steradian or solid angle

Lumens to Candela Calculator And How To Use It?

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Hey, do you know what lumens and candela are? They are both units of measurement for light, but they are not the same thing. In fact, they can tell you a lot about the quality and performance of a light source, such as a light bulb or a flashlight. Knowing the difference between them can help you choose the right light source for your needs, whether you need it for indoor or outdoor activities, for close-range or long-distance illumination, or for general or specific tasks.

In this article, I will explain to you what lumens and candela mean, how they differ, and how to convert lumens to candela and vice versa. I will also give you some tips and tricks for choosing the right light source based on lumen and candela, as well as answer some frequently asked questions about them. By the end of this article, you will have a better understanding of these two important concepts and how to use them to your advantage. Let’s get started!

Lumen to Candela or Candlepower Calculator

Lumen to Candela or Candlepower Converter

Enter the luminous flux in lumens and either the apex angle in degrees or the solid angle in steradians and press the Calculate button to get the luminous intensity in candela or candlepower:










If you need to convert Candelas to Lumens, you can check here!

How to Use a Lumen to Candela Calculator

If you don’t want to do the math yourself, you can use our lumen to candela calculator above or our candela to lumen calculator online.

You can also use this tool to convert lumen to candlepower, which is another way of saying candela. Just remember that one candlepower is equal to one candela. But if you want to do the math yourself, we got you covered below. Now let’s get started then!

What are Lumens?

Lumens (lm) measure the total amount of light output by a source, like a light bulb or a flashlight. The more lumens a light source has, the brighter it is. For example, a 9-watt LED bulb has about 800 lumens, while a 12-watt LED bulb has about 1100 lumens. You can read our watts to lumens conversion post as well to learn more.

Lumens are useful for comparing the overall brightness of different light sources. However, they do not tell you how the light is distributed or focused. For that, you need to look at another unit of measurement: candela.

What are Candelas?

Candela (cd) measures how much of the light output by a source is traveling in a particular direction. It is also called candlepower or intensity. The more candela a light source has, the more focused and narrow its beam is. For example, a flashlight with 1000 lumens can have different candela values depending on how wide or narrow its beam is. A wider beam will have a lower candela value, while a narrower beam will have a higher candela value.

Candela is useful for comparing the directionality and concentration of different light sources. However, they do not tell you how much light is actually reaching a surface or an object.

How to Convert Lumens to Candela and Vice Versa

As you can see, lumens and candela are both related to each other, but they measure different aspects of light. To convert lumens to candela or candela to lumens, you need to know one more thing: the angle of the beam/apex.

The angle of the beam/apex is measured in degrees or steradians (a unit of solid angle). The smaller the angle, the more concentrated the light is.

Steradian Solid Angle Explanation
Steradian/Solid Angle Explanation

To convert lumens to candela, you need to divide the lumens by the solid angle in steradians. To convert candela to lumens, you need to multiply the candela by the solid angle in steradians. Here is an example:

Let’s say you have a flashlight with 1000 lumens and a beam angle(apex angle) of 10 degrees. To find the solid angle in steradians, you need to use this formula:

The formula to calculate candela is:

Φv(lm) = Iv(cd) × Ω(sr)

where Iv is the luminous intensity in candela, Φv is the luminous flux in lumens, and Ω is the solid angle in steradians.

solid angle = 2π(1 – cos(beam angle / 2))

Ω(sr) = 2π(1 – cos(θ/2))

Then you’ll get 41824.52 candelas!

As you can see, the same flashlight can have different lumens and candela values depending on how wide or narrow its beam is. That’s why it’s important to know both when choosing a lighting device for your needs.

FAQ about Lumens and Candela

Here are some frequently asked questions about lumens and candela that might help you understand them better:

What is the difference between lumen and candela?

Lumen measures the total amount of light output by a source in all directions, while candela measures the amount of light output by a source in a particular direction.

candela vs lumens
Candelas and Lumens Explanation

How do I convert lumen to candela?

To convert the lumen to candela, you need to divide the lumen by the solid angle in steradians.

How do I convert candela to lumen?

To convert candela to lumen, you need to multiply the candela by the solid angle in steradians.

What is the relationship between lumen and candela?

The relationship between lumen and candela is given by this formula: lumen = candela x solid angle.

How do I find the solid angle in steradians?

To find the solid angle in steradians, you need to use this formula:

Ω(sr) = 2π(1 – cos(θ/2))

The solid angle Ω in steradians (sr) is equal to 2 times pi times 1 minus cosine of half the cone apex angle θ in degrees (°).

What is a good lumen-to-candela ratio for a flashlight?

There is no definitive answer to this question, as it depends on your personal preference and needs. However, a general rule of thumb is that a higher lumen-to-candela ratio means a wider and brighter beam, while a lower lumen-to-candela ratio means a narrower and more focused beam.

Is 1 Candela equal to 1 Lumen?

No, 1 candela is not equal to 1 lumen. The relationship between lumens and candela is: 1 lumen = 1 candela multiplied by the solid angle of the light beam. The solid angle is a three-dimensional measurement of how much of the light is visible from a particular point. It is measured in units of steradians (sr). Therefore, the same candela value can have different lumen values depending on the solid angle of the light beam.

Is Candela more important than Lumens?

Candela and lumens are both important, but they measure different aspects of light. Candela measures the intensity of light in a specific direction, while lumens measure the total amount of light output by a source in all directions. Depending on your purpose and environment, you might need to consider one more than the other. 

For example, if you need a light source that can project a strong focused beam over a long distance, you might want to look at the candela value more than the lumens value. On the other hand, if you need a light source that can illuminate a large area with a wide and bright beam, you might want to look at the lumens value more than the candela value.

What is a good candela rating?

There is no definitive answer to this question, as it depends on your personal preference and needs. However, a general rule of thumb is that a higher candela rating means a more focused and narrow beam, while a lower candela rating means a wider and softer beam. 

A good candela rating for a flashlight can range from 1000 to 50000 cd or more, depending on how far and how wide you want to see. A good candela rating for a lamp can range from 10 to 1000 cd or more, depending on how soft and comfortable you want the light to be.

Why is Candela important?

Candela is important because it tells you how much of the light output by a source is traveling in a particular direction. This can help you determine how far and how wide you can see with a light source, as well as how focused and concentrated the light is. Candela can also help you compare the directionality and concentration of different light sources based on their beam shape and angle.

Is high Candela good?

High candela can be good or bad depending on your needs and preferences. High candela means that the light source has a high intensity of light in a specific direction, which can be useful for activities that require long-distance illumination or spotting objects far away.

However, high candela can also mean that the light source has a narrow and sharp beam, which can be uncomfortable or blinding for close-range activities or general lighting purposes. Therefore, high candela is not always good or bad but rather depends on what you need it for.

What are some examples of candela and lumen values for common light sources?

Here are some examples of candela and lumen values for common light sources:

Light sourceCandelaLumenBeam angle
Candle112.57360°
Flashlight10084.1860°
LED bulb500420.8960°
Car headlight1500321.1430°
Laser pointer50000.00000120.001°

Tips and Tricks for Choosing the Right Light Source Based on Lumen and Candela

Here are some tips and tricks for choosing the right light source based on lumen and candela:

  • Consider your purpose and environment.

    Different situations require different types of light sources. For example, if you need a light source for outdoor activities like hiking or camping, you might want a flashlight with high lumens and high candela, so you can see far and wide. On the other hand, if you need a light source for indoor activities like reading or working, you might want a lamp with low lumens and low candela, so you can have a soft and comfortable light.
  • Compare similar products.

    When comparing different light sources, make sure you are comparing apples to apples. For example, if you are comparing two flashlights, make sure they have the same battery type, size, weight, and features. Otherwise, you might end up with a biased or inaccurate comparison.
  • Read reviews and feedback.

    Sometimes, the best way to choose a light source is to learn from other people’s experiences. You can read reviews and feedback from online platforms like Amazon or YouTube, or ask your friends or family for recommendations. This way, you can get an idea of how the light source performs in real life, and what are its pros and cons.
  • Test it yourself.

    Finally, nothing beats testing the light source yourself. If possible, try to get a hands-on experience with the light source before buying it. You can visit a local store or borrow from someone who has it. This way, you can see for yourself how the light source works, how bright it is, how focused it is, and how it suits your needs.

TL;DR / Conclusion


We hope this article has helped you understand the difference between lumens and candela, and how to convert lumens to candela and vice versa. Here are some key points to remember:

  • Lumens measure the total amount of light output by a source in all directions.
  • Candela measures the amount of light output by a source in a particular direction.
  • To convert lumens to candela, you need to divide the lumens by the solid angle in steradians.
  • To convert candela to lumens, you need to multiply the candela by the solid angle in steradians.
  • You can use our lumen to candela calculator to do the conversion for you.
  • You can also convert lumen to candlepower, which is another way of saying candela.
  • You should consider your purpose and environment when choosing a light source based on lumen and candela.
  • You should compare similar products when comparing different light sources based on lumen and candela.
  • You should read reviews and feedback from other users when choosing a light source based on lumen and candela.
  • You should test the light source yourself if possible when choosing a light source based on lumen and candela.

Here is a poem that makes Lumen and Candela’s relationship more memorable:

Lumen and candela are both measures of light
But they are not the same in every sight
Lumen tells you how much light is there
Candela tells you how much light is where

Lumen is the total output of a source
Candela is the intensity of a course
Lumen is the brightness of a beam
Candela is the focus of a stream

Lumen and candela are related by an angle
The smaller the angle, the more they mingle
To convert them, you need to know the solid angle in steradians
Then you can divide or multiply them by this radians

Lumen and candela can help you choose a light source
Depending on your purpose and your resource
Lumen and candela can make a difference in your vision
So learn them well and make a wise decision

Batu

Thank you for reading. If you have any questions or comments, please leave them below. I would love to hear from you. And don’t forget to share this post with your friends who might be interested in lighting. Don’t forget to check our posts about smart lighting, see you next time, and happy lighting!

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Philosophy: We want to make sure that our readers can use smart home products with maximum efficiency. Our ultimate desire in this blog is to ensure our readers use smart home gadgets to make their lives easier, more accessible, and safer.

Batu of CondoChance Team

BSc. Electrical Engineer & MBA
10+ years of industrial experience as an Electrical Engineer

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