What are the units of measurement of light?

Apart from Kilogram, Celsius, Liter, Watt, Calorie, etc. there are many other units of measurement unknown to a layperson, mainly because they are not used in our everyday life. Experts have fixed more than 125 clearly defined units. Half a dozen of them are only for measuring the intensity of light, including Candlepower and Lumen among many others.

First of all, though, let’s understand the unit called Foot-candle. One Foot-candle of light is the amount of light that a birthday cake candle generates one foot away. If you say you have a lamp that produces 100 Foot-candles of light, that means at one foot from the lamp, you will receive the amount of light equivalent to that of 100 birthday candles.

A lumen is a unit of measuring light that we might have heard of when buying flashlights or other forms of LED lights. It measures light much the same way as Foot-Candle. Remember, Foot-candle is how bright the light is one foot away from the source. Lumen is a way of measuring how much light gets to what you want to light! Lumen is equal to one Foot-candle falling on one square foot of area. You can better understand this by taking your candle and ruler, and placing a book at the opposite end of the candle. You will have a bit of light if you put the book right next to the candle. If that book happens to be one foot by one foot, it is one square foot. Now, all the light falling on that book, one foot away from your candle equals both, 1 Foot-candle and one Lumen!

Candlepower is a way of measuring how much light is produced by a light bulb. Years ago, Britain gave a definition that the light emitted by a 7/8 inch-thick candle made of sperm whale’s pure wax is equal to 1 Candlepower. Afterward, America gave a new unit called Candela, which is not much different from Candlepower. Nowadays, the term Candela is used instead of Candlepower.

Candlepower, or Candela, is a measure of how much light the bulb produces. It’s measured at the bulb, rather than how much falls upon the thing you want to light up. The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540 × 1012 hertz and that has a radiant intensity in that direction of 1/683 watt per steradian.

In short, Candlepower is a rating of light output at the source, using English measurements. Foot-candles are a measurement of light at an illuminated object. Lumen is a metric equivalent to Foot-candle in that it is measured at an object you want to illuminate. Divide the number of Lumens you have produced, or are capable of producing, by 12.57 and you get the Candlepower equivalent of that light source.

We use light for just about every task in our lives, so it’s always good to have some backup sources. The flashlights below might come in handy in case of a power outage or while camping:

Where to Buy
Energizer LED Flashlights
Etekcity 4 Pack LED Camping Lantern
SLONIK 1000 Lumen Rechargeable


1. Energizer LED Flashlights

These flashlights come with a thousand lumens of light and are water-resistant to boot. This means that they’ll be a great option for taking on a camping or hiking trip. The power source is also convenient, as you have a choice between using AA batteries and charging the flashlight through a USB cable. The material is aircraft-grade, so we can be confident that it won’t break or bend easily even with rough usage.

2. Etekcity 4 Pack LED Camping Lantern

A lantern might be more useful when you’re camping, as it can spread more light and illuminate the whole campsite if needed. This particular model could also be included in emergency kits in case of power outages, hurricanes, etc. It’s a collapsible version that won’t take up much space in any backpack.

3. SLONIK 1000 Lumen Rechargeable

This headlamp is a hands-free option for getting that necessary light while you’re camping, hiking, or need to work on something in a dark space. It would probably come in handy if you have to fix the pipes in the basement or search for something after dark while camping.

This item is also dustproof and waterproof, which makes it good for using out of doors. The lamp itself is an upgraded and woeful one that can reflect a 600-foot beam with a thousand lumens of light.

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