How to use this calculator
LED savings depend on wattage difference, lamp count, and hours used. Compare bulbs with similar light output and suitability for dimmers or enclosed fixtures.
- Count bulbs with the same usage pattern.
- Enter old and replacement watts.
- Use average daily on-time and your rate.
FORMULA
The math behind the estimate
(old watts − LED watts) × bulbs × hours × 365 ÷ 1,000 × rate = annual savings.
Worked example
Replacing twenty 60 W bulbs with 9 W LEDs used three hours daily saves about 1,117 kWh and $201 a year at $0.18/kWh.
Change the defaults to model your home. The result is an estimate, not a guaranteed bill or savings promise.
How to read the result
Use the estimate to compare scenarios and find the inputs worth measuring more carefully. Utility bills can include fixed charges, taxes, delivery fees, minimums, tiers, and demand charges that are not fully represented by a simple energy rate.
Assumptions and limitations
- Replacement light output is comparable.
- Usage hours stay the same.
- Bulb purchase cost is excluded.
Climate, equipment condition, installation, controls, and household behavior can materially change results. Verify consequential installation and purchasing decisions with qualified providers.
Practical savings context
Prioritize high-use fixtures and check lumens, color temperature, dimmer compatibility, and enclosed-fixture ratings.
SOURCE
Data and methodology
Program information accessed August 2026. Geographic scope: United States. Last reviewed: August 6, 2026.
WattMeasure uses the source to frame the method and assumptions; your editable inputs determine the displayed result.
QUESTIONS
LED savings FAQ
How accurate is this LED lighting estimate?
It is a planning estimate based on the values you enter. Actual power draw, cycling, utility charges, climate, and equipment condition can change the result.
Should I use the default electricity rate?
Your own marginal or all-in supply rate is better. Check a recent bill or your utility's published rate schedule.
Does this include taxes and utility fees?
Only when they are reflected in the rate you enter. Fixed monthly charges are not included because they usually do not change with one appliance's usage.
Last reviewed August 6, 2026 · Data update policy