Image of a candle which was the origination of the word "candela" that is Latin for candle.

Candela vs Nits: Measurement, Differences & Importance

With the advent of smartphone technology and advanced display technology, brightness is always a big deal. People want brighter screens so that they can see content clearly and vividly. But how do we measure brightness? Do we just say that we want something bright? Is there a number or metric we can use? 

That’s what we’ll talk about in this article. There has been a long-standing debate about candela vs nits. Are these two metric terms the same? Or are they different? Candela is a term that’s not usually mentioned in brochures and advertisements. But Nits, on the other hand, is a frequent term you’ll see.

In this article, we’ll end this long-standing debate and confusion by providing you with the answers you need.

Defining Candela

The candela (symbol: cd) is the measurement of luminous intensity. The human eye can’t see light unless light rays hit the retina. Because of that, candela is something that we can’t really see in a third-person perspective. The light must first hit our eyes before we can see.

To facilitate this, we measure candela as it hits a surface, which we call this luminance. We express luminance as candela per square meter or as:


The term cd/m2 is also called luminance, wherein we divide luminous intensity (cd) by the area (m2). In other words, we can only see light when it reaches our eyes. Light particles bounce from the surface and reach our eyes. That’s why luminance is the brightness of light based on the human eye’s perception of light. Naturally, light will scatter over an area. If light has more intensity, it will look so bright that the eyes will barely see the surface where the light is directed.

It is called candela because of its Latin etymology. Before Thomas Edison invented the light bulb, people used candles as the main source of light at night. . So if you want to do some science experiment, get a candle and go to a dark room. Light the candle and observe the areas that the candle lights. That’s one candela.

Defining Nits

You’ve probably heard of nits. It’s a common term used by tech reviewers when reviewing smartphone and tablet screens. Well, that’s the definition of nits. More nits mean brighter display.

Nits are an important number for displays because. Lower nits in a smartphone are not entirely bad until you are outside and under direct sunlight. You’ll notice that you can’t even see what’s on the smartphone screen. You still need to go a shade just to see the screen. That’s why higher nits are preferred most of the time.

Higher nits mean that brighter light sources like sunlight won’t easily beat weaker light sources. Even if you’re under direct sunlight, having higher nits would mean that you can still clearly see the contents on the screen.

Candela vs Nits: What’s the Difference?

We hate to break it to you, but there’s no difference between candela and nits. Yes, you read that right. Candela, nits, or cd/m2 are all the same. It really depends on your preference, and it won’t really matter. You can use them interchangeably, but you’ll probably want to stick with nits because they are the most common and popular term.

So why is that? Well, it has a certain ring on it. It’s easy to remember and not difficult to pronounce. Candela is fine, but it sounds too archaic. It just won’t sit well with the latest technology nowadays. Just imagine hearing, “How many candelas does that LED screen have?” It’s quite unsettling to hear and definitely not a good thing for marketing. 

Hence, whether you’re using candela or nits as a term for brightness, it won’t matter. You just need to prepare an explanation just in case someone asks what candela means. It’s not a common term, and everyone’s more familiar with nits nowadays. So that’s your caveat right there.

Why Is Luminance Measurement Important?

When you’re trying to figure out how good a display is, you often look at something called “luminance.” Technically speaking, that’s how it should be called. Luminance tells you how bright the light coming from the source is. However, instead of saying luminance, we often refer to it as nits. 

But have you asked yourself why luminance measurement is important? Let’s check out the reasons why:

  1. Seeing things clearly: It helps us see things better. If there isn’t enough luminance, our eyes won’t be able to clearly see anything, whether it’s lit by a light source or from a screen. It’s important to remember that luminance plays a vital role in the quality of screens and displays in the market today. If it isn’t clear, it’s not worth buying.
  2. Choosing lights and displays: Luminance measurement is helpful if we’re choosing the kind of light or display. For instance, if we need to light up a large area, we might need to use a light with a brighter luminance so that it can make the whole place bright. Displays also use luminance, especially when it is used. Brighter luminance or higher nits are needed for outdoor displays since sunlight can overpower the display.
  3. Making brighter screens: Luminance helps us set the right brightness of screen displays. Nowadays, people want the best experience possible. It must be bright enough that all the colors are seen properly.
  4. Achieving visual comfort: One of the reasons for having poor eyesight is either being exposed to so much light or little light. If you’ve tried reading in a dim area, your eyes are having a hard time seeing the text. Hence, you should have enough lightning to avoid eye strain. The same thing goes for too much light. If the light is too bright or changes a lot, it can be uncomfortable to the eye. Enough luminance makes it easy for our eyes to see and perceive things.
  5. Studying photometry: Photometry is the study of light as perceived by the human eye. Luminance is an important concept in photometry. In photometry, light is studied through its different wavelengths.
  6. Estimating energy use: Brighter screens use more energy. Manufacturers consider luminance when providing an estimated energy consumption of the screen. Some buyers are concerned about energy consumption, so they need to be aware of the product’s energy use over time.
  7. Creating effective navigation signs: For road safety, signs must be visible to motorists at all times. During the day, the sign must have enough luminance so that motorists can clearly see what it’s telling them. During the night, the sign must also be bright, even from afar, so that motorists can safely change lanes before turning or exiting the highway.

Understanding Luminance, Luminous Intensity, Luminous Flux, and Illuminance

Image showing the luminance, illuminance, luminous intensity, and luminous flux. In understanding candela vs nits, it's important that other concepts of light are discussed as well.
Luminance, Illuminance, and Lumens (Source: Faro Barcelona)

When talking about luminance and candelas, skipping luminous flux and illuminance is inevitable. The image above shows the interaction between luminance, lux, candelas, and lumens. Our focus in this article is luminance. We can see in the above image that luminance is perceived by the human eye.

Take note of the area lit by the candle. The light bounces from the area and goes to the human eye. Hence, it clearly states that luminance is the light we see as it touches a surface. Now, pay attention to the candle. The light coming out from the candle’s fire is the luminous intensity that’s measured using the unit candela. 

Luminous intensity is the brightness of light coming from the source. Luminance, on the other hand, is the brightness of light as it hits a surface. There’s a difference between the two. Now, let’s pay attention to lumens and lux. When light hits a surface, it brightens up the area, enabling us to see the surface. This is called illuminance. It is lumens per square meter.

How Scientists Use Candela

Luminance is an important concept in photometry and in understanding the dynamics behind display screens such as computer monitors or giant screens. Scientists always refer to luminance in its metric form as “cd/m².” This form enables scientists to have a quantifiable measurement of luminance.

In industrial and commercial applications, luminance helps manufacturers, inventors, and designers to use appropriate lighting for different uses. Luminance is important in our daily lives. In schools, enough luminance ensures that students have enough lighting to make it easier to see things and participate in classroom activities.

In offices, the same principle applies. Having enough luminance is conducive to working, especially if employees are working in front of monitor screens. If the office is dark, employees will experience eye strain from the bright monitor screens. Hence, it’s important that the office lighting will balance out the brightness of the computer monitor to prevent eye strain.

Medical professionals also have specific luminance requirements for lighting equipment used in surgeries and laboratories. The light must be bright so that surgeons can clearly see what they’re doing on the operating table. Scientists in laboratories also use light at different intensities, especially for experiments that are light-sensitive. It helps keep images looking bright and clear, as doctors do when they look at X-ray scans.

Think about places outside, like roads or parks. Luminance helps decide how bright the lights should be to keep everyone safe and make everything look nice. Also, the lights must be bright enough so that the beauty of the place is still recognized even after dark.

In consumer technology, luminance is also considered. The brightness of the screen affects the user experience. When the nits are too low, the device might be unusable outdoors because the users won’t see what’s on the screen. If the nits are too high, it’s possible that the device will use too much power or cause eye strain to the users.

In summary, the cd/m2 unit is like a ruler for measuring brightness. It helps scientists, builders, and designers make sure their lights and displays are as good as they want them to be.

How Scientists Use Nits

Nits is a popular term because a lot of technology utilizes screens like smartphones, smartwatches, smart refrigerators, and many more. You’ll hear tech reviewers mentioning nits more often nowadays. Whether it’s your computer screen, TV, or phone, nits play a major factor in your buying decision. Of course, we want the best value for our money, and higher nits are a good sign for better usability. 

Basically, it controls how much light the display gives off and how easily we can see content on our screens. The higher the nits value, the brighter the display is, especially in places with good lighting. A brighter display is ideal outdoors, so you may want to choose a device with higher nits for outdoor use.

Nits are also crucial for special types of content. If you’ve heard of high dynamic range or HDR, this imaging technology enhances the quality of the video or image. And to achieve optimal HDR experience, we need higher nits for that. Because of online video streaming services, people nowadays prefer to watch films and videos on their smartphones, tablets, and laptops. HDR displays improve the contrast and colors of the video, making it more realistic and vibrant. 

HDR content has a wider range of brightness, and higher nits are required. Since HDR makes blacks darker than usual, higher nits further highlight the visible colors on the screen. And if you’re using LED screens, HDR content is way better because of how LED works. It’s important to have high nits for HDR displays to maximize the viewing experience.

Outdoor displays need to be bright enough to be seen clearly, even in broad daylight. If sunlight will overpower the display, you’ll only see the screen panels, not the content shown on the screen. Knowing how many nits are needed enables manufacturers to create outdoor screen displays based on different uses and applications. 

Nits are used to ensure displays are set up just right. We don’t want displays to be too bright or too dark. Moreover, we also use nits so that we can program displays to be brighter during the day and darker during the night. Nits help in showing colors and brightness consistently. During the day, more nits are needed. But during the night, fewer nits are needed because it’s already dark, and content can be easily seen at low brightness.

Different industries have their own rules about how bright displays should be. For example, indoor lightning must have a minimum of 300 nits. It’s the optimal level for comfortable reading or viewing. Outdoor devices need to have at least 1,000 nits to be sunlight-readable. However, going as high as 2,000 nits is fine as well so that there’s less effort for the eyes to read the content on the screen.

It goes without saying that more nits mean more energy. If you are using a display strictly for indoor use, you may want to get display panels with lower nits, like 300 to 500 nits. Outdoor screens require more nits, so it’s best to get a display panel with a minimum of 1,000 nits. But with LED displays nowadays, you can save on electricity costs and still get the brightness you require. We highly recommend LEDs for cost efficiency.

Candela vs Nits: When To Use Each Term

Though candela and nits are interchangeable, there are certain contexts wherein one is more appropriate than the other. We provide some reasons below for the use of candela or nits more appropriately.

Firstly, you should consider where you’re using the term. Knowing the industry and context of the conversation is important in determining which term is better. The word “nit” is often linked to display and screen brightness. So if you’re buying a smartphone or television, using nit is more appropriate. Moreover, if you’re checking product brochures, you can easily spot the screen brightness if you see nits in the product specifications.

However, if you’re reading scientific journals, reports, and studies, researchers and scientists usually use candela instead of nits. To be more specific, they don’t even use the term candela. They always refer to it as candela per square meter or cd/m2.

Aside from that, you should also think about your audience. Are they knowledgeable about nits and candela? Are they more familiar with nits than candela? Do they even have a clue about what nits or candela mean? If you’re talking to experts in fields like photometry or lighting design, they’ll probably understand candela or candela per square meter. But if your audience is more general, they might find “nits” easier to understand. If nits still don’t ring a bell, using “screen brightness” is fine. 

Another reason to use candela instead of nits is if you want to be more precise. Candela per square meter (cd/m2) is the official metric term for describing luminance. Moreover, it’s the preferred term to use if calculations are involved. For example, if you want to determine the candelas needed to cover a specific area, it’s easy to derive the formula.

Caveats in Measuring Luminance

While it’s easy to calculate luminance as cd/m2, there are a lot of factors affecting luminance. First, brightness is dependent on how our eyes perceive light. It is subjective, to say the least. For example, someone with less-than-perfect eyesight may not see well under certain lighting conditions, especially those with eye diseases or problems. Other factors like visual sharpness, sensitivity to different brightness levels, and other conditions can affect how bright something appears to us.

Second, light-emitting devices have different ways of producing light. There are different lighting devices today, such as LEDs and LCDs. Before these two technologies, CRTs or cathode ray tubes were the popular screen displays. LEDs and LCDs have different ways of emitting light. For example, LEDs emit light when electricity passes through the diode. LCDs, on the other hand, don’t emit light. It is the panel behind the liquid crystal that emits light. With those differences, we can say that lighting devices may yield different luminance levels. 

Third, the quality of the content may also impact the luminance or brightness of the screen. Assuming there are no problems with the screen, it’s possible that the video or picture shown on the screen is intentionally dark or dim. Even if you blow it up to 1,000 nits, a video edited to be darker wouldn’t lighten up even if you max your screen brightness.

Fourth, external light may affect the luminance of the screen. A more overpowering light from the outside may affect how you see the content on the screen. It’s best to measure luminance in a dark area with minimal light.

Fifth and last, the screen settings may need adjustment if it’s not too bright. On television screens, you can adjust the brightness and contrast of the screen using the TV’s controls. Sometimes, manufacturers don’t maximize screen brightness by default. If you feel that the TV is not bright enough, check the settings to see if it can still be adjusted to a higher brightness level.

Overall, luminance measurement as cd/m2 isn’t fixed. There are a lot of factors involved in measuring luminance and the environment surrounding you affects such measurement. There will definitely be a lot of math involved in the calculations. But it’s best to leave them to the experts.


Brightness remains to be a tech specification that most tech buyers will consider in making a decision. Quantifying brightness helps tech buyers assess if the device can produce the right amount of brightness for their needs. The debate between candela and nits is actually due to its technicality. Some people aren’t familiar with candela while most are familiar with nits.

Candela, although not as widely used in tech products, is the standard unit and term for measuring luminous intensity. To measure luminance, we compute candela per square meter or cd/m2 to determine the brightness of light as it hits a surface.

On the flip side, nit is a more popular term commonly mentioned in tech reviews and product specifications. Nit is the unit used to describe how bright a display can reach. A higher nit count means a brighter display. Otherwise, a lower nit count means a dimmer display.

Since there are a lot of misconceptions about these two terms, candela and nits are the same. Regardless of the term you use, the concept and context remain the same.

And finally, whether we use candela or nits, we’re still referring to the brightness of the screen. Candela is more appropriate for scientific and academic use while nits is more popular for industrial and commercial use. But at the end of the day, both are the same.

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