Choosing LED Lights
A practical guide to understanding lumens, wattage, luminous efficacy, colour temperature, CRI, beam angle, IP protection, 3CCT and other essential LED lighting specifications for selecting the right product.
Six specifications tell you most of what you need to know about an LED light: lumens, luminous efficacy (lm/W), colour temperature (K), colour rendering (CRI), beam angle and IP rating. Wattage only shows power consumption, not the amount of light. Below I go through what each specification tells you and what to watch for when you compare two lights. You can also download the illustrated guide as a PDF.
Watts or lumens?
In LED lighting, watts and lumens describe two different things. Watts (W) indicate how much electrical power the lamp consumes. Lumens (lm), on the other hand, indicate the amount of light emitted.
- Watts (W)
- power consumption
- Lumens (lm)
- amount of light emitted
Why aren't watts enough?
With traditional bulbs, many people became accustomed to estimating brightness from wattage. With LEDs, this can be misleading because two lamps with the same wattage can produce different luminous flux. Always check the lumen value when comparing products.
If two lamps are both rated at 40W, but one produces 4,500lm and the other 5,650lm, the second provides more light at the same rated power. In the LEDsec range, for example, the LHB120-PRO linear light produces 5,650lm at 40W.
Pro tip:instead of asking first, “How many watts is it?”, ask how much light is needed in that location.
What does lm/W mean?
Luminous efficacy shows how many lumens of light a lamp produces per watt of power consumed. Its unit is lumens per watt (lm/W).
- Formula
- luminous efficacy = lumens ÷ watts
- Calculation example
- 4,500lm ÷ 40W = 112.5lm/W
The higher the lm/W value, the more light is produced per watt of power consumed. This is particularly important where operating hours are long, such as in shops, workshops, warehouses and industrial spaces.
lm/W isn't everything
High luminous efficacy alone does not mean that a lamp is better for every task. Light distribution, colour temperature, colour rendering, IP rating and the installation environment are equally important.
Pro tip:use lm/W to compare energy efficiency, but always make the final choice based on the application.
Colour temperature: 3000K, 4000K, 5000K, 6500K
Colour temperature, expressed in kelvins (K), describes how warm or cool white light appears.
- 3000K, warm white
- a warmer, more relaxing lighting atmosphere
- 4000K, neutral white
- common for general and task lighting
- 5000K, cooler white
- a functional, more focused effect
- 6500K, cool white
- a very cool, daylight-like appearance
What is 3CCT?
A 3CCT luminaire allows you to select from several, usually three, preset colour temperatures. This makes the same luminaire more flexible for use in different environments.
Pro tip:kelvin does not indicate brightness. Two lamps with the same lumen output can create a completely different atmosphere if their colour temperatures differ.
CRI/Ra: how natural do colours look?
CRI (Colour Rendering Index), also known as Ra, indicates how naturally a light source reproduces the colours of illuminated objects compared with a reference light source.
- CRI ≥80
- common for general lighting
- CRI ≥90
- better colour rendering where more accurate colour appearance is important
Where is it particularly important?
In shops, showrooms, clothing or product displays, and anywhere the colours of illuminated surfaces matter. In the LEDsec range, one example is the MATRIX24-S spotlight with CRI ≥90.
A higher CRI is not the same as greater brightness
CRI describes the quality of colour rendering; the amount of light is still indicated by lumens. Two lamps with similar luminous flux can therefore render colours differently.
Pro tip:when illuminating merchandise, material samples or coloured surfaces, don't look only at lumens and kelvins: check the CRI/Ra value as well.
Beam angle: where does the light go?
The beam angle indicates how widely a lamp's light spreads. With the same luminous flux, a narrower beam is more concentrated, while a wider beam distributes the light over a larger area.
- 24°
- more concentrated accent light
- 90°
- wider illumination
- 110–120°
- general light spread over a large area
A narrower beam can be useful for accent lighting or targeted light from a greater mounting height. A wider angle can be advantageous for general ambient lighting. The MATRIX24-S spotlight, for example, is available with a 15°, 24° or 36° beam angle.
Pro tip:don't compare lumen values alone. The beam angle determines how large an area receives the available light.
IP rating: what do IP20, IP44, IP54 and IP65 mean?
An IP code consists of two digits. The first indicates protection against solid foreign objects and dust; the second indicates protection against water ingress.
- IP20
- primarily for dry indoor environments
- IP44
- greater protection against splashing water
- IP54
- increased protection against dust and splashing water
- IP65
- dust-tight and protected against water jets
Always choose the IP rating to suit the actual installation environment. Outdoors, in dusty rooms or where moisture is present, it is especially important to check the product data sheet and installation instructions. The PROOF60 linkable LED light, for example, is rated IP65.
Pro tip:IP65 does not mean that the lamp can be submerged under all conditions. Always refer to the meaning of the specific IP rating and the manufacturer's instructions.
3CCT, dimming and sensors: three different functions
Modern LED luminaires often include several convenience or control functions. These should be considered separately because each controls a different property.
- 3CCT
- selection between several preset colour temperatures
- Dimmable
- brightness can be adjusted with suitable controls and compatible devices
- Sensor
- the lamp can switch or adjust automatically based on a sensor
The MATRIX24-S, for example, is 3CCT but not dimmable. The NIGHT-S wall staircase light switches on with a PIR motion sensor, and its colour temperature can also be selected.
Compatibility
When configuring a dimmable or sensor-controlled system, checking the luminaire's function alone may not be enough. The controller, dimmer, power supply or other connected equipment may also need to be compatible.
Pro tip:“3CCT”, “dimmable” and “sensor-controlled” are not synonyms. Before buying, check exactly which functions the product supports.
Recommended LEDsec lights
LHB120-PRO
1.2m linear light: 40W, 5,650lm, 3CCT switch, 110° beam angle.
View product
MATRIX24-S
16W, 1,600lm spotlight with CRI ≥90 colour rendering, 3CCT, 15°, 24° or 36°.
View product
PROOF60
IP65 linkable light, 0.6m: 20W, 2,240lm, 112lm/W, 4000K.
View product
NIGHT-S
Wall staircase light with PIR motion sensor (4m, 120°), 1.5W, 90lm, 3CCT.
View productQuick guide: what should you check when choosing an LED light?
The table below shows which technical specification answers each question.
| What would you like to know? | Check this specification |
|---|---|
| How much light does it produce? | lumens (lm) |
| How much power does it use? | power (W) |
| How efficient is it? | luminous efficacy (lm/W) |
| Is the light warm or cool? | colour temperature (K) |
| How natural do colours look? | CRI/Ra |
| How wide is the beam? | beam angle (°) |
| Is it suitable for the environment? | IP rating |
| Can the light colour be selected? | 3CCT |
| Can the brightness be adjusted? | dimmability |
| Can it switch on automatically? | sensor, detector |
When choosing the right LED light, don't look only at wattage. Lumens, lm/W, kelvins, CRI, beam angle and IP rating together show how suitable the lamp is for the task. When choosing a specific product, always check the current technical specifications and installation instructions on the product page or data sheet.
If you are not sure which light suits your room or project, write to us and we will help you choose.
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