Turn old bulbs into measurable monthly savings fast. Enter your usage and rates for clarity. See payback, cash flow, and greener comfort every year.
| Example input | Value | Example output | Value |
|---|---|---|---|
| Bulbs | 20 | Annual kWh saved | ~1,489.60 |
| Old vs LED wattage | 60W → 9W | Year 1 energy savings | ~$238.34 |
| Usage | 4 hours/day, 365 days | Simple payback | ~1–2 years |
| Rate | $0.16/kWh | NPV (5 years, 0% discount) | Positive in many cases |
Lighting energy is driven by wattage, run time, and bulb count. A 60‑watt lamp used four hours daily consumes about 87.6 kWh yearly. Swapping to a 9‑watt LED drops that to roughly 13.1 kWh. Across twenty bulbs, the annual reduction is near 1,489.6 kWh, which is a meaningful load cut for most homes and small offices.
Electricity prices convert kWh into dollars. At $0.16 per kWh, saving 1,489.6 kWh equals about $238 in year‑one energy savings. If your blended rate is $0.10, the same reduction is about $149. If your rate is $0.25, savings rise to about $372. This sensitivity is why the calculator asks for your exact tariff.
Rated lifespans influence replacement spending and downtime. A 1,000‑hour incandescent may require several replacements over a multi‑year horizon, while a 15,000‑hour LED can run many years with minimal changes. When bulbs are hard to access, fewer replacements can also reduce labor time and disruption, which the install‑cost field can approximate.
Upfront cost is typically LED purchase price plus any installation, minus rebates. Simple payback is reached when cumulative yearly savings exceed that upfront amount. Over five to ten years, escalating electricity prices can increase the savings stream, while discounting can translate future savings into present‑value terms through NPV. Small upgrades often deliver reliable savings with low risk.
Use the year‑by‑year table to validate assumptions and spot break‑even timing. Compare old versus LED total costs to see whether savings come primarily from energy or from avoided replacements. For budgeting, focus on total savings, NPV, and payback together, and consider updating inputs when rates, hours, or bulb prices change.
Q: Does the calculator include bulb replacement costs?
Yes. It estimates replacements from total operating hours and each bulb’s rated lifespan, then spreads that cost across the analysis period to keep yearly totals readable.
Q: What if my LED is brighter or dimmer than the old bulb?
Match by lumens, not watts. If the LED is brighter than needed, choose a lower‑watt model or reduce bulb count to reflect the same light level.
Q: How are rebates handled?
Rebates reduce the upfront cost. Enter utility incentives, coupons, or bulk discounts as a total amount so payback and NPV reflect your net out‑of‑pocket expense.
Q: Why is there an electricity escalation rate?
Rates often change over time. Escalation increases projected energy and replacement costs each year, so long‑term savings can be higher than year‑one savings.
Q: What does NPV tell me here?
NPV converts future yearly savings into today’s dollars using your discount rate, then subtracts upfront cost. A positive NPV means the upgrade creates value at that discount rate.
Q: Can I use this for commercial facilities?
Yes. Increase bulb count and hours/day to match your site. For large buildings, consider segmenting by bulb type or zone and running separate scenarios for higher accuracy.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.