How Many Watts Does a Lamp Use? Calculate Light Consumption

  • Home Decor 101
  • Posted by: amy-golden
  • Jun 2, 2024

Since lighting is such an important element of daily life, knowing the many components of lamp wattage as well as amperage can help us make more economical and energy-efficient decisions. How many watts does a lamp use, how to keep the costs down, and other information regarding lamp wattage, amperage, and power consumption will all be made clear in this blog post.

Common Wattage Ranges for Different Types of Bulbs and Lamps

When attempting to comprehend how much power does a lamp use, wattage is a crucial measurement illustrating how quickly electrical energy is converted into light energy. The wattage of a lamp controls both its energy consumption and output of light.

Using differing quantities of electricity (measured in watts), different types of bulbs give varying levels of brightness (measured in lumens). To avoid damaging fixtures and maximize energy efficiency, it is essential to know how many watts does a lamp use when choosing bulbs.

The average lamp wattage of a lamp bulb can vary widely depending on the type of bulb and the intended use. The average power range of conventional incandescent bulbs is 40 watts for smaller bulbs and 150 watts for bigger ones. Nevertheless, average wattages have dropped dramatically as lighting alternatives have evolved to more energy-efficient models like light-emitting diodes (LEDs) and compact fluorescent lights (CFLs). Here is detailed data about the average lamp wattage of popular light bulbs, as well as how much does a lamp cost to run.

How many watts does a lamp use? (source: npr)
How many watts does a lamp use? (source: npr)
Types Wattage Monthly usage of each lightbulb in kWh* Yearly usage in kWh per bulb* Estimated yearly expenses** per lightbulb


25 3.00 36.00 $8.44
40 4.80 57.60 $13.50
60 7.20 86.40 $20.25
75 9.00 108.00 $25.32
100 12.00 144.00 $33.75
Compact Fluorescent Light (CFL)

Compact fluorescent light (cfl)

5 0.60 7.20 $1.69
8 0.96 11.52 $2.70
12 1.44 17.28 $4.05
15 1.80 21.60 $5.06
20 2.40 28.80 $6.75


2 0.24 2.88 $0.68
7 0.84 10.08 $2.36
10 1.20 14.40 $3.38
13 1.56 18.72 $4.39
18 2.16 25.92 $6.08


18 2.16 25.92 $6.08
28 3.36 40.32 $9.45
42 5.04 60.48 $14.18
53 6.36 76.32 $17.89
70 8.40 100.80 $23.63

*Estimated consumption based on a four-hour day, thirty-day workweek for your light.

**These annual estimates were calculated using the formula below, which used the average electricity cost in New York for May of 2024 and could be subject to changes.

Make sure the bulb's wattage does not exceed the maximum rating for your fixture for both energy efficiency and safety. For these features, more lumens per watt make LED lamps a better option for brightness, energy efficiency, and an ideal example for the question “How many watts does a lamp use?”

Average lamp wattage of led bulbs (source: eaton)
Average lamp wattage of led bulbs (source: eaton)

How much does it Cost to Run a Light Bulb?

A lamp or light bulb's operating costs are closely correlated with its wattage and the local cost of power. In order to determine the cost, two things you'll need to know include the wattage of the lightbulb and the cost of power per kilowatt-hour (kWh).

The following formula can be used to calculate how much does a lamp cost to run:

Cost = Wattage × Hours of Use × Cost per kWh / 1000

For instance, if you live in New York and your 7-watt LED light bulb is utilized for eight hours every day at an electricity cost of 23.44 cents per kWh, your daily expenses would be as follows:

Cost = 7 watts × 8 hours × 23.44c per kWh / 1000  ~ 1.3 cents per day

This equates to about $2.40 in electricity expenses per bulb during a year.

Approximately 9% of the energy used in a typical home is used for lighting. Data for the entire United States compiled by the EIA said that in 2021, a typical American home used 10,791 kilowatt hours (kWh) annually, or around 899 kWh per month. However, there are significant differences in the range of electricity usage.

How much does it cost to run a light bulb? (source: the engineering mindset)
How much does it cost to run a light bulb? (source: the engineering mindset)

Besides the type of bulb and the cost of electricity in the area, it is also important to consider other factors that can determine how much does a lamp cost to run, including: 

  • Domestic or commercial use: Depending on "the consumer class," providers usually charge varying prices for domestic, commercial, and industrial uses.
  • Frequency of usage: A significant component of your electric bill is the quantity of electricity you consume on a monthly basis, measured in kilowatt-hours, or kWh. You will pay more the more energy you consume.
  • Time of use: At different times of the day, you will pay different amounts for power. For example, using appliances overnight or during "off-peak" hours - which are usually overnight - results in lower costs. 

How to Estimate Your Light Bulb Energy Consumption?

To find out exactly how much electricity your lightbulb uses—or is supposed to use—you're generally better off looking at the estimated yearly electricity use in kWh. Multiply this amount by the typical local electricity rate to get an approximate annual cost of energy for your lightbulb. To determine the predicted monthly cost, divide the projected annual cost by twelve. 

How to estimate your light bulb energy consumption? (source: electric rate)
How to estimate your light bulb energy consumption? (source: electric rate)

When analyzing lamp power usage, amperage, also known as current, is a crucial component to take into account. That is why “how many amps does a lamp use” is another problem of great attention. Amperage is a unit of measurement for electrical charge flow that is directly correlated with voltage and wattage.

The following formula can be used for estimating amperage: 

Amperage (A) = Wattage (W) / Voltage (V)

To give an example, the amperage of a 75-watt incandescent lightbulb running on a 120-volt electrical system would be: 

Amperage = 75 watts / 120 volts = 0.625 amps

It's crucial to remember that most homes in the US have 120 volts of electricity, whereas many other countries across the world have 230 volts.

To determine how much power does a lamp use, you can use this calculation:

Energy Consumption (kWh) = Wattage × Hours of Use / 1000

Thus, the energy consumption of a 75-watt incandescent lightbulb used for four hours a day would be:

Energy Consumption = 75 watts × 4 hours / 1000 = 0.3 kWh per day

This may help you in figuring out how much does a lamp cost to run — a topic we'll cover in the next section. 

Factors Affecting Lamp Power Usage

Several factors can influence the power usage and energy consumption of a lamp or light bulb. You can optimize your lighting for energy efficiency and make well-informed choices by being mindful of these elements. They make sure of your answer for the question “how many watts does a lamp use”.

Bulb Type

Different bulb types affect energy use and cost. Amongst LEDs, CFLs, and incandescent bulbs with similar brightness but different efficiency, LEDs are the most energy-efficient alternative available, producing the same degree of brightness with a fraction of the wattage of the others. The type of bulb used influences not only how much energy is used, but also how long it lasts and how much it costs in the long run.

How does bulb type affect power usage? (source: eaton)
How does bulb type affect power usage? (source: eaton)

Here's a detailed comparison of common bulb types and how they impact power usage:

Types of Bulbs Power usage Efficiency Description
Incandescent Bulbs High Low Using only 10% of energy for light
Halogen Bulbs Moderate to High Slightly better than incandescent bulbs
  • Producing a lot of heat,
  • Using 20% less energy than incandescent bulbs
Compact Fluorescent Lamps (CFLs) Low to Moderate High
  • Consuming 70-80% less energy than incandescent bulbs 
  • Lasting 10 times longer
  • Containing mercury
LEDs Low Very high
  • Using 90% less energy than incandescent bulbs 
  • Having  longer lifespan 
  • Producing little heat 


Wattage directly correlates with power consumption and indicates how much power it consumes when it's turned on. The higher the wattage, the more electricity the lamp will use. So, how many watts does a lamp use? The average lamp wattage of an incandescent light bulb is 60 watts, while more energy-efficient light bulbs like LEDs or CFLs will have a lower wattage than an incandescent of the same kind. 

Wattage directly correlates with power consumption (source: research gate)
Wattage directly correlates with power consumption (source: research gate)

For instance, an LED may require only 8 watts of electricity, but a CFL may only require 14 watts. You can lower your lamp's electricity consumption by switching to a more energy-efficient light bulb with a lower wattage.

Brightness (Lumens)

The brightness, measured in lumens, and lamp power usage (wattage) are directly related to each other and are essential factors when considering energy efficiency and selecting the right lighting for your needs. This would also be one of the main points that determines how much power does a lamp use. 

The brightness (lumens) is essential factor when considering energy efficiency (source: rayming pcb & assembly)
The brightness (lumens) is essential factor when considering energy efficiency (source: rayming pcb & assembly)

For instance, due to its higher lumen count, a 20-watt LED street light substitute is more brilliant than a 100-watt halogen light. A 20-watt LED can bring about 3000–3400 lumens, while a 30-watt LED streetlight can be used in place of a typical 150-watt bulb that is only producing 4500–5100 lumens in the street. Even though the new 30-watt street LED light uses a lot less power, it will still emit the same amount of light. 

This provides you with an overview of the different lighting outputs: 

  • LED bulb: A 50-watt LED lights more than 7500 lumens.
  • CFL bulb: A 15-watt CFL emits more than 850 lumens.
  • Halogen bulb: A 45-watt Halogen bulb emits more than 750 lumens.
  • Incandescent bulb: A 60-watt incandescent emits more than 700 lumens.

Usage Hours

Increasing the usage hours increases the total power consumption. For instance:

If the 60-watt incandescent lamp is used for 240 hours instead of 120 hours in a month, the energy usage would double: 0.06 kW×240 hours=14.4 kWh.

Similarly, if the 10-watt LED lamp is used for 300 hours instead of 150 hours, the energy usage also doubles: 0.01 kW×300 hours = 3 kWh.

Increasing the usage hours increases the total power consumption (source: learnbnb)
Increasing the usage hours increases the total power consumption (source: learnbnb)

Higher energy consumption is the result of longer usage times. However, energy-efficient lamps (like LEDs) consume less power than incandescent or fluorescent lamps for the same amount of light output. For examples: 

  • In comparison to incandescent light bulbs, which require 60 watts of electricity on average, LED light bulbs only need about 10 watts. 
  • The monthly electricity consumption of an incandescent light bulb used for two hours a day is around 12.2 kWh, and the annual electricity consumption is 43.8 kWh.
  • About 0.61 kilowatt-hours of electricity are used per month, and 7.3 kilowatt-hours are used annually when an LED light bulb is used for two hours a day.


Among the several elements that affect lamp life, voltage is a key factor as the power decreases with decreasing voltage, which prolongs the life of an incandescent light bulb; also, the light efficiency, measured in lumens per watt, decreases. 

Conversely, voltage increases result in higher watts, brighter light or more lumens produced, higher lumens per watt energy conversion, and shorter lamp life. There are trade-offs between efficiency and lamp life when designing an incandescent light bulb.

The power consumption increases with increasing voltage (source: research gate)
The power consumption increases with increasing voltage (source: research gate)

When the voltage is increased, the power consumption of devices with a fixed resistance, such as incandescent bulbs, increases quadratically. For instance, doubling the voltage and maintaining a constant resistance in a bulb results in a four-fold increase in power consumption. 

Many modern lamps have built-in drivers that regulate power usage to maintain a consistent power consumption across average lamp wattage and a range of voltages. These drivers adjust the current to ensure the lamp uses the same power even if the voltage changes within a specified range. For example, an LED lamp rated at 10 watts may operate within a voltage range of 100-240 volts. The driver adjusts the current so that the lamp always consumes around 10 watts.

Ambient Temperature

Extreme temperatures can affect the efficiency and lifespan of lamps, particularly LED lamps. Here’s a detailed look at how temperature impacts lamp power usage:

Types of bulb Impact of Temperature Optimal Temperature Range
  • The changes in ambient temperature have a relatively minor effect in energy-efficiency.
  • Stable power consumption when ambient temperature changes.
-20°C to 40°C (-4°F to 104°F)
  • Ambient temperatures can affect efficiency. 
  • Increased power usage and reduced light output in cold environments.
15 to 25°C (59°F to 77°F)
  • Can operate at higher pressures and temperatures.
  • Moderate changes in ambient temperature have minimal impact on power usage.
0°C to 35°C (32°F to 95°F)
LEDs Increased power consumption due to high ambient temperatures might result in decreased efficiency and a shorter lifespan.  -20°C to 30°C (-4°F to 86°F)

Comparing Lamp Wattage and Amperage

The connection between wattage and amperage is crucial to comprehend when comparing the wattage and amperage of various lamps or light bulbs.

As was previously mentioned, we have the formula to determine amperage: 

Amperage (A) = Wattage (W) / Voltage (V)

In detail, voltages, amps, watts and kilowatt-hours are defined as:

Volts (V) is identified as the unit of measurement for voltage, or the rate at which electricity moves through a circuit or device.

Amps (A) also known as amperes, are units of measurement for the quantity of electrons passing through a circuit which is known as electric current.

Watts (W) is calculated by multiplying amps by volts and considered as the unit of measurement for energy consumption.

Kilowatt-hours (kWh) is the unit of measurement for energy use over time that is normally used to calculate electricity bill. 

Tips for Reducing Lamp Energy Consumption

Take into account the following advice to effectively reduce energy consumption and the cost of running your lamps while still maintaining adequate lighting for your needs:

  • Switch to LED bulbs or other energy-efficient bulbs: LED bulbs use significantly 75% less energy than traditional incandescent bulbs and last much longer. Although they might have a slightly higher upfront cost, they'll save you money in the long run due to their energy efficiency and durability. 
  • Use smart lighting and dimmers: Smart lighting systems or dimmer modes allow you to control your lamps remotely through a smartphone app or voice commands. They often come with features like scheduling, dimming, and motion sensing, which can help optimize energy usage and reduce costs by ensuring lights are only on when needed.
  • Install motion sensors: Motion sensors can automatically turn lights on and off based on movement in a room. This prevents lights from being left on when no one is present and can significantly reduce energy waste.
  • Implement timers or schedules: Set timers or schedules for your lamps to turn on and off at specific times of the day. This can help ensure lights are only on when needed and avoid unnecessary energy consumption during times when no one is using the space.
  • Optimize lamp placement and natural lighting: Position lamps strategically to make the most of natural light during the day, reducing the need for artificial lighting. Additionally, using lighter paint colors on walls and ceilings can help reflect light and brighten a room without the need for additional lamps.
  • Regular maintenance: Keep lamps and light fixtures clean and free of dust to ensure they operate efficiently. Dust buildup can reduce light output and force lamps to consume more energy to produce the same amount of light.
  • And so many other tips and practices into your daily routine. 


In conclusion, it is essential to comprehend how many watts does a lamp use as well as other specifications like amperage and average lamp wattage, in order to maximize energy efficiency and make well-informed lighting choices. Keep in mind that, over time, switching to more energy-efficient lighting solutions like LEDs and CFLs can not only result in significant cost and energy savings but also lessen the influence on the environment.


What Is the Average Light Bulb Energy Consumption?

Depending on the type of bulb, the average energy consumption of light bulbs might vary significantly. This is a broad summary:

  • Incandescent bulbs: 25-100 watts
  • Compact fluorescent (CFL) bulbs: 9-26 watts
  • LED bulbs: 3-20 watts

The most energy-efficient bulbs are LEDs, which usually consume 75% less electricity than conventional incandescent bulbs.

How Much Electricity Does a Light Bulb Use a Day?

The amount of electricity a lightbulb needs each day depends on its wattage and how many hours it is used. The following formula can be used to determine the daily energy consumption: 

Energy Consumption (kWh) = Wattage × Hours of Use / 1000

How Can I Cut the Cost of Running a Light Bulb?

The following suggestions may help in reducing the price of illuminating a lightbulb:  

  1. Convert to energy-efficient lighting: LED or CFL bulbs require a lot less electricity than incandescent bulbs.
  2. Install dimmers: Use dimmers to cut down on energy and wattage usage when lower light levels are appropriate.
  3. Switch off the lights: Make sure that all lights are off while not in use, particularly in empty rooms or spaces.
  4. Use natural lighting: Make the most of natural lighting by placing lamps next to windows and only turning them on when absolutely required.
  5. Regularly maintain lighting: To get the most out of your lamps and light fixtures in terms of efficiency and light production, keep them clean and in good condition.



I work as a freelance blogger in Seattle, Washington. I've been freelancing full-time for 5 years. I'm interested in anime, resin art, and mechanical keyboards.


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