How Much Does it Cost to Leave a Light On for 24 Hours?

how much does it cost to leave a fluorescent light on

When you start thinking about reducing your energy usage and shaving off a few dollars of your electricity bill, you usually worry about things like the dishwasher, washing machine, or heating. One item you probably don’t think twice about is your light bulbs. Why? They are small, so they can’t consume that much electricity, even if you leave them on all day right? Well, let’s explore if that’s the case.

How Much Energy Does a Light Bulb Use?

Do light bulbs use a lot of electricity? While individual bulbs consume small amounts of electricity (around 40 watts), the tricky part is that you probably have a lot of them in the house, so the costs quickly add up. Just think about every room of your house and count the number of bulbs you have – it can easily be up to twenty or thirty!

Each light bulb you buy will have its wattage displayed on the box so you can quickly tell how much energy will it consume. For example, if you keep a 60-watt incandescent bulb on for an hour, it will burn, well 60 watts. However, that does not mean that it will give you the same amount of light, as another 60-watt bulb.

Different Bulbs Use Different Amounts of Energy

There are generally three types of light bulbs:

Incandescent bulbs – This old-fashioned, 100-years old technology emits light by heating the filament inside the bulb. Because of the low efficiency, these bulbs are being phased out at speed. In 2010, they were installed in 68% of U.S. homes but by 2016, this number dropped to 6%. 

Compact fluorescent light bulbs (or CFLs) – This bulb is largely perceived as a replacement for incandescent or halogen lamps and is mainly available in two forms – screw-in and plug-in. They are four times more efficient and last up to 10 times longer than incandescents (a 22 watts CFL will give you as much light as a 100-watt incandescent).

Light-emitting diodes (LEDs) – Crown jewels among the light bulbs. This technology is relatively new on the market, incredibly 90% more efficient, and lasts 25 times longer than incandescent bulbs; and the bulbs are so thin that they can be designed in any way imaginable. Despite its widely-acknowledged benefits, some people worry that LEDs might have adverse health effects, mainly due to emitting blue lighting.

how much does it cost to leave a 60 watt light bulb on for 24 hours

To make a comparison between these types of bulbs easier, we will use lumens. Lumens measure how much light you are getting from a bulb. More lumens means it’s a brighter light; fewer lumens means it’s a dimmer light.

The 60 watts incandescent light bulb we mentioned before will produce approximately 800 lumens. However, a LED bulb will only need approximately 11 watts to produce the same amount of lighting, therefore saving your electricity.

Use this handy table to guide you next time you go shopping for light bulbs!

Incandescent Bulb WattageEquivalent Halogen Bulb WattageEquivalent CFL Bulb WattageEquivalent LED Bulb Wattage
40 W (~460 lm)28 W7 W6 W
60 W (~830 lm)45 W13 W11 W
75 W (~1100 lm)56 W18 W15 W
100 W (~1800 lm)80 W28 W24 W

Determining Wattage and Usage

Coming back to our initial question – will lights burn a lot of electricity if we leave them on? Let’s work with the assumption that you have thirty 60 watts incandescent lightbulbs. If you live in Texas and you haven’t yet switched energy suppliers, you are probably paying the standard energy tariff of 12 cents per kilowatt-hour. Leaving the lights on the whole day will therefore cost you:

30 bulbs x 0.06 (60 watts / 1000) kilowatts x 24 hours x 12 cents = $5.2 a day.

Not the end of the world, but these costs can add up relatively quickly.

Energy Inefficiency Due to Heat Loss

Another downside of incandescent bulbs is the heat loss – nearly 90% of energy is wasted as produced heat and only about 5% is turned into visible light. That puts this type of bulb at a high risk of overheating and becoming a fire hazard. You probably know it – when you are changing an incandescent bulb, you always have to wait a few minutes because you would burn your fingers. 

LEDs produce almost no heat when they are burning and are kept cool even during prolonged periods of being on. In addition, LEDs operate on low-voltage electrical systems, as well as in cold temperatures, don’t contain any mercury, or emit UV or infrared radiation.

How Can You Save Money on Light Bulbs?

Next time you are due to replace your lights, you should opt for LED bulbs instead of CFLs or incandescents. If you currently have 30 bulbs at home, you can save up to $200 in a year if you upgrade all bulbs to LEDs. In addition, the average life expectancy of an LED lightbulb is 50000 hours. That means that if you use it for 10h a day, it should last you 14 years. You are more likely to change your house before you need to change the light bulb.

You can also switch electricity suppliers to pay less for the energy used by your lights. If you live in Texas and you haven’t yet switched, you are probably paying around 11.85 cents per kWh. However, a quick look at offers from other providers returns several long term contracts with an average rate of approximately 5.99 cents, reducing your energy bill even lower.


How Much Does it Cost to Leave A 60-watt Light Bulb On for 24 Hours?

Calculating the energy usage of a light bulb is relatively straightforward and will only take you a few minutes. Let’s say you have a 60-watt incandescent lightbulb and you are paying 12 cents per kWh of energy. Leaving the bulb on the whole day will therefore cost you:

0.06 (60 watts / 1000) kilowatts x 24 hours x 12 cents = approximately 20 cents in one day.

Does Leaving the Lights On Cost a Lot Of Money?

Individual light bulbs won’t use a lot of energy, but the costs can quickly add up. Just consider that an average U.S. household has 45 light bulbs, so if you forget to turn them off before you leave on holiday, you might be coming home to a steep bill. You can reduce the energy consumed by investing in LEDs (light-emitting diodes) which are approximately 90% more efficient than incandescent lights.

Is it Ok to Leave a Light On All Night?

Leaving one light bulb on during the night will probably not make a dent in your wallet, but you shouldn’t get into the habit of leaving lights on at all times. Given that an average U.S. household has 45 bulbs, leaving them on all night can cost you approximately $2.5 (45 incandescent bulbs x 0.06 kilowatts x 7H x 12 cents). Over the course of a month, this can quickly add up.

We hope that this article gave you some food for thought for the next time you will be shopping for new lights. Although the energy cost of leaving one bulb on for the day isn’t high, these costs can quickly add up. Investing in LEDs, which are not only 90% efficient, but also last longer will pay for itself in the long run – a bonus is that the design possibilities for LED lights are endless.

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