What should you know before buying LED Bulbs (Part:1)


  • The market of LED Lights is blooming very fast. Many companies serve LED Bulb to their customer and it is not easy for customer to choose best LED Bulb among them.
  • The customer does not aware the technical parameter of LED, so It becomes more difficult to find out the best quality of LED Bulbs.
  • With traditional incandescent light bulbs it was simple to get the right light bulb.  If a 60 watt bulb is the broke or fused you have just get another 60 watt. When it comes to LED lighting, it’s very different.  Since LED light bulbs doesn’t use the same amount of power that incandescent bulbs use.
  • LED is described in terms of incandescent equivalence so we may see an LED bulb described as a 60 watt equivalent when in reality it only uses about 9.5 watts. This is because LEDs are measured by lumens (the total amount of visible light put out by a light bulb).  There is not a direct mathematical comparison between the lumen ratings used in LEDs and the wattage consumed by an incandescent.
  • To choose best LED Bulbs we should consider following technical Parameters.

Parameters for Choosing LED Bulbs

 There are different factors to consider when choosing a suitable LED replacement bulb

Basic Technical Parameters:

  • Lumen (Lighting Intensity)
  • Watt (Power Consumption)
  • Correlated Color Temperature (Light color)
  • Color Rendering Index (CRI)
  • Beam angle (Spread of light)
  • Efficiency (Lumen / Watt)
  • Power Factor

Other Parameters:

  • Instant Light
  • Dimming capacity
  • LED Driver
  • LED Chip
  • Weight
  • Heating

 Basic Technical Parameter:

(1)  Lumen (Brightness):

  • When we deal with brightness of LED bulb, we must to know Lumens not Watts.
  • The amount of light emitted from a light bulb is measured in Lumens.
  • When we replace an incandescent or CFL bulb with an LED bulb we should confirm that LED bulb produces the same number of lumens that the old bulb did.
  • As a general benchmark, a standard 60-watt incandescent bulb, for example, produces about 800 lumens of light. By comparison, a CFL bulb produces that same 800 lumens using less than 15 watts
  • Do not use watts as a measure of brightness.
  • Lumens represent the amount of light emitted by a light source, and are a more accurate measure of the brightness of a bulb.
  • More lumens mean brighter light, fewer lumens mean dimmer light
  • 1 Foot Candle: 1 foot candle of light is the amount of light (Lumen) that generates one foot radius away from Lighting source so 1 Foot Candle= 1 Lumen / Sq.Foot
  • 1 Lux: 1 Lux of light is the amount of light (Lumen) that generates one Metert radius away from Lighting source so 1 Lux= 1 Lumen / Sq.Meter


  • It is meaningless if we compare lumens between an LED bulb and a CFL to an incandescent bulb. While we are measuring lumens, we also have to consider useful lumens.
  • LED gives directional light unlike incandescent, halogen or compact fluorescent bulbs that give out omni-directional light (or light all around the bulb).  If a light bulb emits light in every direction similarly over and beneath, then light that going up can get trapped in the light fitting and totally wasted.
  • 50% of light emitted from a CFL or incandescent bulb is trapped inside the fitting and never makes it out and reached to objects. This trapped light is just gets absorbed and wasted as heat.
  • The amount of lumens that actually reached at the objects of Room that bulb produces are called as the useful lumens.
Lumen Chart for Incandescent, CFL,LED
Wattage Lumens Useful Lumens
LED 9W 800 lm 800lm
CFL 20W 1000lm 500lm
Incandescent 60W 1000lm 500lm
  • There is no rule for how many Lumen is required.It will depend on room size and shape, height of ceilings, colour scheme, type of lamps & fitting.
Area Lumens/Sq Meter
Kitchen 300 to 400
Kitchen (Task) 700 to 800
Living Room 400 to 500
Hallway 300
Bedroom 300 to 400
Bedroom (Task) 700 to 800
Bathroom 500 to 600
Bathroom (Task) 700 to 800
Reading Area 400

 (2)  Watt (Power Consumption):

  • The amount of energy a light bulb consumed is indicated by Watt.
  • The watts refer to how much energy a bulb will use.
  • The lower the watts, the lower the electric bill. CFLs and LEDs have a lower wattage than incandescent bulbs, but emit the same light output
  • Watts measure power consumption, whereas lumens measure light actual brightness..
  • Wattage is no longer a reliable way to gauge a light bulb’s brightness.
  • In old days, when there was only one basic type of incandescent light bulb was available.consumers could buy the incandescent bulb on the term “watts” .
  • Incandescent lamps use the filament material heated to the same temperature, the only way to increase their light output is to increase the wattage. We actually feel difference in brightnes between 60 Watt, 100Watt or 150 Watt light bulbs incandescent bulb.
  • When new technology introduce The energy-saving CFL bulbs of 15 Watt CFL bulb produced the same light of a 60 Watt incandescent. A 25 Watt CFL was comparable to a 100 Watt incandescent in light output.
  • Generally LEDs produce the same amount of light as an incandescent bulb that has five to six times the wattage.
  • LED sources are much more efficient at converting watts to lumens. Different materials can be used within the LED sources with different light extraction efficacy so two different LED sources can consume the same number of watts but having different  lumen output.
Watt Approximate Lumens
25 Watt 230 to 270
35 Watt 250 to 410
40 Watt 440 to 460
50 Watt 330 to 450
60 Watt 800 to 850
75 Watt 1000 to 1100
100 Watt 1500 to 1600


Incandescent Watts CFL Watts LED Watts Lumens (Brightness)
40 8 – 12 4 – 5 450
60 13 – 18 6 – 8 750 – 900
75 – 100 18 – 22 9 – 13 1100 – 1300
100 23 – 30 16 – 20 1600 – 1800
150 30 – 55 25 – 28 2600 – 2800

About Jignesh.Parmar
Jignesh Parmar has completed M.Tech (Power System Control), B.E(Electrical) from Gujarat University. He has more than 13 years experience in Power Transmission-Power Distribution-Electrical energy theft detection-Electrical Maintenance-Electrical Projects(Planning-Designing-coordination-Execution). He is Presently associate with one of the leading business group as a Deputy Manager at Ahmedabad,India. He is Freelancer Programmer of Advance Excel and design useful Excel Sheets of Electrical Engineering as per IS,NEC,IEC,IEEE codes. He is technical Author for "Electrical Mirror" and "Electrical India" Magazines. He is Technical Blogger and Familiar with English, Hindi, Gujarati, French languages. He wants to Share his experience & knowledge and help technical enthusiasts to find suitable solutions and updating themselves on various Engineering Topics.

21 Responses to What should you know before buying LED Bulbs (Part:1)

  1. Raushan Singh says:

    Tell me about the exhaust fan/fan.. What is the paramater for decieding the better output,for better efficiency. On 1 Jul 2016 20:22, “Electrical Notes & Articles” wrote:

    > Jignesh.Parmar posted: “Introduction: The market of LED Lights is blooming > very fast. Many companies serve LED Bulb to their customer and it is not > easy for customer to choose best LED Bulb among them. The customer does not > aware the technical parameter of LED, so It becomes ” >

  2. vijay says:

    thnx sir its very usefull

  3. rajiv sharma says:

    sir can you please brief us on hvds system and AB cable


    Sir ,
    This is very useful information ,as well as i don”t know which parameter check for selecting LED bulbs. thanks

  5. Ashutosh says:

    Thanks very nice

  6. lalit bali says:

    hello Jignesh, this Aricle is very helpful and undei standing better about LED.

    can you please also suggest in long height induction light is better than led Light or not.

    waiting for reply.

  7. Mehmood Hassan says:

    A very useful link to lay man as well as to professional in national saving of energy prospective s.Keep it up. Best regards

  8. Anand Shekhar says:

    Dear Sir,

    Thank you for your article.

    I am doing LED Lighting design work for IOCL BARAUNI REFINERY and this is helpful for me.


  9. alex Udoka Ibude says:

    i am enjoying your lecture,thank you sir

  10. sadique says:

    useful information, thanks

  11. Muhammad kashif says:

    dear sir it’s very usefull knowledge about the electrical sir i want to know about colour rendering / temperature of light so that i select the light precisely.

  12. VIGNESH says:

    Thank you sir your posting new one today .it’s useful to select CFL & LED ext…

  13. surender poul says:

    Sir plz diff. Bw power tf and auto tf On 01-Jul-2016 8:22 pm, “Electrical Notes & Articles” wrote:

    > Jignesh.Parmar posted: “Introduction: The market of LED Lights is blooming > very fast. Many companies serve LED Bulb to their customer and it is not > easy for customer to choose best LED Bulb among them. The customer does not > aware the technical parameter of LED, so It becomes ” >

  14. Anil Jhummon says:

    Nice exercise. very informative. Thanks

  15. Desire Engineering Electrical Consultant says:

    Thanks a lot sir for all detail sending to us, I have my own design consultant so i need for data ,please share on my below mail id.

  16. manoj kumar says:

    thanqs sir!!! its really marvolus

  17. Darwin Crew says:

    LED lighting has opened up a number of impressive possibilities.

  18. Vishwanath Anand says:

    Plz Tell me Sir, what are rasons for fluctuation or more than rated current of neutral of 5 MVA 33/11KV Transformer.
    Thanking you.

  19. KJR says:


  20. jsridharan says:

    Thanks it is very informative

  21. RENJITHKUMAR says:

    Thanks sir very knowledgeable

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