What is the intensity of light? & devices to measure it

One rainy day you go to your home office to get some work done. Since the sun was hiding behind the gray clouds, you had no choice but to switch on the lights. As you did, nothing happened. You tried again and again, but the room stayed dim and gloomy. It wasn’t long before your mood began to match the overcast day.

If this happened to you, lighten up – you don’t need to revert to using candles and oil lamps. Chances are, your bulbs aren’t bright enough. If you’ve been wondering about the intensity of light and how to measure it, continue reading this article as we explain it in detail.


The intensity of light is used to measure its strength and is denoted in lumens. Lumens can be used to compare different light sources. The best way to measure light intensity is with a device like the one from Leaton that can easily get readings.

In this article, we’ll also go over the following topics:

  • How lumens affect photosynthesis
  • Whether you need a ring light
18-inch ring light

Table of Contents

What is light?

Light is just a small fraction of electromagnetic radiation. It’s also the only part of the spectrum humans can see, thanks to the photoreceptors in our eyes. Plants contain a substance called chlorophyll which can ‘harvest’ visible light and use its energy to convert inorganic matter into biomass.

Each wavelength of visible light has its specific color. When they combine, it appears white. Objects absorb certain wavelengths and reflect the rest. We perceive these reflected wavelengths as colors.

What is the intensity of light?

Extech LT300 Light Meter

The intensity of light tells us how much of it falls on a surface of a known size. Unless you’re into physics, illuminance is the only metric you’ll need to know. It is measured as lumens (the amount of light) per square unit, usually square foot (footcandle) or square meter.

Although the number alone won’t tell you much, it can be used to compare the brightness of two different sources. Moreover, experts recommend certain values for each type of room. Not only does this ensure that you can see in the room, but it may also promote productivity.

Devices to measure light intensity

Pyle PLMT16 Light Meter turned off

Devices used to measure this intensity are called light (sometimes lux) meters. Though they are most useful to professional photographers, you might also benefit from buying them. You must meet certain brightness requirements when designing your dream house. With a lux meter, you’ll be able to tell if your lighting meets these standards or not. 

You might feel blinded by the sheer amount of options on the market. Fortunately, we’ve narrowed down the search for you. 


This cost-efficient digital meter will brighten your day. For such a cheap model, it’s incredibly accurate. It measures not only in footcandles but also in lux. Our non-US readers will surely be relieved to hear that. If you wish to measure the brightness in your house, then this light meter will be more than enough.


  • Attractive price
  • High accuracy
  • We love how we can change the measuring format


  • The manual is not in English
  • Not ideal for photography
One of the most accurate meters.
Item Weight‎4.8 ounces
Package Dimensions‎6.5 x 3.6 x 1.6 inches
Power Source‎Battery Powered


For professional photographers, we recommend this HOLDPEAK meter. It can measure light intensity up to 40,000 FC, a superb range. Especially for such a great price. It features a rotatable sensor, so using it couldn’t be easier. No flapping and stretching is required to get the reading! You can also store the read values to compare them later.


  • The Backlight function makes the screen brighter
  • We appreciate the fast delivery


  • The batteries included have a short life
Ideal for your garden.
Batteries‎2 AAA batteries required. (included)
Battery Cell Type‎Alkaline
Item Weight‎7.8 ounces
Power Source‎Battery Powered
Product Dimensions‎8.19 x 4.25 x 1.69 inches


All gardeners will love this light meter. Checking your bulbs’ performance couldn’t be simpler thanks to its flexible sensor and great measuring capacity. You can also store measured data with this model. Though originally intended for a greenhouse, you can use it practically anywhere in your house.


  • The display is advanced
  • We found it useful in our garage work too


  • It can overheat
Digital Light Meters AP-8801A
This one has an advanced display with several features included.
Package Dimensions8.19 x 4.29 x 1.81 inches
Power Source TypeBattery Powered
Weight1.17 Pounds

Fortunately, measuring the light intensity in your home couldn’t be easier. All you need is a light meter.

Here’s our simple guide:

How to measure the intensity of light

  1. Choose the room where you want to measure the intensity and switch off every light source.

  2. Use the meter to get the baseline measurement.

    It is the natural ambient light in your room.

  3. Annul the reading and switch the lights back on.

  4. Stand in the center of the room and measure the new intensity.

  5. Subtract the baseline measurement from the value you measured when the lights were on.

    It will tell you how much light the existing sources produce.

  6. Repeat in other rooms of the house.

Light intensity units

You’ll need to learn these four important units to understand illuminance better.


Lumens are units that measure how much visible light a source emits over a set time. When buying bulbs, you might notice their lumen written on the package. The higher the value, the brighter the bulb.


A footcandle is a unit of illuminance. It denotes how many lumens fall on one square foot.


Lux is another unit used to measure illuminance. However, it is defined as the number of lumens that falls on one square meter.

Watts vs. Lumens

Gossen Scout 3 light meter

While wattage can help you determine how much power the bulb will consume, it doesn’t tell you anything about its brightness. The higher the wattage, the more electric power the bulb needs to operate. Thus, you can expect your electric bills to go up as well. Look for lumens on the package to check how bright the bulb will be.

The next time you go shopping for light bulbs, use the table below for guidance.

150 W2600 lm
100 W1600 lm
75 W1100 lm
60 W800 lm
40 W450 lm

Why you should measure light intensity

You might be wondering why you should even bother with measuring light intensity. For one, every room has its specific standard recommended according to its use. In industrial settings, these standards may become requirements. Failure to meet them could result in work accidents.

If you are a photographer, you can’t do without measuring the brightness when taking pictures. Everyone knows that the right lighting is what makes a good photo. The same goes for video production. Better lighting means higher quality, whether you are a professional cameraman or an aspiring YouTuber.

As technology progresses, many cameras already have an in-built lighting intensity meter. But a separate meter might be a good investment if you’re using an outdated model.

Measuring the ambient brightness can also be useful outdoors. By evaluating how much light falls on a certain area, you can determine whether it is a good spot for a solar panel. In addition, you also tell if your plants are getting enough sun rays to develop properly.

It’s also used in theaters to determine if the stage is lit well enough.

light meter

How does light intensity impact our productivity?

Ages ago, we relied on the sun to determine when to work and when to sleep. Once it fell behind the western horizon, it was pointless to keep working since we couldn’t see anything. Though we could use fire to illuminate our surroundings, it wasn’t bright enough.

That’s no longer the case in the contemporary era. We are no longer tied to the sun. We spend a lot more time indoors. Some people even have jobs that make them rely on artificial lighting, even during the day. Conversely, other people work well into the night. It negatively impacts our sleep-wake cycles.

Daylight used to tell us that it was time to be awake. But artificial lighting can’t compare to the sun. And at night, it shines much more brightly than the stars and the moon. As a result, many of us feel exhausted during the day. This exhaustion makes it harder for us to focus, which lowers our productivity. We also have a much harder time falling asleep at night.

When designing your house, ensure you have enough windows in every room. No bulb can match the sun in terms of intensity.

How does light intensity affect the rate of photosynthesis?

Pyle PLMT16 Light Meter

Tending a vegetable garden can be a pleasant hobby. It’s always satisfying to see your hard work bear fruit. In this case, vegetables. Not to mention it’s a nice distraction from your monotonous daily life.

However, not everyone can afford to enjoy this lovely pastime. Perhaps your unfortunate location stands in the way. After all, very few things grow in deserts. Or maybe you can’t afford a yard.

Well, there are no problems, only solutions. Thanks to modern technology, you can cultivate your vegetable patch indoors. But when choosing the right bulb for your indoor crops, you must consider its intensity.

Unlike humans, plants make their own ‘food.’ They convert carbon dioxide into simple sugars using visible light as fuel.

All organic carbon originates from plants. Since light drives this complex chemical reaction, it’s only logical to think that more light will speed up the process. While this is true, it is not the only factor that affects photosynthesis.

There are many benefits of using grow lights for your plants. Some of them are:

  • Fast growth
  • Larger plant growth
  • Using less energy than normal lights
  • You can grow plants in any climate
  • Directly control the amount of light
  • Grow more flowers at the same time

As mentioned before, plants use carbon dioxide as building blocks for simple sugars. Thus, its concentration in the environment will also affect the rate of photosynthesis. The extra brightness won’t help much if there is no material to work with.

Temperature also plays a part. Higher temperature makes photosynthesis faster. Light bulbs generally don’t produce that much heat, and you will need a heater for your plant room. But don’t overdo it. In extremely high temperatures, enzymes degrade. Without them, the entire process will come to a halt, and your plants will die.

To summarize, photosynthesis will occur faster at higher light intensities but only until another factor becomes limiting.

What is a ring light?

12-inch ring light

True to its name, a ring light is a circular light source. They cast evenly distributed light on the subject. It is why they are used in surgical theatres or above the dentist’s chair. But nowadays, they’re readily available on the market.

Why would you need one? Well, these devices are essential for every good photographer. After all, it’s proper lighting that makes a good photo. Because ring lights provide even lighting, there won’t be any shadow in the picture. If you ever wondered why people look so stunning in business card portraits, odds are they used this ingenious invention.

You will find this product useful if:

  • You are a live streamer
  • You are a make-up artist
  • You want to take cool photos on your travel
  • Attend online conferences often
  • Record videos of yourself

The same holds true for videos. Thanks to ring lights, actors in commercials always look professional and beautiful. It might be an excellent investment early on if you are an aspiring YouTuber. You usually place the camera inside the ring light to ensure even illumination.

Make-up artists can also put them to good use. The balanced brightness allows you to pay closer attention to even the finest of details.

Ring light

Did you find these devices enlightening? Perhaps you’re even considering buying one. If so, here are some of our suggestions:


Many corporations switched to home-office in the dark days when Corona ravaged the world. Because it turned out to work so well, many chose to keep it this way. Though online meetings are much more comfortable than real ones, sometimes it might be difficult to display your best self.

This cute little product from Tantuu can easily change that. With so many options, you’re bound to look radiant every day. Thanks to its flexible clip, you can pin it on laptops, monitors, or even desk lamps. Whether you’re a Twitch streamer or a businessman, you can’t go wrong with this option.


  • The cord is long
  • You can pin it on your laptop thanks to the flexible clip


  • You will feel uncomfortable if you wear glasses
TANTUU Ring Light
The flexible clip is one of its features.


For professional photographers out there, we recommend this Neewer product. It comes with an adjustable neck, so you’ll be able to create the perfect lighting for your subjects. Moreover, the bulbs are dimmable. The package comes with two color filters (white and yellow). You couldn’t ask for a better piece of equipment to much your photography skills!


  • An adjustable neck is essential for photographers.
  • We made good use of the two color filters included


  • Screws are tightly screwed
  • Instructions are difficult to understand
Neewer Ring Light
This one has two filters included.


If you’re looking for something between the previous choices, consider getting this SENSYNE product. Thanks to its phone holder, you’ll be able to shoot your make-up tutorials easily. It’s also perfect for recording meetings or birthday parties.


  • Fits all the requirements of a streamer
  • We love the adjustable brightness function


  • The package took a long time to arrive
Sensyne 10'' Ring Light
If you are LIVE on Tiktok and Instagram often, this one is for you.

High-intensity light bulbs

Do you sometimes feel as if you still lived in the medieval age? Does your home feel like an ancient catacomb lit by poorly burning torches? Then it’s time to throw your bulbs into the bin and new ones.

Here are some high-intensity bulbs we recommend:


This SLEEKLIGHTING package comes with four high-intensity spiral bulbs. These bulbs pack quite the punch, producing 1600 lumens. Because they last up to 10,000 hours, you won’t need to replace them often. These fluorescent bulbs have a wattage of 23 watts.


  • These spiral bulbs will last a long time
  • It will light up a large area


  • Problems with shipping; some bulbs arrived broken
These spiral bulbs are very powerful.


With the dazzling luminous flux of 900 lumens, these halogen bulbs will brighten even the darkest corners of your house. They have a life expectancy of 3000 hours. Their wattage is 50 watts. Most importantly, they are great value for money compared to other options.


  • Easy to install, anyone can replace these
  • Great value for the money


  • Bulbs don’t last very long
These spiral bulbs are very powerful.


The FanNicco corn bulbs are as bright as they come, generating up to 5500 Lumens worth of light. Though somewhat costlier than other bulbs on our list, they will last you for breathtaking 36,000 hours. Their wattage is 60 watts.


  • We found good use of these bulbs in our garage
  • A lot of lumens at an affordable price


  • The light bulbs can overheat during summer when temperatures are high
One of the most powerful lightbulbs on the market.


What are the types of light intensity?

The types are luminous intensity, luminous flux, illuminance, and luminance. However, you only need to know illuminance and luminous flux to measure brightness in everyday life.

Luminous flux is defined as the total energy that a source emits as light. Its units are lumens.

Illuminance is the number of lumens that fall on a set surface area. If this area is one square meter, the unit is called lux. In case it’s a square foot, it’s measured in footcandles.

Why is measuring light intensity important?

Measuring brightness in the environment is essential when you design your home. You’ll have to meet certain lighting standards to make the rooms safe.

The intensity is also essential for every photographer and video producer. Shooting in a dim room will result in poor-quality photos or videos. With a lux meter, these professionals can determine whether the brightness is good enough before they even begin the shoot.

It’s also useful in agriculture. With a lux meter, you can tell if your plants are getting enough sustenance.

What determines the intensity of light?

The bulb type plays a huge role in determining how bright your room will be. When shopping for the right bulb, check its luminous flux. Many people only look for watts, but this is a mistake. While wattage might help you predict electricity bills, it won’t tell you much about the bulb’s brightness. Always check the lumens when buying one.

The number of bulbs can also separate a dim room from a well-lit one. The more bulbs you have, the brighter it’s going to be. Don’t overdo it, or you’ll have to pay extra for electricity.

Bulbs are not the only source of light in most rooms. Unless you live in a haunted crypt, your house likely has windows. Sunlight and moonlight also affect your house’s brightness. In urban areas, street lamps might also play a part at night. You should offset this lack of natural lighting for rooms with fewer windows with extra bulbs.


All told, the intensity of light is an important factor for not only photographers and video producers but also ordinary citizens. There are certain standards you should stick to when designing your rooms. In addition to preventing accidents, proper lighting can also boost your productivity. Measuring brightness in your home is a very simple process. All you need is a light meter.