Rex says
Everyday utility math — the kind you'd otherwise pull up four browser tabs for. I keep it to one clean answer.
Try a scenario
Click to load — tweak from there.Inputs
Result
Annual savings
$316.46
Payback period (months)
2.7
Monthly savings
$26.37
10-year net savings
$3,094.55
kWh saved per year
1862
Upfront bulb cost
$70.00
Psst — share this and help Rex grow
One click, a permanent link with your numbers baked in.
How to use this
- 1Enter number of bulbs.
- 2Enter old bulb wattage (W).
- 3Enter led wattage (W).
- 4Enter hours on per day.
- 5Enter electricity rate ($/kWh).
- 6Enter cost per led bulb ($).
- 7Read your annual savings on the right — it updates as you type.
- 8Hit Share to keep the scenario or send it to someone.
About this calculator
An LED producing the same light as a 60 W incandescent draws about 9 W. Across a whole house the swap usually pays for itself inside a year and then keeps paying.
Worked example
Using the values the calculator loads with:
Inputs
- Number of bulbs: 20
- Old bulb wattage: 60 W
- LED wattage: 9 W
- Hours on per day: 5
- Electricity rate: 0.17 $/kWh
- Cost per LED bulb: 3.5 $
Results
- Annual savings: $316.46
- Payback period (months): 2.7
- Monthly savings: $26.37
- 10-year net savings: $3,094.55
- kWh saved per year: 1,862
- Upfront bulb cost: $70.00
What each field means
Inputs
- Number of bulbs
- The number of bulbs used in the calculation. Starts at 20 so you have a working example on load. Accepted range: 1–200.
- Old bulb wattage (W)
- The old bulb wattage used in the calculation, measured in W. Starts at 60 W so you have a working example on load.
- LED wattage (W)
- The led wattage used in the calculation, measured in W. Starts at 9 W so you have a working example on load.
- Hours on per day
- The hours on per day used in the calculation. Starts at 5 so you have a working example on load. Accepted range: 0–24.
- Electricity rate ($/kWh)
- The electricity rate used in the calculation, measured in $/kWh. Starts at 0.17 $/kWh so you have a working example on load. Accepted range: 0.01–1 $/kWh.
- Cost per LED bulb ($)
- The cost per led bulb used in the calculation, measured in $. Starts at 3.5 $ so you have a working example on load.
Results
- Annual savings
- Returned as a money amount in US dollars and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Payback period (months)
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Monthly savings
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- 10-year net savings
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- kWh saved per year
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Upfront bulb cost
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
How does the led vs incandescent savings calculator work?
An LED producing the same light as a 60 W incandescent draws about 9 W. Across a whole house the swap usually pays for itself inside a year and then keeps paying. The underlying maths is: Savings = (Old W − new W) ÷ 1,000 × hours × days × rate × bulbs.
What do I need to enter?
6 values: number of bulbs, old bulb wattage, led wattage, hours on per day, electricity rate, and cost per led bulb. Each field starts with a sensible default, so you can change one number at a time and watch the result move.
What does the annual savings result mean?
It is returned as a money amount in US dollars and updates live as you edit the inputs, so you can compare two or three versions of a scenario in a few seconds.
Is this calculator free, and do I need an account?
Yes, it's free, and no account is required. Nothing you type is stored on our servers — the maths runs entirely in your browser.
How accurate is the result?
It applies the standard formula exactly, so the arithmetic is precise. Estimates assume standard, average conditions — local rules, pricing, and materials vary.
Who is this tool for?
It's built for anyone doing everyday planning maths — a quick estimate that would otherwise need four browser tabs and a calculator app.
Accuracy and limitations
- Estimates assume standard, average conditions — local rules, pricing, and materials vary.
- Results are rounded for readability; add a buffer before ordering, booking, or committing.
- Double-check anything with a real cost attached against a local quote.
Related tools
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). LED Bulb Savings Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/led-savings
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/led-savings" target="_blank" rel="noopener">LED Bulb Savings Calculator — RevenueLab</a> (2026).</p>
Source: [LED Bulb Savings Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/led-savings) (2026).