Calculate the electricity used by several LED bulbs and compare it with the lamps they replace.
We compare the monthly consumption of all LED bulbs with the previous lamps using the same hours and electricity price.
Watts measure power use; lumens measure light output. A fair comparison needs similar brightness.
A rarely used hallway saves less money than lighting that runs for many hours every day.
Replacing a 60 W lamp with a 9 W LED only makes sense as a direct comparison if both provide a similar useful amount of light. Watts measure electricity demand; lumens describe light output.
A lamp used for ten minutes a day saves very little money even with a large wattage reduction. Lighting that runs for several hours every day creates a much larger annual difference, which is why the calculator asks for daily operating time.
Before replacing many lamps, also check colour temperature, colour rendering, beam angle and dimmer compatibility. Lower electricity use is useful only if the room still has the brightness and light quality you need.
For room-level planning, read lux and room lighting. For consumption-focused advice, see how to reduce LED lighting consumption or compare LED vs halogen.
Editorial review: 11 Oct 2026. Compare lamps with similar lumens when estimating like-for-like savings.
