BYTETOOLS

LED Savings Calculator

Compare old bulbs with LEDs on energy, cost and lifespan. See annual kWh, yearly saving, payback in months and how many replacement bulbs you avoid buying.

1,095
Old bulbs — kWh/year
164
LEDs — kWh/year
$186.15
Old bulbs — cost/year
$27.92
LEDs — cost/year
$158.23
Energy saving per year
3.0 months
Payback
13.7
LED life (years at this use)
372.3
CO₂ avoided per year (kg)
240.0
Replacement bulbs avoided
$360.00
Bulb cost avoided
$40.00
Cost to buy the LEDs
$2,487.50
Net saving over LED life

Annual energy = watts × hours per day × 365 ÷ 1,000 × bulb count, priced at your unit rate. Replacement bulbs avoided = (LED rated hours ÷ old bulb rated hours − 1) × bulb count, and payback = the cost of the LEDs ÷ the monthly energy saving. Rated lives are laboratory figures and real fittings run hotter, so treat the lifetime numbers as optimistic. Swapping heat-producing bulbs also slightly increases winter heating and reduces summer cooling, which is not modelled here.

What is the LED Savings Calculator?

The ByteTools LED Savings Calculator prices a lighting swap properly. Pick a common upgrade or type in your own wattages, say how many bulbs you have and how long they are on each day, and it works out annual kWh and cost for the old bulbs and the LEDs side by side at your electricity price.

  • Seven common bulb swaps as presets, with every field still editable
  • Annual kWh and cost for the old bulbs and the LEDs side by side
  • Replacement bulbs avoided over the LED's rated life, and what they cost
  • Payback in months, LED life in years at your actual usage
  • CO₂ avoided per year at an editable grid carbon intensity
  • All arithmetic runs locally in your browser — nothing is uploaded

How to use the LED Savings Calculator

  1. 1

    Pick a common swap from the dropdown — such as 60 W incandescent to 9 W LED — or type your own wattages.

  2. 2

    Enter how many bulbs you are changing and how many hours a day they are switched on.

  3. 3

    Set your electricity price per kWh and each bulb's rated life in hours.

  4. 4

    Add the price of an old bulb and the price of an LED so the calculator can cost the replacements you avoid.

  5. 5

    Read the annual kWh and cost for each option, the payback in months, and the net saving over the LED's life.

About the LED Savings Calculator

The ByteTools LED Savings Calculator prices a lighting swap properly. Pick a common upgrade or type in your own wattages, say how many bulbs you have and how long they are on each day, and it works out annual kWh and cost for the old bulbs and the LEDs side by side at your electricity price.

Beyond the energy line it handles the part most calculators skip: bulb replacements. Using each bulb's rated hours it works out how many old bulbs you would have bought over one LED's life, what that costs, how many years the LED lasts at your usage, and the net saving after the LEDs are paid for. Payback is shown in months.

Everything runs locally in your browser — no bills, no meter readings and no personal data leave your device. Rated lives on the box are laboratory figures and enclosed fittings run hotter than the test rig, so treat the lifetime numbers as an optimistic ceiling rather than a promise.

Frequently asked questions

How much money do LED bulbs actually save?

Swapping ten 60 W incandescent bulbs used five hours a day for 9 W LEDs cuts about 930 kWh a year. At 17 cents per kWh that is roughly 158 dollars a year, so the bulbs typically pay for themselves in under four months. Enter your own numbers above for your figure.

What LED wattage replaces a 60 watt bulb?

Around 8 to 10 watts gives the same 800 or so lumens as a 60 W incandescent. For a 100 W bulb look for 14 to 16 watts and about 1,600 lumens. Buy on lumens rather than watts — wattage only tells you what it costs to run.

How long do LED bulbs really last?

Boxes claim 15,000 to 50,000 hours, which at three hours a day is 14 to 45 years. Real fittings, especially enclosed or recessed ones, run hotter than the test conditions and shorten that considerably. The rated hours field is editable so you can model a more pessimistic figure.

Is it worth replacing bulbs that still work?

For anything used more than an hour or two a day, usually yes — the energy saving normally outruns the price of the bulb within months. For a closet light used a few minutes a week, the payback stretches into years and it makes more sense to wait until the bulb fails.

Do LED bulbs increase heating costs in winter?

Very slightly. An old incandescent bulb was mostly a small heater, so removing it does shift a little load onto your heating system in winter — and reduce it on air conditioning in summer. The effect is small and is not modelled here, so the annual saving shown is a touch optimistic in cold climates.

How do I calculate a bulb's energy use?

Energy in kWh = watts × hours per day × 365 ÷ 1,000, then multiply by the number of bulbs. Multiplying by your unit rate gives the annual cost. That is exactly the formula this calculator applies to both the old bulbs and the LEDs.

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