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Electrical

LED Savings Calculator

Annual savings and payback on an LED retrofit.

Your measurementsEvery assumption editable01
SavingsCalculated live02

Result

$297.84per year

Pays back in 3.2 months

Wattage saved20 lamps × 51 W
1020 W
Annual energy saved
1861.5 kWh
Annual cost saved
$297.84
Upfront cost20 × $4
$80
Payback0.27 years
3.2 months
Ten-year net savingafter the upfront cost
$2898.4

Lamp replacement cost is excluded from the saving and it favors LED considerably. An incandescent lasting a thousand hours against an LED lasting twenty-five thousand means twenty-five replacements avoided, plus the labor of changing them — which in a commercial setting often exceeds the energy saving.

In a cooled building LEDs save twice: less heat produced means less air conditioning to remove it. In a heated building the reverse applies slightly, since waste heat from lamps was doing some of the heating.

Match lumens rather than wattage when replacing. A 9 W LED replacing a 60 W incandescent is only a fair swap if it actually delivers around 800 lumens.

Wattage saved times hours times rate, with the upfront lamp cost divided back out. Lamp replacement savings are deliberately excluded, which makes the result conservative — the real case for LED is better than this shows.

Why use this tool?What it does differently03

Why use this tool?

Payback in months

Because for lighting retrofits it is usually months, not years.

Ten-year net

After the upfront cost, which is the figure that makes the decision.

Deliberately conservative

Avoided lamp replacements and reduced cooling load are both excluded.

Match lumens, not watts

A 9 W LED only replaces a 60 W bulb if it actually delivers the light.

How this worksThe method04

How this led savings calculator works

Wattage saved per lamp times the quantity gives total watts saved. Multiplied by hours per day and 365, divided by a thousand, gives annual kilowatt-hours; times your rate gives the money.

Payback divides the upfront lamp cost by that annual saving. For lighting used several hours a day it is typically a few months, which is unusually fast for any efficiency measure.

Two real benefits are left out, both favoring LED. An incandescent lasting a thousand hours against an LED lasting twenty-five thousand means many replacements avoided — and in a commercial setting the labor of changing them often exceeds the energy saving. In a cooled building, less waste heat also means less air conditioning.

How to use itStep by step05

How to use it

  1. Step 1: Compare like for like

    Match lumens between old and new, not wattage.

  2. Step 2: Count the lamps

    The retrofit only pays across the whole set.

  3. Step 3: Be honest about hours

    A lamp used twenty minutes a day pays back very slowly regardless of the saving per hour.

  4. Step 4: Prioritise by hours

    Retrofit the longest-running lamps first — that is where the money is.

Example usageWorked figures06

Example usage

A house retrofit
Twenty 60 W lamps replaced with 9 W LEDs, 5 hours a day at 16¢: 1,020 W saved, 1,861 kWh a year, $297.84 saved. At $4 a lamp that pays back in 3.2 months.
Over ten years
The same retrofit nets $2,898 after the $80 of lamps — and that excludes the incandescent replacements you would have bought.
Low-use lamps
The same lamps used 30 minutes a day save only $29.78 a year and take 32 months to pay back. Hours drive this more than wattage.
Frequently asked questionsCommon questions07

Frequently asked questions

How much does switching to LED save?

Replacing twenty 60 W lamps with 9 W LEDs running five hours a day saves around $298 a year at 16¢ per kWh, paying back the lamps in about three months.

How long do LEDs take to pay back?

For lamps used several hours a day, typically a few months. For rarely used lamps it can be years, which is why it is worth retrofitting the longest-running fixtures first.

Does this include the cost of replacing bulbs?

No, deliberately — which makes the result conservative. An LED lasting 25,000 hours avoids many incandescent replacements, and the labor of changing them often exceeds the energy saving.

Do LEDs save on air conditioning too?

In a cooled building, yes. Less waste heat means less cooling load. In a heated building the effect reverses slightly, since lamp heat was doing some of the heating.

How do I choose an equivalent LED?

Match lumens rather than watts. A 60 W incandescent is roughly 800 lumens, so any LED delivering that is a fair swap regardless of its wattage.

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