Burning questions

How many watts does a light bulb use? Let’s shed light on it

Since childhood, we have been taught to turn off the lights when leaving the room. Only as adults with bills to pay we have realized it makes a difference in our pocket. How much electricity does a light bulb use? And how much does it cost you? Find out in this article.

4 types of light bulbs

The wattage of a bulb depends on the type. Before calculating energy consumption and costs, let’s figure out what kind of bulbs are in your home.

Incandescent bulbs

Historically, incandescent bulbs were the most common household lighting source. These bulbs work by passing an electric current through a tungsten filament, which heats up and produces light. Incandescent bulbs have warm color but are highly inefficient – they convert only about 5% of the energy into visible light. The rest is lost as heat.

Halogen bulbs

Halogens use 20-30% less energy compared to incandescents

Halogens are a type of incandescent bulb with a small amount of halogen gas within the bulb. Halogens are a more efficient version of incandescents and use 20-30% less energy, compared to them.

Compact fluorescent lamps

CFLs use 75% less energy compared to incandescents

FLs emerged as an energy-efficient alternative to incandescents. These bulbs use a gas-filled tube that produces ultraviolet light when stimulated by an electric current. The ultraviolet light then interacts with a fluorescent coating inside the tube, generating visible light. Fluorescents produce less heat and need about 75% less energy than incandescents of the same brightness.

Light emitting diodes

LEDs use 90% less energy compared to incandescents

LEDs represent the most energy-efficient lighting technology. These bulbs emit light when an electrical current passes through a microchip, illuminating the tiny light sources called LEDs. LEDs are incredibly efficient and use up to 90% less energy than incandescents.

Let’s sum up the most important figures about light bulb types in a small table:

Lumens (lm)230 - 375 lm
400 - 500 lm
700 - 900 lm
900 - 1125 lm1300 - 1500 lm
2W - 4W
5W - 7W
8W - 10W
9W - 13W
13W - 18W
Compact Fluorescent

Lumen (lm) — a unit of measurement that is used to quantify the amount of light emitted by a light source.

Calculating bulb consumption costs

Let’s translate your bulb’s consumption into real-world money. Check the wattage of your bulb usually printed on the base. That’s how much your bulb consumes per hour. Now divide the resulting number by 1000 to convert watts to kilowatts and multiply by the cost of 1kWh in your area. You can find it on your electricity bill.

Cost of use per hour = wattage / 1000 × price per 1kWh

Using a 60-watt incandescent bulb for an hour in California at a rate of $0.20 would cost a little over a cent. An LED bulb would cost even less – just two-tenths of a cent.

Four hours per day of incandescent bulb usage comes to 1.5kWh per week, 7kWh per month, and 90kWh per year. This translates to $0.30 daily, $1.4 and $18 if you live in California. Running a 10-watt LED bulb for four hours per day uses 0.3kWh of electricity per week, a bit over 1kWh per month, and 15kWh per year. Or $0.06 weekly, $0.2 monthly and $3 each year.

Now you can count how many light bulbs you have in your house and how much they cost you. Lights make up about 10% of your energy bill, according to the US Energy Information Administration.

5 bright tips to save money on light

Saving on light doesn’t mean living in the dark. With a few adjustments, you can do both – keep your home light and your energy costs low.

  • Switch to LEDs: LED lights are much more energy-efficient than traditional incandescent bulbs. They may cost a bit more upfront, but they last much longer and use a fraction of the energy.

  • Harness daylight: Natural light is not only free, but it also has health benefits. Open curtains and blinds during the day to brighten your space and avoid turning on electric lights.

  • Turn off unnecessary lights: It’s a simple yet effective tip. Develop the habit of turning off lights when you leave a room.

  • Invest in dimmers: Dimmer switches allow you to control the brightness of a light, which means you’re using less energy when you don’t need it.

  • Use motion sensors: Install motion sensors in areas like hallways, closets, and attics. These will automatically turn on the lights when you need them and turn them off when you don’t.

Powering your home with sunshine

Solar panels are a great way to power the lights. Even one 400W can sustain 15-30 LED bulbs when active. At night when there is no sun, you would have to rely on the battery though.

Vasilii Smirnov
Solar Installation Expert

One or two solar panels are great for a tiny DIY system in a shed or a garage where you just need the lighting. Light bulbs don’t need alternating current so sometimes a good controller can replace an inverter.

Read also:

Understanding energy efficient practices and using solar power leads to grand savings on electricity. Switch to LEDs, install solar panels, and read our article “How to make home energy efficient, save money and help the planet” for more energy-saving tips.

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Years of experience in translation and a love of nature help Julia find the right words to encourage going solar. She joined the team in 2023 and is happy to make her contribution to a greener future.

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