How required Lumens are calculated for a room?

The Lumen level or the brightness level in a room differs from a person to person. Some like dim level of light in living room and brighter in family room, kitchen or office. Brighter levels are always required and welcomed in the areas of work like kitchen. Calculating the amount of light you want in a particular area is not a difficult task once you have a clear requirement in your mind.

lumensTo start with, calculate the area of the room in sq feet.
For example we consider a room of 15 feet x 20 feet. The area of this room is 300 sq feet.   

Lighting experts recommend 40 to 60 Lumen per sq feet for a moderate lighting in a room.
We opt for 50 Lumen per feet. 

Multiply the room area by the Lumens desired by you.
Total desired Lumen in our room is (300×50) 15000 Lm. 

Select the lights (CFL, LED, Bulbs) you want to put up in the room and check the rating in Lumen for each one.
If your select MORIC A2528 12W LED fixture, it gives out roughly 1200 Lm. So you may have to put 13-14 such fixtures to properly lit up the room to your desired level.

This is just an approximate calculation. There are many other factors to consider like the colour of walls, floor and furniture which help to reflect the light back and make room look brighter. Height of the roof and position of the mounted lights are also major factors to be considered while planning the lighting for any room.

Side note: To convert Lux to Lumen, multiply Lux by 10.76

Jagdip Singh

I am Jagdip Singh, extremely fond of anything that is related to lighting, both designing and inner technicalities. When I am not working at my lighting showroom here at Chandigarh, I love to dig further into the world of lighting and share whatever little I know. This is where I post my ideas, experiments and experience.

Drop me a line anytime, whether it is about your lighting requirements, project, business or just a feedback. I’d love to hear from you.

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14 Responses

  1. Gautam Sep 04, 2013 - Reply

    Thanks a lot Jagdip!. I am an architect and this information will be really handy while calculating the number of lights in a room.

    I have seen many lights and fixtures in the market and they do not put the lumen details on it. Your formula and calculation is of no use if we do not have the details of the lumen given out by the light which we want to opt.

    Any suggestions?

    • Jagdip Singh Sep 04, 2013 - Reply

      Excellent point Gautam!

      The branded products like Philips LED, Philips Tube fittings etc., all have the lumen specification on it. Yes, I do agree that most of the products do not carry this important and critical (for architects and designers) information. Since you are an architect and light selection is your routine job, the best way out is to carry your own lumen meter with you when you go out for the selection of the light fixtures. Many cheap and handy lumen meters are available in the market.

      You can also demand the test report from the dealer or the manufacturer which normally carries full details like lumen, CRI, input watts etc.

      I hope this will help you with your query. Thanks for visiting and posting on my blog.

  2. Antonietta Follin Oct 01, 2013 - Reply

    I simply want to tell you that I am very new to weblog and seriously enjoyed you’re web page. Very likely I’m planning to bookmark your blog post . You really come with very good posts. Thanks a bunch for putting this knowledge for us.

    • Jagdip Singh Oct 01, 2013 - Reply

      Thanks Antonietta! Do visit again for more posts.

  3. Yogesh Puri Nov 18, 2013 - Reply

    Dear Jagdip

    I have a small office of about 500 sft. I am planing to put 16 of 16w LED would it suffice, ceiling height is about 9ft colour of walls, ceiling and floor is almost white and furniture is dark brown

    Please advice

    • Jagdip Singh Nov 19, 2013 - Reply

      Yogesh, 60lm per sq feet is good for office lighting. You can go for a 1800lm downlights (A good brand LED light of 18W can give out this much lumen). If you put 16Pc of 18W LED downlight which is capable of giving out 1800lm each will do a fine job. I do not think 16W will be able to give out effective 1800lm.

  4. Shobha Kumar Mar 05, 2014 - Reply

    Hi Jagdip
    can you please help me in deciding the LED light requirements for my apartment. I have fixed false ceiling for 3 bedrooms and also the living and dining areas. I want you to help me decide the watts required for each room. I can send you the measurements.

    I see that you are very enthusiastic about lighting and related topics. I did read the article on light calculation but i think I am lost.
    Regards
    Shobha Kumar.

    • Jagdip Singh Mar 05, 2014 - Reply

      Hello, Thanks a lot for your visit to my blog. Please do send me the measurements by email. Ceiling drawings will be better if you have put some design up there. I will surely try and help you out with this calculation and it will be a pleasure to help you.

      • Shobha Kumar Mar 05, 2014 - Reply

        Thanks Jagdip. I am sending the mail to mail@xxxxxx.com. Is that right?

        • Jagdip Singh Mar 05, 2014 -

          Yes, it is correct. (I have masked it to protect it from spam harvesters).

  5. Joe Xavier Sep 22, 2014 - Reply

    Sir, i wanted to know how much the height of the room affects the requirement.

    • Jagdip Singh Sep 27, 2014 - Reply

      The height of the room does effects the lux level of the light in the room. As a matter of fact many other things effect the lux level like the color of your walls, curtains, furniture, flooring.

      If you have light colors on your walls, ceiling and floor then lesser lumin can be used to achieve the desired lux level. All normal calculations are done keeping the height of the ceiling as 10 to 11 feet in mind.

      • Rajani Kumar Oct 13, 2014 - Reply

        “Normal calculations are done keeping the height of the ceiling as 10 to 11 feet in mind”. Nice, but, If I want to put an LED at a height of 20-22ft (Like in petrol bunk canopy), then, whether the LUX will be reduced up to 50%? (Because, now the height of the roof is doubled). If this is not the right way to calculate pls tell me if any formula will be there, which includes all the parameters like, Height, Length, width, LUX etc..Thanks in advance

        • Jagdip Singh Oct 26, 2014 -

          You are correct, the LUX level will reduce with the height of the light source. The calculation given here is approximate keeping the height of the light source at 10-12 feet.

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