Do you know how much lumens of light you need for your room?
For household lighting, 15 lm/ft2 is more than enough.
For offices, use 30 lm/ft2.
For factories, use 50 lm/ft2.
Once you know the number of lumens you need, just divide that by the number of lumens a bulb or fixture provides, to understand how many bulbs or fixtures you need.
LED bulbs have become so cheap now, and there efficiency is increasing day by day. So, now it's a no brainer to use LEDs to save the most money in your homes, offices and factories.
If you don't believe me, look at the comparison below...