# What is the Difference Between Lumens and Footcandles? Understanding Lighting Measurements

Have you ever wondered about the difference between lumens and footcandles? It’s a question that many people ask, and it’s a good one to have an answer to. The truth is that lumens and footcandles are measures of light, but they’re used in slightly different ways.

Lumens are a measure of the total amount of visible light emitted by a light source. In other words, it’s a measure of how much light is coming out of a bulb or fixture. You might see lumens listed on a package of light bulbs, for example, or on a specification sheet for a lighting product. Footcandles, on the other hand, are a measure of how much light is actually hitting a surface. This is an important distinction, because the amount of light that hits a surface is what determines how bright that surface will be. So while lumens tell you how much light is coming out of a bulb, footcandles tell you how much light is actually making it to your work surface, for example.

## The Importance of Measuring Light

Measuring the amount of light in a space is crucial for several reasons. Here are just a few:

• Ensuring proper illumination for specific tasks or activities
• Providing a safe and secure environment
• Reducing energy consumption and costs by using the appropriate lighting level
• Being mindful of the health and well-being of individuals through optimal lighting conditions

## The Difference between Lumens and Footcandles

When it comes to measuring light, there are two primary metrics used: lumens and footcandles. Lumens measure the total amount of visible light emitted by a light source. Footcandles measure the light intensity of a surface illuminated by the light source. Essentially, lumens measure the output of the light source while footcandles measure the amount of light received by a surface.

Here is a comparison table:

Lumens Footcandles
Measure light output of a light source Measure light intensity of a surface
Does not take into account the distance between the light source and surface Requires the distance between the light source and surface for an accurate reading
Typically used when discussing light bulbs or other light sources Typically used when discussing the amount of light needed on surfaces such as floors, tables, or walls

## Considerations when Measuring Light

When measuring light, there are several factors to consider:

• The purpose of the space and the activities that will take place in it
• The type of lighting needed, such as ambient, task, or accent lighting
• The color temperature of the light, which can affect mood, productivity, and visual clarity
• The location and distance between the light source and surface

By taking these considerations into account and using the appropriate metric, you can ensure optimal lighting conditions for your needs.

## Definition of Lumens

Lumens is a unit of measurement for light output. It is a measure of the total amount of light that a source emits in all directions. It is important to note that lumens measure the total light output of a source, regardless of the direction in which it is emitted.

## What is the difference between Lumens and footcandles?

• Lumens measure the total amount of light produced by a source.
• Footcandles measure the amount of light that falls on a given area.
• Lumens are measure of light at the source, whereas footcandles are a measure of light at a specific point in space or on surface.

## Why is understanding Lumens important?

Understanding Lumens is important because it helps you determine the brightness of a light source. It allows you to compare the brightness of different lights and determine which one is best suited for a particular task or activity. When buying light bulbs, lumens would tell you how bright the bulb is, so you can choose one with the appropriate brightness for your needs.

It is also important to note that lumens are not the only thing to consider when choosing a light source. The color temperature, color rendering index (CRI), and beam angle are also important factors to consider.

## The Lumens and Watts Conversion Table

Lumens Watts (incandescent bulbs) Watts (LED bulbs)
250 lm 25 W 4 W
450 lm 40 W 6 W
800 lm 60 W 10 W
1100 lm 75 W 12 W
1600 lm 100 W 16 W

This table shows the equivalent lumens and watts for incandescent and LED bulbs. As you can see, an LED bulb with 10 watts can produce the same amount of light (800 lumens) as a 60-watt incandescent bulb. This is because LEDs are much more efficient at converting electricity into light than incandescent bulbs.

## Definition of Footcandles

Footcandles, also known as lumens per square foot, are a measure of light intensity. Specifically, it calculates the amount of light that falls on a surface from a one-foot distance away from a standard light source. One footcandle can be expressed as one lumen of light that is spread across a square foot of space. This measurement is commonly used in lighting design to determine the appropriate amount of lighting needed for a particular environment, such as a room or a workspace.

• Footcandles are used to measure the amount of light in a specific area.
• They are measured in lumens per square foot and indicate the amount of light that falls on a surface.
• This measurement is crucial for lighting designers to determine the amount of light necessary for a particular space.

For example, if a workspace requires 50 footcandles of light, the lighting designer can determine the appropriate number of light fixtures needed and their positioning to achieve the desired lighting level.

Footcandles are often used in conjunction with lumens, which measure the total amount of light emitted by a light source. While lumens measure the total amount of light emitted, footcandles measure the intensity of that light on a specific surface.

Lumens Footcandles
1000 lumens 10 footcandles at 100 sq ft
2000 lumens 10 footcandles at 200 sq ft
3000 lumens 10 footcandles at 300 sq ft

Overall, footcandles are an essential measurement for determining the appropriate lighting levels for different spaces. With its measurement, lighting designers can ensure that the amount of light in an area is neither too bright nor too dim, creating an environment that is comfortable and efficient for its users.

## How Lumens are Measured

Before understanding how lumens are measured, it’s important to know what exactly a lumen is. A lumen is a unit of measurement for the brightness of a light source, also referred to as luminous flux. This means lumens measure the amount of light produced by a bulb or fixture. Footcandles, on the other hand, measure how bright the light is at a given distance.

Lumens are measured using a device called an integrating sphere. The sphere is coated with a highly reflective material and has a small opening where the light source can be placed. Once the light source is turned on, the sphere captures all the light and measures the total amount of lumens being produced.

## Methods for Measuring Lumens

• Photometry – measures the amount of light being produced by a bulb or fixture at a specific point in space
• Spectroradiometry – measures the entire spectrum of light being produced by a bulb or fixture
• Chromaticity – measures the color of the light being produced by a bulb or fixture

## Factors that Affect Lumens Measurement

There are several factors that can affect the measurement of lumens. The first is the distance between the light source and the integrating sphere. The closer the light source is to the sphere, the more accurate the measurement will be. Another factor is the temperature of the room. If the room is too warm, it can affect the accuracy of the measurement. Finally, the type of light source being measured can also affect the measurement. LED lights, for example, require a different method of measurement compared to traditional incandescent bulbs.

## Lumen Output Comparison Table

Bulb Type Average Lumen Output
Incandescent (40W) 450
Incandescent (60W) 800
Incandescent (100W) 1600
LED (5W) 450
LED (10W) 800
LED (15W) 1600

As you can see from the table, LED bulbs can produce the same amount of lumens as incandescent bulbs using significantly less power.

## How Footcandles are Measured

Now that we have an understanding of what footcandles are, let’s take a closer look at how they are measured. Footcandles are measured using a device called a light meter, which measures the amount of light at a specific point in a room or space. There are a few different types of light meters, but they all work by using a sensor that converts the amount of light it detects into an electrical signal. This signal is then displayed on a screen or meter and can be used to determine the number of footcandles in a given area.

• Hand-held light meters: These are the most common type of light meter and are used for measuring light in photography, film, and video production. They can be used to measure both ambient light and flash, and usually come with a variety of different attachments to suit different needs. Hand-held light meters are relatively affordable and easy to use, making them a popular choice for hobbyists and professionals alike.
• Digital light meters: These are similar to hand-held light meters, but instead of displaying the light reading on an analog screen, they have a digital readout. They are usually more precise than hand-held meters but are also more expensive. Digital light meters are often used in commercial and industrial applications where accuracy is crucial.
• Integrated light sensors: Many modern devices, such as smartphones and cameras, come with integrated light sensors that can be used to measure light levels. These sensors work by measuring the amount of light that hits the sensor and adjusting the camera settings accordingly. While not as accurate as dedicated light meters, integrated light sensors can be a useful tool for quick and easy light measurements.

It’s important to note that the distance between the light source and the sensor will affect the reading on the light meter. The closer the meter is to the light source, the higher the reading will be, and the farther away it is, the lower the reading will be. Because of this, it’s important to take measurements at the point where the light is actually needed, whether it’s on a desk, a workbench, or a photography set.

Recommended Light Levels (footcandles) Activity
50-100 General lighting for residential homes
200-400 Drawing, drafting, and detailed work
500-1000 Sewing, assembly, and inspection work
1000-2000 Painting, photography, and other visual tasks
2000-5000 Darkroom work, surgical procedures, and other specialized tasks

As you can see from the table above, recommended light levels vary depending on the activity being performed. For example, a photographer working in a darkroom will need much higher light levels than someone sitting at a desk working on a computer. By measuring footcandles, you can ensure that the lighting in your space is appropriate for the task at hand.

## Applications of Lumens and Footcandles

If you’re involved in lighting design or are simply interested in how lighting works, you’ve probably encountered the terms lumens and footcandles. Both are used to measure the amount of light in a space, but they’re not interchangeable – understanding the difference between the two is essential if you want to design effective lighting systems.

In this article, we’ll explore the applications of lumens and footcandles, and explain why they’re both important in lighting design.

• Choosing the Right Lightbulbs: Lumens are used to determine the brightness of a lightbulb. In general, the higher the number of lumens, the brighter the bulb will be. If you’re looking to light up a large space, you’ll want to choose a lightbulb with a high lumen output.
• Calculating Light Levels: Footcandles are used to measure the amount of light that falls on a surface. One footcandle is equal to one lumen per square foot, so if you know the number of footcandles you need in a space, you can calculate the number of lumens required to achieve that level of illumination. This is useful when designing lighting systems for specific tasks, such as reading or cooking.
• Optimizing Energy Efficiency: By understanding the relationship between lumens and footcandles, you can optimize the energy efficiency of your lighting system. By choosing the right lightbulb with the correct lumen output, you can achieve your desired level of illumination while using less energy. This is important for both environmental and economic reasons.

Now that we’ve discussed the practical applications of lumens and footcandles, let’s dive a bit deeper into how they’re used in lighting design.

In general, lumens are used to specify the amount of light required for a particular setting, while footcandles are used to determine the actual light levels in that setting. For example, if you want to illuminate a small reading area with a light level of 20 footcandles, you’ll need to choose a lightbulb with a lumen output that’s sufficient to achieve that level of illumination.

Footcandle levels can be measured using a light meter, which is a device that measures the amount of light falling on a surface. By taking readings at various points in a space, you can determine whether the lighting system is achieving the desired level of illumination.

Light Level Application
10 – 20 fc Residential settings, hallways
30 – 50 fc Office spaces, classrooms
75 – 100 fc Mechanical work areas, kitchens
200 – 300 fc Examination rooms, art studios

As you can see from the table above, different applications require different levels of illumination, and it’s important to choose the correct lighting system to achieve those levels. By understanding the relationship between lumens and footcandles, you can design lighting systems that are both effective and efficient.

## Comparing Lumens and Footcandles

When it comes to measuring the amount of light in a particular area, two commonly used measurements are lumens and footcandles. Although both of these measurements are used to determine the brightness of a light source, they are not interchangeable. In fact, they measure different aspects of light and can be used in different applications.

• What are Lumens?
Lumens are a measurement of the total amount of visible light that is emitted by a light source. When you are shopping for light bulbs, you will often see the term lumens used to describe the brightness of the bulb. In general, the higher the number of lumens, the brighter the light source will be.
• What are Footcandles?
Footcandles are a measurement of the amount of light that falls onto a surface. This measurement is used to determine the level of illumination in a particular area. For example, if you are designing a lighting system for a room, you would use footcandles to determine how much light is needed to adequately illuminate the space.
• What is the Difference Between the Two?
The key difference between lumens and footcandles is that lumens measure the total amount of light emitted by a source, while footcandles measure the intensity of the light on a surface. In other words, footcandles tell you how much light you need for a specific area, while lumens tell you how bright the light source will be in general.
• How are They Used?
Lumens are most commonly used when selecting light bulbs for a particular space, as they provide a good indication of how bright the bulb will be. However, they are not as useful when it comes to designing a lighting system, as they do not take into account the size or layout of the space. Footcandles, on the other hand, are specifically used for designing lighting systems, as they allow you to calculate the amount of light needed for a particular space.
• When Should You Use Each One?
If you are simply looking for a bulb to brighten up a room, lumens will be your best bet. However, if you are designing a lighting system for a specific space, you will want to use footcandles to determine the amount of light that is needed for the area.
• Which One is Better?
Neither lumens nor footcandles are inherently better than the other – it simply depends on what you are using them for. If you are looking to compare the brightness of different light sources, lumens will be the most useful. If you are designing a lighting system, footcandles will provide you with the information you need to create an optimal lighting solution.
• Summary
In summary, lumens and footcandles are both measurements of light, but they are used in different ways. Lumens measure the total amount of light emitted by a source, while footcandles measure the amount of light falling on a surface. While lumens are useful for comparing the brightness of different light sources, footcandles are essential for designing an optimal lighting system.

## References

In this table below, you can see a direct comparison between lumens and footcandles, which will help you to determine which measurement is best suited for your needs.

Lumens Footcandles
Measures the total amount of light emitted by a source Measures the amount of light that falls on a surface
Useful for comparing the brightness of different light sources Essential for designing an optimal lighting system
Does not take into account the size or layout of the space Takes into account the size and layout of the space
Can be used to select light bulbs for a particular space Can be used to calculate the amount of light needed for a particular space

Ultimately, the choice between lumens and footcandles will depend on the specific application in question. By understanding the differences between these two measurements, you can choose the best one for your particular needs and ensure that you have the right amount of light for any given space.

## What is the difference between lumens and footcandles?

### 1. What is a lumen?

A lumen is a unit of measurement that describes the amount of light emitted from a light source. It measures the perceived brightness or light output of a bulb.

### 2. What is a footcandle?

A footcandle is a unit of measurement that describes the amount of light that falls on a surface per square foot. It is a measure of illuminance or brightness at the surface.

### 3. How do lumens and footcandles relate to each other?

Lumens and footcandles are related but different. Lumens describe the total amount of light emitted by a source, while footcandles describe the amount of light that falls on a surface.

### 4. Which one should I use to measure the brightness of my light source?

If you want to measure the brightness of your light source, you should use lumens. However, if you want to measure the amount of light that shines on a surface, you should use footcandles.

### 5. Are lumens or footcandles more important?

Both lumens and footcandles are important measurements, but they serve different purposes. Lumens are important for measuring the brightness of a light source, while footcandles are important for measuring the illuminance or brightness at a surface.

## Closing Thoughts

Hopefully, this article has helped you understand the difference between lumens and footcandles. Remember, lumens measure the total amount of light emitted by a source, while footcandles measure the amount of light that falls on a surface. Thanks for reading, and be sure to visit us again for more helpful information!