Home Improvement
LED Replacement Savings Calculator
Enter old and LED wattage, hours and electricity rate to see yearly savings.
How much does switching to LED save?
LED (light-emitting diode) lamps use far less electrical power than older incandescent or halogen bulbs for similar brightness, so the money is in watts × hours × your unit rate. Enter the old wattage, the LED wattage you will fit, hours of use per day, electricity price per kilowatt-hour (kWh) and how many bulbs you are swapping. Annual energy is watts ÷ 1,000 × hours/day × 365 × bulb count; cost is that kilowatt-hour figure times your rate; saving is old cost minus LED cost. Payback on the bulb purchase is often months, but purchase price is not deducted unless you do that offline. For other household running costs see the appliance running cost calculator.
Worked example
Four 60 W bulbs versus four 9 W LEDs at 3 hours/day and £0.28/kWh: old use ≈ 262.8 kWh/year (£73.58), LED ≈ 39.4 kWh (£11.04), saving ≈ £62.55/year.
Limits and assumptions
Ignores bulb purchase price, dimmer compatibility, warm-up behaviour and time-of-use tariffs unless you enter a blended rate.
Frequently asked questions
What does LED stand for?
Light-emitting diode — a semiconductor lamp that produces light efficiently with low heat loss compared with incandescent filaments.
Should I match lumens or watts?
Match brightness by lumens on the pack. Enter the wattage of the lamps you will actually leave switched on for the cost maths.
How do dual-rate tariffs work here?
Use a weighted average pence-per-kWh across day and night, or run the tool twice with each rate and typical hours.
Do dimmers change the saving?
Compatible LED loads still draw near their rated watts at full brightness; deep dimming uses less, but this page assumes the wattage you enter.