Will switching to LED lightbulbs make a significant difference in my electric bill?
Say your electrical bill is $100 a month.  

Now say you have a refrigerator, a computer, a window fan and your light bulbs in your house as your only electrical devices.  Everything but your light bulbs are on 24/7.


Fridge: 725W **NOTE MOST FRIDGES DON'T ACTUALLY RUN 24/7 THIS IS JUST FOR EXAMPLE PURPOSES*
Computer : 125W
Fan: 150W
Lights (on 8 hours a day, 100W)





Fridge, computer and fan on all day = 1000W * 24h = 24kWh 
Lights on 8h a day = 0.8kWh
Total daily usage = 24.8kWh




In that scenario your lights represent 0.8/24.8 or 3% of your daily electrical consumption.

If you replace your light with a 15W bulb, you've dropped from 24.8kWh to 24.12kWh a day, a savings of only 2.7% of your total daily consumption.



Addendum:  I am not saying lighting is going to be 3% of your bill - I'm only making an example.  You have to do the math - you have to figure out how much total power you're using (check electric bill) and then how much power your lights use (look at the bulbs and measure how long each one is left on each day) and that's your total % of energy for lighting.  If that % is 15 then you can only reduce that 15%.  You can cut your lighting costs in half, but half of 15% is only 7.5%.