How Much Does It Cost to Run a Light Bulb for 24 Hours?

Accurately estimating energy costs is crucial in managing household expenses and making informed choices about energy consumption. In this article, we will delve into the cost of running a light bulb continuously for 24 hours. By exploring different factors that influence the cost, you will gain comprehensive insight into the financial impact of lighting choices.

Light Bulb Types

Light bulbs come in various types, including incandescent, CFL (Compact Fluorescent Lamp), and LED (Light Emitting Diode). Each type differs in energy efficiency and wattage. The energy efficiency of a light bulb refers to how effectively it converts electricity into light. Wattage represents the power consumption of a bulb, which directly influences its energy usage and cost.

Calculating Wattage

Wattage is a measurement of the power consumed by a light bulb. To find the wattage of a bulb, you can refer to the label or packaging. For example, an incandescent bulb may have a wattage of 60W, while a CFL bulb might have a wattage of 15W. 

Determining Electricity Cost

The cost of electricity is typically measured in kilowatt-hours (kWh). Your utility provider determines the electricity rate, which varies depending on your location and provider. Calculating the cost of electricity for running a light bulb, will provide you with adequate insights into the financial implications of your lighting choices.

Incandescent Light Bulbs

Incandescent bulbs are known for their energy inefficiency, as they produce more heat than light. Let’s take a closer look at the cost of running an incandescent bulb for 24 hours. For example, if the electricity cost is $0.15 per kWh and the wattage of the incandescent bulb is 60W, the cost of running it continuously for 24 hours would amount to $0.216 (0.15 * (60/1000) * 24).

Comparing this cost with more energy-efficient options will highlight the potential for significant savings by choosing alternative bulbs.

Compact Fluorescent Lamps (CFLs)

CFL bulbs offer improved energy efficiency compared to incandescent bulbs, making them a more environmentally friendly option. Let’s calculate the cost of running a CFL bulb for 24 hours, assuming a wattage of 15W and the same electricity rate as before. The cost of running a CFL bulb continuously for 24 hours would be $0.054 (0.15 * (15/1000) * 24).

In addition to their energy efficiency, CFL bulbs also have a longer lifespan compared to incandescent bulbs, contributing to further cost savings.

Light Emitting Diodes (LEDs)

LED bulbs stand out as the most energy-efficient lighting option available. Despite their higher upfront cost, their long lifespan and minimal energy consumption make them a cost-effective choice in the long run. Let’s calculate the cost of running an LED bulb for 24 hours, assuming a wattage of 8W, using the same electricity rate. The cost of running an LED bulb continuously for 24 hours would amount to $0.0288 (0.15 * (8/1000) * 24).

The longevity of LED bulbs combined with their energy efficiency makes them a worthwhile investment for both cost savings and environmental sustainability.

Factors Affecting Cost

Apart from the type of bulb used, there are other factors that can influence electricity costs. These include the number of light bulbs in use, the duration of usage, and any additional energy-saving features incorporated into the lighting system. To further reduce energy consumption and save on lighting bills, consider implementing the following tips:

  • Utilize natural daylight whenever possible.
  • Install motion sensor switches to automatically turn off lights in unoccupied rooms.
  • Opt for dimmer switches to adjust lighting intensity according to your needs.
  • Regularly clean light fixtures and replace old bulbs to ensure optimal efficiency.

Practical Examples

To narrow down the cost and energy efficiency differences between various bulb types, let’s examine real-world scenarios and perform calculations. By comparing the costs of running different bulbs for 24 hours, you can make an informed decision that aligns with your budget and sustainability goals.

  • Scenario 1: Incandescent bulb: Wattage – 60W, electricity cost – $0.15/kWh
  • Scenario 2: CFL bulb: Wattage – 15W, electricity cost – $0.15/kWh
  • Scenario 3: LED bulb: Wattage – 8W, electricity cost – $0.15/kWh

By calculating the costs of running each bulb type for 24 hours based on the given wattage and electricity cost, you can clearly see the potential savings associated with energy-efficient bulbs.


Understanding the cost of running a light bulb for 24 hours is essential in managing energy expenses and making environmentally conscious choices. By opting for energy-efficient bulbs such as CFLs or LEDs, you can significantly reduce electricity costs over time while contributing to a greener future. Remember to consider factors like wattage, electricity rates, and additional energy-saving measures when evaluating your lighting choices.