs for the old pear: 0.25 euros x 100/1000 = 0.025 euros = 2.5 cents
  • Power costs for the LED: 0.25 x 19/1000 = 0.005 Euro = 0.5 cents
  • Energy costs for the energy saving lamp: 0.25 x 22/1000 = 0.0055 Euro = 0.55 cents

By replacing the light bulbs they save about 80 percent of energy costs.

Convert lumen number

Strictly speaking, the wattage is not the decisive factor for the brightness but the number of lumens. Therefore, it is important to consider the value of lumens when switching from light bulbs to LEDs or energy saving bulbs. The following conversion table shows the lumen values ​​of the classic bulbs:

conversion table

25 W equals 230 lumens
40 W equals 430 lumens
60 W corresponds to 730 lumens
60 W corresponds to 730 lumens

If you would like to convert the above-mentioned 100-watt bulb, then you must select a bulb that delivers at least 1, 380 lumens of brightness. Replacing the light bulbs according to the conversion table from step 1, one finds that most of the LEDs offered by the manufacturers in the market have more lumens than the corresponding light bulbs. The energy-saving lamps, however, have a little less lumens than the associated incandescent lamps. This is because only natural numbers occur as values ​​and thus a 100 percent conversion is not possible.


A 100 watt bulb has around 1380 lumens, and a 22 watt energy saving bulb has 1371 lumens.

Conversely, this means that you must pay particular attention to the lumen specifications and the wattage of LEDs in case of doubt may also be slightly lower than in the table from step 1.

color temperature

Another selection criterion when replacing the light bulb is the color temperature. The conventional bulbs had a constant color temperature. The 60-watt bulb had a color temperature of 2, 700 Kelvin. The same wattages may have different Kelvin values. The individual color values ​​are divided into warm white, neutral white and daylight white.

Tip: If you want to achieve a similar effect as the classic light bulbs, you should opt for warm white variant.

Roughly, the different bulbs can be sorted into three different areas:

Warm white, neutral white, daylight white
Warm white: 2, 500 to 3, 000 Kelvin
Neutral white: 3, 500 to 4, 000 Kelvin
Daylight white: 4, 000 to 7, 000 Kelvin

Tip: Note that not all LEDs are dimmable. If you want to use this function, then you must pay attention to the appropriate marking.

When is which color temperature most suitable "> Environmental properties

LEDs and energy-saving lamps consume less power and, from this point of view, have positive environmental properties. However, mercury is inside the energy-saving lamps, which is harmful to the environment and highly toxic. If the energy-saving bulbs fall or leak, then there is a high risk to health. It is important that the resulting vapors are not inhaled and that sufficient ventilation is provided immediately. LEDs are non-hazardous and contain no mercury.

Tip: If an energy-saving lamp falls down, you must immediately open the window and then leave the room. Close the door and wait around 30 to 60 minutes. During this period, the toxic fumes rise and for the most part leave the room through the window. Now you have to remove all splinters thoroughly and then wipe them again. You have to throw away the rag because it may still contain mercury.


With LEDs and energy saving lamps you can save a lot on electricity costs. In a comparison, the durability is a crucial factor. The following presentation provides an overview of the possible illumination times:

  • Classic light bulb about 1, 000 hours
  • LEDs maximum 44, 000 hours
  • Energy-saving lamps maximum 18, 000 to 20, 000 hours

However, the actual lifetimes differ greatly among the different manufacturers. On the packaging you will generally also find an indication of the possible times of use. It is striking that the classic light bulbs have the shortest lifetimes. The distance is even very clear. On the other hand, however, there are also higher investment costs.


Based on an average price of 10 euros for the energy-saving lamps and the LEDs, then you can calculate when the purchase has paid off.

1) LED

LED reflector

Assuming the LEDs are used for 40, 000 hours. Then you have saved 80 percent of the electricity costs during this time.

40, 000 hours at a power of 20W (former 100W bulbs)
40, 000 hx 20 W = 800, 000 Wh = 800 kWh

If one puts the electricity costs with 0.25 euro per kWh, then costs arise in the amount of
800 x 0.25 Euro = 200 Euro

A conventional light bulb would have at the same time
40, 000 hx 100 watts = 4, 000, 000 Wh = 4, 000 kWh consumed.

This would cost in the amount of
4, 000 x 0.25 = 1, 000 euros

This is worth the investment for the LEDs.

2) Energy-saving lamps

Energy saving lamp

Energy-saving lamps burn around 18, 000 hours. Also in this time high costs are saved, so that in this case the purchase is worthwhile. If one uses the life with 20, 000 hours, then around 400 euros per bulb can be saved.

Tips for quick readers:

  • Convert is done via lumens and color temperature
  • Convert using a conversion table
  • decisive for conversion is lumen
  • Kelvin represents the color temperature
  • 2, 700 Kelvin: homely
  • 4, 000 to 7, 000 Kelvin: daylight white
  • Energy-saving lamps contain mercury
  • Mercury is highly toxic
  • Conversion to LEDs and energy-saving lamps: 80 percent savings
  • Rule of thumb for converting: W of light bulbs / 5
  • LEDs / energy-saving lamps have a longer service life
  • Cost of modern bulbs: around 10 euros
  • Cost of bulbs: around € 0.50
  • higher investment costs pay off due to their long service life
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