Enter the old bulb's wattage, the LED wattage, the hours on per day, the number of bulbs and the electricity price per kilowatt-hour. Typical replacements: a 60 watt incandescent is equal to a 9 watt LED, a 75 watt to about 11 and a 100 watt to about 15. Count the bulbs that are on for a meaningful time, since the savings come from hours of use.
LED Bulb Savings: worked example
| Old bulb wattage | 60 |
|---|---|
| LED bulb wattage | 9 |
| Hours on per day | 3 |
| Number of bulbs | 20 |
| Electricity price per kWh | $0.17 |
| Savings per year | $190 |
| Energy saved per year (kWh) | 1,116.9 |
LED Bulb Savings: changing Electricity price per kWh
| Electricity price per kWh | Savings per year | Energy saved per year (kWh) |
|---|---|---|
| $0.14 | $156 | 1,116.9 |
| $0.15 | $168 | 1,116.9 |
| $0.17 (example) | $190 | 1,116.9 |
| $0.19 | $212 | 1,116.9 |
| $0.20 | $223 | 1,116.9 |
LED Bulb Savings: compare input ranges
| Input | Tested from | To | Savings per year: low input | Savings per year: high input | Swing |
|---|---|---|---|---|---|
| Electricity price per kWh | $0.15 | $0.19 | $168 | $212 | $45 (24%) |
| Old bulb wattage | 54 | 66 | $168 | $212 | $45 (24%) |
| Hours on per day | 2.7 | 3.3 | $171 | $209 | $38 (20%) |
| Number of bulbs | 18 | 22 | $171 | $209 | $38 (20%) |
| LED bulb wattage | 8 | 10 | $194 | $186 | $7.45 (3.9%) |
LED Bulb Savings: individual input comparisons
| Input | Value | Savings per year | Energy saved per year (kWh) |
|---|---|---|---|
| Old bulb wattage | 48 | $145 | 854.1 |
| 54 | $168 | 985.5 | |
| 60 | $190 | 1,116.9 | |
| 66 | $212 | 1,248.3 | |
| 72 | $235 | 1,379.7 | |
| LED bulb wattage | 7 | $197 | 1,160.7 |
| 8 | $194 | 1,138.8 | |
| 9 | $190 | 1,116.9 | |
| 10 | $186 | 1,095 | |
| 11 | $182 | 1,073.1 | |
| Hours on per day | 2.4 | $152 | 893.5 |
| 2.7 | $171 | 1,005.2 | |
| 3 | $190 | 1,116.9 | |
| 3.3 | $209 | 1,228.6 | |
| 3.6 | $228 | 1,340.3 | |
| Number of bulbs | 16 | $152 | 893.5 |
| 18 | $171 | 1,005.2 | |
| 20 | $190 | 1,116.9 | |
| 22 | $209 | 1,228.6 | |
| 24 | $228 | 1,340.3 | |
| Electricity price per kWh | $0.14 | $156 | 1,116.9 |
| $0.15 | $168 | 1,116.9 | |
| $0.17 | $190 | 1,116.9 | |
| $0.19 | $212 | 1,116.9 | |
| $0.20 | $223 | 1,116.9 |
LED Bulb Savings: combined input changes
| Electricity price per kWh / Old bulb wattage | 48 | 60 | 72 |
|---|---|---|---|
| $0.14 | $120 | $156 | $193 |
| $0.15 | $128 | $168 | $207 |
| $0.17 | $145 | $190 | $235 |
| $0.19 | $162 | $212 | $262 |
| $0.20 | $171 | $223 | $276 |
LED Bulb Savings: which assumptions move the result?
LED Bulb Savings: values and definitions
| Quantity and definition | Value used |
|---|---|
| Old bulb wattage | 60 |
| LED bulb wattage | 9 |
| Hours on per day | 3 |
| Number of bulbs | 20 |
| Electricity price per kWh | $0.17 |
| Savings per year | $190 |
| Energy saved per year (kWh) | 1,116.9 |
LED Bulb Savings: half and double Electricity price per kWh
| Electricity price per kWh | Savings per year |
|---|---|
| $0.09 | $95 |
| $0.17 | $190 |
| $0.34 | $380 |
Heat from old bulbs offset heating in winter and added to cooling in summer, so the net effect is a bit smaller in cold climates. Dimmable and specialty bulbs cost more. Cheap LEDs can flicker or fail early.
Color temperature and brightness in lumens should match your needs, not the wattage.
LED Bulb Savings: formula
Common error: Assuming the savings apply to heating months in the same way. In a cold climate the old bulbs also gave off useful heat, which the furnace now has to supply.
Energy & Utilities calculators: Generator Size Calculator, Electricity Cost Calculator, EV Charging Cost Calculator, MPG Calculator, Battery Runtime Calculator, Solar Panel Output Calculator.
Bulbs save money in proportion to the hours they burn, so the same swap is worth far more in a kitchen than in a closet. Replacing twenty 60 watt bulbs with 9 watt LEDs that run three hours a day saves about 1,117 kilowatt-hours a year, or roughly $190 at 17 cents. The bulbs also last longer, which the electricity math does not count.
Use the hours each bulb really burns, not the hours the room is occupied. Lights left on in empty rooms count against you.
See other appliance costs on the electricity cost calculator, solar production on the solar panel output calculator and the return on the payback calculator. The generator and battery runtime pages relate to backup power, and the percent change calculator shows the reduction.
Does this result include bulb purchase cost?
No. Divide the actual extra purchase cost by applicable annual net savings for a simple cash-flow payback, with operating hours and tariffs held constant.
Can wattage alone establish equivalent light output?
No. Compare the actual lumen output and other needed lighting characteristics. A selected nine-watt input is not a promise of equivalence for every lamp.
How much does switching to LED bulbs save?
Savings come from the difference in entered watts, multiplied by operating hours and electricity price. An 80% or 90% reduction, or $9.50 per bulb per year, needs the corresponding inputs. Compare lamps delivering the intended light output and account separately for purchase and replacement costs.
How long do LED bulbs last?
Use the rated life on the actual lamp’s specification and its stated conditions. At an assumed three hours daily, 15,000 hours is about 13.7 years and 25,000 hours about 22.8 years. Those are conversions, not guaranteed service lives; the lower rating does not exceed fifteen years at that usage.
What wattage LED replaces a 60 watt bulb?
Compare the product’s lumens, not a fixed wattage substitution. An assumed 800-lumen lamp at 8 or 10 watts can illustrate an efficient replacement, but those values need the actual specification. Color, dimmer compatibility, beam pattern and fixture restrictions also affect whether the replacement suits the application.