LED Energy Savings

The  LED savings calculator  shows you how much  money you could save  by switching to  LED light bulbs . Simply input the details of your old, inefficient incandescent bulb, how much you use it, and the features of the LED bulbs you are thinking of buying.

LED Savings Over Regular Bulbs


What are LED light bulbs? - LED light bulb savings

Over the years, improvements in light bulb technology are such that they now produce less heat and more light as a proportion of their energy use. The latest and greatest technology is LED, which stands for Light-Emitting Diode. These are small electronic components that produce light when provided with an electric current. Each LED can only emit a small amount of light, so bulb manufacturers make a single bulb out of multiple LEDs. For the same amount of light output, LEDs use around 83% less energy than incandescent light bulbs.

Incandescent light bulbs blow because the tungsten filament burns out, due to all that heat. As LEDs run a lot cooler and employ more sophisticated semiconductor electronics, they can last from 15 to 40 times longer than incandescent light bulbs. That means you don't have to change them so often. This advantage is a significant factor to consider when looking at the price of LED bulbs. The replacement costs of incandescent bulbs can add up very quickly.

Calculating total LED light bulb cost (including replacement)

The total cost of a light fitting has two components. The cost of electricity the bulb uses and the cost of replacing the bulb when it expires. We can write down an equation that computes the total cost over a year by adding these two components together:

total cost = cost of electricity + cost of replacing


cost of electricity = (consumption / 1000) * (daily usage * 365.25) * energy price

cost of replacing = bulb price * ceil((daily usage * 365.25) / lifetime)


  • ceil() is a math function that rounds up to the next whole integer, and helps to calculate the number of bulbs;
  • daily usage is the number of hours per day, on average, the bulb is in use;
  • lifetime is the number of hours, on average, until the bulb expires;
  • consumption is the power consumption of the bulb, in Watts;
  • energy price is the cost of electricity per kilowatt-hour (kWh); and
  • 365.25 is the number of days, on average, in a year.

The part of the equation ceil((daily usage * 365.25) / lifetime) calculates how many bulbs will be required for a year. For an LED, this is likely to be one. Whereas if an incandescent bulb is left on all day, you could need a total of nine bulbs per year.

To calculate how long it will take before you starting saving money by using the more efficient, longer-lasting LED bulbs, we can simply do:

break-even point = (led total cost / incandescent total cost) * 12

Multiplying by 12 gives the break-even point in months.

How to use the LED savings calculator?

The basic idea is that you input the details of the LED bulb you are looking to buy, and that of your current incandescent light bulb. Then enter your electricity price, and how much you use that light. You can then compare the total costs and savings over several years, along with the break-even point, after which the LED bulb starts saving you money.

To make it a fair comparison, make sure the bulbs output similar amounts of light, usually stated in the bulb specifications in lumens or lux. For example, a 60 W incandescent bulb and a 10 W LED bulb output a light level of around 800 lumens, while a 100 W incandescent bulb outputs 1,600 lumens, which is the equivalent of a 16 W bulb. Learn more in our lux to lumen conversion calculator.

Let's now go through the process of using the LED savings calculator, step-by-step:

  1. Enter the price of the LED bulb you are thinking of buying;
  2. Input its power consumption in Watts (W);
  3. Check the expected lifetime of the LED bulb. The default is 15,000 hours, but it could be as much as 40,000 hours;
  4. Enter the same details for your current regular incandescent bulb;
  5. Input the electricity price you pay per kWh (or unit). You can find this information on your electricity bill;
  6. Estimate how long the light will be on each day (well, night more likely); and
  7. By default, the calculator will show you the total cost of each bulb, and the possible savings over one year. However, if you want to calculate these figures over a more extended period, change the value when asked: "Over how many years?".

You could also use this LED light bulb cost calculator to compare an LED bulb to other inefficient bulb types, such as halogen and compact fluorescent light (CFL) bulbs, so, you can also use it as an LED vs fluorescent energy savings calculator.

To help you with this, switch on the Advanced mode of the calculator, which allows you to select different high-energy bulb types. For each type, we use a typical value for the energy they consume and how long they last. If you are comparing a specific bulb, adjust these values accordingly to match it.