Candlepower vs Lumens: A Complete Guide to Understanding and Converting Between Units

Candlepower and lumens are two key measurements used to quantify light from different sources. But what exactly is the difference between candlepower and lumens? And why are both units still used today? In this comprehensive guide, we’ll unravel the details behind candlepower and lumens to give you a clear understanding of these terms.

A Brief History

Since ancient times, candles have been essential for providing light during dark nights and long winters. Over thousands of years, humans became intimately familiar with the warm glow of candlelight. The brightness of different candle types became a yardstick for measuring light intensity.

In the late 1800s, electric lightbulbs emerged as a new, revolutionary technology. To help people wrap their heads around these novel electric lights, manufacturers described lightbulbs in relation to the familiar candle. The term “candlepower” was coined to quantify the intensity of electric lights in terms that could be easily understood. One candlepower was equivalent to the brightness of a single candle flame.

So originally, candlepower offered electric lighting manufacturers a convenient way to describe lightbulb capacity. But candlepower measures light intensity in one specific direction, not total light output. Eventually the standardized unit “lumen” was introduced to account for overall light across all directions from a source.

Despite some obsolescence, candlepower remains in use today for spotlighting and directed lighting applications where peak beam intensity is a key consideration. Meanwhile, lumens have become the predominant unit for general purpose lighting like bulbs and fixtures.

Candlepower vs. Lumens – Key Differences Explained

Below is a quick summary of how candlepower and lumens differ:

To understand this better, think of candlepower like water pressure – it measures the pounds per square inch at the strongest point of water flow, indicating water intensity. Lumens are more like water volume – quantifying the total amount of water flowing out regardless of pressure at any point.

High candlepower means a tightly focused, intense beam, while more lumens means greater overall light is produced. One candlepower equals around 12.5 lumens since intensity and total volume differ.

Converting Between Candlepower and Lumens

Because candlepower and lumens describe different (albeit related) aspects of light, conversions are necessary when comparing specs across lighting instruments:

To convert from lumens to candlepower, divide the lumens value by 12.57

Candlepower = Lumens / 12.57

To convert from candlepower to lumens, multiply the candlepower value by 12.57

Lumens = Candlepower x 12.57 

Let‘s see examples converting between 1000 lumens and 75 candlepower:

• 1000 lumens / 12.57 = 79.48 candlepower
• 75 candlepower x 12.57 = 942.99 lumens

So when converting between the two units, we see that intensity vs total output differs significantly even for round numbers.

Factors to Consider When Comparing Lumen and Candlepower Specs

When evaluating and contrasting lighting equipment, we need to consider more than just the raw lumens or candlepower rating. Here are key factors to weigh when comparing lights:

Beam Distance – how far the beam effectively travels before dimming determines if light reaches your target

Run Time – amount of time a light source can maintain claimed brightness

Beam Spread – width/dispersion of the light beam, from tight spot to wide flood

Color Temperature – warmer 2700K or cooler 5000K+; affects perceived brightness

Beam Pattern – even flood or focused hot center spot impacts overall visibility

So a handheld 400 lumen flashlight, 5000 lumen shop light, and 400 candlepower spotlight will have vastly different visibility in practice based on these other variables despite ballpark lumen/candlepower specs.

Consider beam intensity and throw versus total spread plus run duration for your specific needs. Using lumens or candlepower as a singular benchmark for “brightness” can be misleading unless accounted for beam width, color temperature, battery life, and other germane factors.

When to Use Lumen vs Candlepower Specifications

Given the extra context above, when should you pay more attention to lumens versus candlepower?

Lumens
General home/office lighting
Ambient ceiling lights
Under-cabinet fixtures
Bedside table lamps
Landscape lighting

Candlepower
Flashlights
Spotlights
Headlamps
Security lighting
Vehicle headlights

So for broadly illuminating spaces where uniform, all-direction light is desirable, lumens are the ideal specification to examine.

For portable lighting or spotlighting applications where narrowly focused beam intensity and distance are priorities, maiden is better advised. Consider both metrics plus beam particulars to make an informed choice rather than assuming higher numbers automatically mean better performance.

Common Questions on Candlepower vs Lumens

Q: If one candlepower equals around 12 lumens, doesn’t that make them basically equivalent?

A: Not quite! The cause of that conversion ratio is that candlepower describes intensity looking along one direction of a beam, while lumens encompass all light emitted across a sphere. So one candlepower is focused into ~1/12th of a sphere, yielding ~12 lumens worth when totaled. But intensity and total volume differ substantially.

Think of lumens like total rainfall and candlepower like peak rainfall rate. 100 inches of rain with 30 mph max rainfall rate will flood more than 5 inches at 120 mph peak rate, despite the latter having 4X higher peak candlepower.

Q: For flashlights and headlamps, is it better to have higher candlepower or more lumens?

A: It depends if you value intensity or runtime. More lumens generally require bigger batteries that add weight, but provide longer operation per charge. Higher candlepower packs more punch upfront, at the expense of faster battery drain.

Consider your target use – shorter backpacking trips may benefit from candlepower to travel lighter while maximizing immediate visibility. Longer camping multi-day usage favors lumens to reduce battery replacement frequency. Strike an appropriate balance of intensity vs runtime for your needs.

Q: Can I install extremely high candlepower and lumens aftermarket headlights on my truck?

A: Exercise caution here – street legality often limits headlight brightness. Installing ultra-high performance off-road lights can produce excessive glare blinding oncoming traffic when improperly used on streets. Check your State‘s regulations before upgrading headlamps.

Additionally, recognize that aux lights should supplement rather than replace your built-in headlights for road travel. Ensure a proper install positioning aux lights down and away from eyes instead of simply maximizing peak intensity.

Q: Why do some higher lumen light bulbs appear dimmer than lower lumen bulbs?

A: Likely because those higher lumen bulbs skew toward cooler color temperatures (6000K+). While emitting more total light, the bluer tones seem less intense to our eyes than warmer 2700K bulbs rated for fewer lumens.

Also, if comparing bulbs with vastly different beam spreads, narrowly directed beams often feel subjectively sharper than gently flood bulbs – even when the latter have higher measured lumen values.

Key Takeaways on Candlepower vs Lumens

• Candlepower defines intensity of light in one direction, while lumens describe total light output across all directions.

• Converting between the units is straightforward math, but intensity and total light volume differ substantially

• For directed lighting like flashlights, higher candlepower prioritizes peak beam intensity

• For ambient lighting like ceiling fixtures, higher lumens enable uniformly brighter spaces

• Consider beam pattern, distance, color temperature, and runtime along with raw candlepower/lumen ratings

So in essence:

• Candlepower = light drill putting force on one spot
• Lumens = number of ping pong balls emitted

Hopefully this guide has helped explain what candlepower and lumens are, how to convert between them, when to pay attention to each, and how to put the numbers into proper context when evaluating different lighting instruments. Let the light shine!