Candlepower vs. Lumens: Differences and How to Convert

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When shopping for lightbulbs or researching flashlights, you‘ll inevitably come across technical terms like "lumens" and "candlepower." But what do these units actually measure? And what can they tell you about a lighting product‘s brightness and performance?

In this comprehensive guide, we‘ll cover everything you need to know about candlepower vs. lumens. You‘ll learn:

• The history and original purpose behind candlepower as a measurement
• How the lumen emerged as an improved standard for quantifying light
• The key differences between what candlepower and lumens measure
• How to convert between candlepower and lumens
• When to pay attention to each metric based on your lighting needs

Let‘s shine some light on decoding these measurement terms!

The Dawn of Artificial Lighting

Throughout human history, innovators have pushed lighting technology forward to extend our productive hours and illuminate interior spaces. As far back as 3500 BCE, Ancient Egyptians developed convex oil lamps to concentrate and direct candlepower.

Beeswax and animal fat candles later revolutionized portable illumination. Workshops specialized in intricate candle-making techniques to enhance burn time, like braided wicks and consistent candle diameters. Candlepower from open flames remained humanity‘s primary artificial light source for thousands of years.

In the 18th century, spermaceti oil from sperm whales boosted lighting capacity even further in American colonies. Whale oil lamps shone over 100 times brighter than tallow candles! But within a century, unchecked whaling decimated global sperm whale populations. Alternative fuel sources were desperately needed.

The 1850s brought the kerosene revolution. Abraham Gesner, a Canadian geologist, developed a process to distill illuminating oil from coal, bitumen and oil shale. Kerosene quickly replaced whale oil for lighting homes and lighthouses. It burned cleaner and more efficiently than other fuels. Specialized lamps were designed to combust kerosene safely and generate optimal candlepower.

Yet, the true lighting revolution was still to come…

The Dawn of the Electric Light Bulb

In 1879, Thomas Edison shocked the world by demonstrating a working electric incandescent light bulb. After testing over 6000 plant materials as filaments, he settled on carbonized bamboo. His prototype bulbs burned for over 1200 hours – greatly surpassing other artificial lights of the time.

Within a year, Edison Light Company was formed to manufacture and sell electric bulbs commercially. Homes and businesses began switching from gas lamps to Edison‘s miraculous bulbs. By 1920, electricity had surpassed gas lighting in many major U.S. cities. The era of electric illumination had arrived!

Introducing "Candlepower" for Comparing Brightness

This revolutionary new technology presented a challenge: how could you describe the brightness of an electric bulb compared to familiar candle flames? Thus, the candlepower standard was born.

One candlepower was defined as equal in luminous intensity to one candle flame. Now electric bulbs could be rated in candlepower equivalents to help consumers relate. A 50 candlepower bulb shone as bright as 50 candles! Candlepower gave the exciting new lamps context.

By 1930, over 80 billion candlepower worth of electric lights had been installed in the United States – equivalent to over 6 billion candles burning at once!

Of course, electric bulbs distribute light in spheres, whereas candle flames emit directionally. Voltage fluctuations also impact bulb output. As lighting technology continued advancing, a new measurement standard was needed…enter the "lumen."

Lumens: A Better Way to Measure Light

By the 1930s, the International Commission on Illumination (CIE) recognized candlepower‘s shortcomings for accurately quantifying electric lighting. In 1937, the CIE adopted the "lumen" as the standard international (SI) unit of luminous flux.

The lumen measures the total quantity of visible light emitted by a source in all directions. One lumen equals the illumination provided by one candela shining on one square foot of surface area.

So while candlepower measures the intensity of light in a single direction, lumens captures the sum total light output.

The Rise of the Lumen Measurement

Unlike candles, light bulbs and lamps distribute illumination across a 360-degree area. For these omnidirectional sources, lumens give a true representation of brightness.

By 1960, the lumen had become the predominant way to quantify artificial lighting across the lighting industry.

The chart below shows the rapid adoption of lumens for specifying bulb brightness over candlepower:

Lumens remain the standard today for quantifying illumination. Most residential lighting, like bulbs and fixtures, will be rated in lumens rather than the outdated candlepower.

Now let‘s do a side-by-side comparison of these two measurements.

Candlepower vs. Lumens – Key Differences

Although both quantify luminosity, candlepower and lumens measure different aspects of light output:

So candlepower rates only the maximum beam intensity, whereas lumens quantifies total light across all angles.

An Example

Imagine a 100-watt incandescent bulb and a tactical flashlight, each rated at 1000 candlepower.

• The bulb emits over 1500 lumens of light in a 360-degree sphere.

• The flashlight concentrates 1000 candlepower into a narrow directional beam.

So despite the equal candlepower ratings, the overall light output is quite different. This demonstrates why lumens provide a more meaningful measurement of brightness for typical household lighting.

Converting Between Candlepower and Lumens

When comparing lighting products, you may need to convert between candlepower and lumens. Here’s the basic formula:

To convert candlepower to lumens, multiply the candlepower by 12.57.

For example:
300 candlepower x 12.57 = 3771 lumens

To convert lumens to candlepower, divide the lumens by 0.07958.

For example:

5000 lumens / 0.07958 = 62859 candlepower

Try out the interactive calculator below to see candlepower and lumens conversions:

[Insert lumen/candlepower converter tool]

Being able to convert between units allows you to compare specs and make informed lighting purchases.

When to Pay Attention to Each Metric

As you evaluate lighting options, when should you focus on lumens vs. candlepower?

For ambient lighting, lumens will generally tell you most everything you need to know. The greater the lumen rating, the brighter the illumination.

For directional lighting like flashlights or spotlights, consider both metrics:

• Lumens indicates overall light output from the source

• Candlepower tells intensity of the brightest focused beam

A tactical flashlight with high candlepower will concentrate its lumens into an intense spotlight beam that reaches farther.

So both measurements have relevance depending on your lighting purpose and beam characteristics.

Choosing the Right Lumens for Your Space

When upgrading lighting, how many lumens should you look for? It depends on where the lights will be used:

Task lighting: Opt for 800-1300+ lumens under cabinets, work lamps, or anywhere you need high visibility for handling detailed tasks.

Ambient lighting: Living rooms, bedrooms, and relaxed spaces typically only require 400-800 lumens for general illumination.

Directional accent lighting: Downlights, track heads, or accent spots can get by with 200-400 lumens since the light concentrates on specific areas.

Outdoor lighting: For large patios, walkways, or driveway coverage, look for 1200+ lumens. Consider light spread patterns when positioning.

Online lumens calculators can provide personalized recommendations based on your room size and activities. Combine ample ambient lighting with concentrated task lighting for optimal visibility.

The Ongoing Pursuit of Quality Lighting

Thanks to pioneering scientists, we‘ve come a long way from candles and oil lamps! Thomas Edison helped pave the path to modern electricity-powered illumination. Outdated candlepower measurements gave way to standard lumen units.

Yet our quest for the ideal quality and quantity of light continues today. New technologies like LEDs and smart lighting provide more control over our luminous environments than ever before. But the metrics we use to evaluate artificial lighting still trace back to those original candle flames.

So next time you see lighting specifications in lumens or the seldom-used candlepower, appreciate the centuries of progress and persistence in humanity’s illumination journey. Keep pushing forward into the future of lighting!