LED Savings Calculator: What Your Bulbs Really Cost
Lighting looks too small to matter, but it runs for hours every day in every room, and old bulbs waste most of their energy as heat. Swapping to LED typically cuts a bulb’s energy use by about 75–85% — and the saving multiplies by every bulb in the house. Enter your current bulbs below and this tool works as an LED savings calculator and an led light bulb cost calculator in one: it shows the energy and money you save each year, how fast the new bulbs pay for themselves, and what they save over their whole working life.
LED Savings Calculator
Enter the bulbs you have now and the LEDs that would replace them. Results update as you change inputs, or press Calculate. No sign-up and no email needed, just your numbers.
Enter your bulbs, then press Calculate to see your results.
Match the brightness, not the watts
Watts measure the energy a bulb uses, not the light it produces. That was a harmless shortcut when every bulb was the same technology, but it misleads today: an LED makes the same light for a fraction of the watts. Use the table to find the LED that matches your old bulb’s brightness, and check the lumens figure on the box before you buy.
| Old bulb | LED equivalent | Light output |
|---|---|---|
| 40 W incandescent | 5 W LED | 450 lumens |
| 60 W incandescent | 9 W LED | 800 lumens |
| 75 W incandescent | 12 W LED | 1,100 lumens |
| 100 W incandescent | 15 W LED | 1,600 lumens |
The rule is simple: shop by lumens, not watts. Decide how bright the old bulb was, pick the LED with the same lumens, and the watts take care of themselves. A bulb that is too dim is the main reason people go back to old stock, so match the brightness first and enjoy the saving second.
What about CFLs?
If your home still runs compact fluorescent (CFL) bulbs, the maths is less dramatic — and it is worth being honest about that. A 14 W CFL replaced by a 9 W LED saves only 5 W per bulb: worth having, but the payback takes far longer than swapping out a 60 W incandescent. The sensible order is to replace incandescents and halogens first, especially the bulbs used for the most hours each day, and let CFLs live out their lives, changing them to LED as they fail. You still gain instant full brightness and no mercury in the bin with every swap.
What to calculate next
Lighting sorted, these tools tackle the bigger loads in the house:
- Electricity Cost Calculator — what any appliance costs to run per hour, month and year.
- Solar Panel Calculator — how many panels your home needs and what they could save.
- Calculators hub — every free Wolveyes calculator in one place.
Frequently asked questions
How much do LED bulbs save?
About 75–85% of the energy of the incandescent bulbs they replace. A 9 W LED gives roughly the same light as a 60 W incandescent, so a home that swaps ten bulbs used five hours a day saves around 930 kWh a year.
Is it worth replacing CFLs with LEDs?
Eventually, but there is no rush. A CFL already uses far less energy than an incandescent, so the extra saving from LED is small. Replace CFLs as they fail, and put your money first into swapping any remaining incandescent or halogen bulbs.
How long do LED bulbs last?
Quality LED bulbs are rated for 15,000–25,000 hours. At five hours a day, a 25,000-hour bulb lasts about 13.7 years — which is why the lifetime saving in the calculator is so much larger than the yearly one.
What are lumens?
Lumens measure the actual light a bulb produces — its brightness. Watts only measure the energy it uses. As a guide, 800 lumens is about the light of an old 60 W bulb, and 450 lumens matches a 40 W bulb.
Estimates only — check the lumens and colour temperature (2700K is warm white) on the box.