LED Savings Calculator: LED vs Incandescent Cost & Payback

Estimate LED bulb savings, kWh reduction, monthly cost, 10-year savings, and payback. Private by design: runs locally in your browser.

Inputs

Common bulb replacements

Currency Electricity price preset Brightness target

Number of bulbs Incandescent wattage (W) LED wattage (W)

Hours per day Days per year Electricity price (per kWh)

Enter pounds per kWh. 26.11 p/kWh = 0.2611 GBP/kWh.

Optional assumptionsCO2, bulb prices, and rated lifetimes

Grid intensity (kg CO₂/kWh) Optional LED price per bulb Incandescent price per bulb

LED lifetime (hours) Incandescent lifetime (hours)

Bulb prices and lifetimes power payback, replacement bulbs avoided, and lifetime net savings. Match the package label when you have it.

Awareness-level estimator. Real usage and prices vary by room, habits, and tariff. Edit to match your situation.

Results

How to Calculate LED Savings

The calculator compares the electricity used by your old incandescent bulbs with the electricity used by the LED replacements. It keeps kWh visible, but turns the result into the money questions most people need: monthly savings, annual savings, payback, 10-year savings, and lifetime net savings.

Choose a brightness target in lumens, then pick the incandescent and LED wattages that match your bulbs.
Enter how many bulbs are being replaced and how long they run.
Use a tariff preset or enter your own electricity price in currency units per kWh.
Add bulb prices and lifetimes if you want payback and lifetime net savings.

Variables

W_inc is the old incandescent watts, W_LED is the replacement LED watts, n is bulb count, h is hours per day, d is days per year, and p is electricity price per kWh.

Core formulas

kWh before = Winc x h x d x n / 1000
kWh after = WLED x h x d x n / 1000
kWh saved = kWh before - kWh after
Annual savings = kWh saved x p
Monthly savings = annual savings / 12

Payback and lifetime formulas

Percent reduction = kWh saved / kWh before x 100
LED purchase cost = LED bulb price x n
Payback years = LED purchase cost / net annual savings
Lifetime net = lifetime energy savings + avoided incandescent bulb cost - LED purchase cost

Worked example: one 60W incandescent replaced by a 9W LED for 3 hours per day saves (60 - 9) x 3 x 365 / 1000 = 55.8 kWh/year. At 26.11 p/kWh, that is about GBP 14.58 per year, or GBP 1.22 per month, before bulb replacement savings.

Assumptions and sources

Last reviewed: 30 June 2026. Defaults are estimates; your bill, taxes, fixture heat, and product quality can change the result.

U.S. Department of Energy LED lighting guidance: residential LEDs use much less energy than incandescent lighting and quality LEDs last much longer.
U.S. Department of Energy lumens guidance: common replacements are about 450, 800, 1100, and 1600 lumens for 40W, 60W, 75W, and 100W incandescent bulbs.
U.S. EIA Electric Power Monthly: U.S. residential average electricity price, April 2026.
Ofgem price cap unit rates: Great Britain direct debit electricity unit rate for 1 July to 30 September 2026.
Eurostat electricity price statistics: EU household electricity average for the second half of 2025.

Common LED Savings Examples

Examples use the Great Britain preset of 26.11 p/kWh. Change the calculator inputs for your own rate.

One 60W bulb

1 bulb, 60W to 9W LED, 3 hours/day, 365 days/year.

GBP 14.58/year saved, about GBP 1.22/month.

Ten household bulbs

10 bulbs, 60W to 9W LED, 3 hours/day, 365 days/year.

GBP 145.81/year saved, about GBP 12.15/month.

Outdoor lights overnight

2 bulbs, 60W to 9W LED, 10 hours/night, 365 nights/year.

GBP 97.21/year saved, about GBP 8.10/month.

Office or commercial case

80 bulbs, 60W to 9W LED, 10 hours/day, 260 workdays/year.

GBP 2,769.75/year saved, about GBP 230.81/month.

LED Buying Tips That Affect Savings

Choose brightness by lumens

Watts measure power, not brightness. For most household replacements, use about 450 lumens for 40W, 800 lumens for 60W, 1100 lumens for 75W, and 1600 lumens for 100W.

Check color temperature

Warm white bulbs around 2700K feel closest to incandescent light. 3000K is slightly crisper, while 4000K to 5000K is better for task areas where a cooler appearance is useful.

Look at CRI and labels

A CRI of 90+ helps colors look more natural. ENERGY STAR and Lighting Facts labels can help compare brightness, life, color, and estimated yearly energy cost.

Match the fixture

Use dimmable LEDs with LED-compatible dimmers. For sealed fixtures, outdoor lights, damp areas, or smart bulbs, check that the package explicitly supports that location and heat level.

Bulb Type Comparison

Typical values for about 800 lumens, used 3 hours per day at 26.11 p/kWh. Product labels vary.

Bulb type	Typical watts	Brightness	Lifespan	Annual running cost	Heat output	Replacement frequency
Incandescent	60W	About 800 lm	About 1,000 hours	GBP 17.15	Very high	About yearly at 3 h/day
Halogen	43W	About 800 lm	About 2,000 hours	GBP 12.29	High	Every 1-2 years
CFL	14W	About 800 lm	About 8,000-10,000 hours	GBP 4.00	Low to medium	Every 7-9 years
LED	9W	About 800 lm	About 15,000-25,000 hours	GBP 2.57	Low	Often 13+ years at 3 h/day

LED Savings FAQ

How much does a 60W bulb cost to run?

A 60W incandescent used 3 hours per day uses about 65.7 kWh per year. At 26.11 pence per kWh, that is about GBP 17 per year for one bulb.

How much can I save by switching to LED bulbs?

Savings depend on wattage, use hours, bulb count, and electricity price. Replacing ten 60W incandescent bulbs with 9W LEDs used 3 hours per day saves about 558 kWh and GBP 146 per year at 26.11 pence per kWh.

What LED replaces a 60W incandescent?

For similar brightness, look for about 800 lumens. Common 60W incandescent replacements are usually 8W to 10W LEDs, with 9W used as this calculator's default.

Do LEDs really last 25,000 hours?

Many quality LEDs are rated around 15,000 to 25,000 hours or more, but actual life depends on heat, fixture type, switching cycles, and product quality. Use the lifetime input to match the bulb package.

Should I replace CFLs too?

Replacing CFLs saves less electricity than replacing incandescent bulbs, but LEDs can still be worthwhile for better instant-on performance, dimmer compatibility, lower mercury concerns, and lower wattage. Compare the CFL wattage against the LED wattage in the calculator.

Are LEDs worth it if electricity is cheap?

Usually yes for frequently used bulbs, because LEDs use much less electricity and last longer. If your electricity price is low or the bulb is rarely used, the payback period will be longer.

5 Fun Facts about LED Swaps

Incandescents are mini heaters

Only about 5% of an incandescent’s power becomes visible light; the rest is heat. Fifteen 60 W bulbs dump roughly the same heat as an 800 W space heater.

Heat leak

LEDs shrug off flicking

Quality LEDs are rated for 25,000+ hours and tens of thousands of switch cycles, so pairing them with motion sensors or smart timers barely dents their lifespan.

Switch-happy

“Dim-to-warm” mimics sunsets

Some LEDs shift from 3000 K down to a candle-like ~2000 K as you dim them, recreating the cozy amber glow our brains link with evening wind-down.

Circadian cozy

Amber street LEDs calm insects

Field trials show warm-amber LEDs attracted ~50% fewer insects than cool-white fixtures, making them friendlier for pollinators and porch hangs alike.

Bug-friendly

One bulb, big carbon dent

Swapping a single 60 W bulb for a 9 W LED that runs 3 hours/day saves ~560 kWh over 10 years—about 220 kg of CO₂ on an average grid.

Carbon math