★ REFERENCE TABLE · HOME · ENERGY
Shop by lumens, not watts: a 60W incandescent gives about 800 lumens, and a 9W LED matches it. At 3 hours a day and $0.17 per kWh, that LED costs $1.68 a year against the incandescent's $11.17 — saving $9.49 per bulb per year, $37.97 for four bulbs, and $379.75 over ten years. The table below covers every common bulb size, and the calculator reruns the math for your hours, your rate, and your bulb count.
Pick the incandescent wattage you are replacing, enter how long the bulb burns each day, your electricity rate, and how many bulbs you are switching. The calculator finds the LED equivalent and prices both bulbs over a year and over ten years. The printed table underneath uses $0.17 per kWh and 3 hours a day; your numbers replace those assumptions the moment you change a field.
Yearly costs below use 3 hours a day at $0.17 per kWh. LED wattages are typical equivalents, not exact for every brand — check the lumens on the box, since that is what your eyes actually see. Use the print button above for a clean copy of this table.
| Incandescent | Lumens | LED equivalent | LED cost / yr | Incandescent cost / yr | Saving / yr |
|---|---|---|---|---|---|
| 40W | 450 | 6W | $1.12 | $7.45 | $6.33 |
| 60W | 800 | 9W | $1.68 | $11.17 | $9.49 |
| 75W | 1,100 | 13W | $2.42 | $13.96 | $11.54 |
| 100W | 1,600 | 18W | $3.35 | $18.62 | $15.26 |
| 150W | 2,600 | 24W | $4.47 | $27.92 | $23.45 |
Savings are computed from unrounded costs and then rounded for display, so a row's saving can differ by a cent from subtracting its two rounded costs. The pattern is the point: the bigger the old bulb and the longer it burns, the faster the LED pays.
Annual cost = watts ÷ 1,000 × hours per day × 365 × rate per kWh. Annual saving per bulb = incandescent cost − LED cost. Total annual saving = per-bulb saving × bulb count. Ten-year saving = total annual saving × 10, computed from the unrounded saving (so $37.97 a year over ten years is $379.75, not $379.70 — the unrounded $37.9746 a year is what gets multiplied). LED equivalents are the standard retail mappings: 40W → 450 lumens → about 6W; 60W → 800 → 9W; 75W → 1,100 → 13W; 100W → 1,600 → 18W; 150W → 2,600 → 24W. Treat LED watts as typical ranges — brands vary by a watt or two at the same lumens.
Setup: 60W incandescent, 3 hours/day, $0.17/kWh, 4 bulbs.
Line 1 — the match. 60W means about 800 lumens, matched by a 9W LED.
Line 2 — the LED cost. 9 ÷ 1,000 × 3 × 365 × $0.17 = $1.68 per bulb per year.
Line 3 — the old bulb's cost. 60 ÷ 1,000 × 3 × 365 × $0.17 = $11.17 per bulb per year.
Line 4 — the saving. $11.17 − $1.68 = $9.49 per bulb per year (from unrounded costs); × 4 bulbs = $37.97/yr; × 10 years = $379.75, before counting the incandescent bulbs you no longer buy.
A bright bulb, long hours, pricey power: 100W, 5 hours, $0.25. The LED costs $8.21 a year against the incandescent's $45.63, saving $37.41 per bulb — $149.65 for four bulbs and $1,496.50 over ten years. Long-burning bright bulbs are where switching pays fastest.
A small bulb, short hours, cheap power: 40W, 2 hours, $0.12. The LED costs $0.53 against $3.50, saving $2.98 per bulb per year. Still a saving, but a closet bulb switched for pennies a year is the last bulb to bother with, not the first.
One bulb vs ten bulbs, at the defaults. One bulb saves $9.49 a year; ten identical bulbs save $94.94 a year and $949.37 over ten years. A whole-house switch is a different purchase from a single-bulb switch — count your bulbs before you judge the prize.
| Output | Formula | What it means |
|---|---|---|
| LED equivalent | standard lumens mapping | 9W at the defaults — the LED wattage that gives the same ~800 lumens as a 60W incandescent. |
| Annual cost, each bulb | watts ÷ 1,000 × hours × 365 × rate | $1.68 LED vs $11.17 incandescent at the defaults, per bulb per year. |
| Saving per bulb | incandescent cost − LED cost | $9.49/yr at the defaults — what one switched bulb returns every year. |
| Annual saving, all bulbs | saving × bulb count | $37.97/yr at the defaults for 4 bulbs. |
| 10-year saving | annual saving × 10 | $379.75 at the defaults — the decade prize, before replacement-bulb savings. |
The arithmetic is exact for the inputs, but LED wattages are typical equivalents: two brands can both claim 800 lumens at 8W and 10W, so always buy by lumens. The model assumes the bulb burns the same hours every day of the year, holds the electricity rate flat for ten years, and ignores the purchase price of the bulbs themselves and the fact that incandescents burn out and must be replaced — both omissions favor the incandescent, so the true LED advantage is larger than shown. Dimmer use, enclosed fixtures, and color temperature do not change the energy math but can change which LED you should buy. Error policy: hours above 24, a negative rate, zero bulbs, or an unlisted wattage are reported as errors rather than modeled.
Bright Side Kit. "LED Bulb Wattage & Lumens Chart." https://brightoolbox.com/led-bulb-wattage-chart/ Accessed October 24, 2026.Data sourcesA 9W LED, giving about 800 lumens. Shop by lumens: the 60W number describes power used, while 800 lumens describes light produced, and the LED reaches the same light on a tenth of the power.
$11.17 at 3 hours a day and $0.17 per kWh. The same light from a 9W LED costs $1.68, so the switch saves $9.49 per bulb per year before replacement savings.
An 18W LED at about 1,600 lumens. At 3 hours a day and $0.17 per kWh it costs $3.35 a year against $18.62 for the incandescent, saving $15.26 per bulb.
Yes, by a watt or two at the same brightness. The chart's LED watts are typical equivalents. Always check the lumens printed on the box — that number, not the wattage, decides whether the room looks right.
Immediately, then steadily. Four 60W bulbs save $37.97 in the first year and $379.75 over ten years at the defaults, and the saving grows with hours, rate, and bulb count — a whole-house switch can pass $949.37 over ten years for ten bulbs.
Because the ten-year figure multiplies the unrounded saving, then rounds. The unrounded saving for four default bulbs is $37.9746 a year, so ten years is $379.75, not $379.70. Rounding only at display keeps the decade figure honest.
Bulb purchase prices, replacement frequency, dimmers, and rate changes. Incandescents burn out far more often than LEDs, so including replacements would widen the LED advantage, not shrink it.
The brightest bulbs that burn the longest. A 100W bulb at 5 hours a day saves $37.41 a year; a 40W closet bulb at 2 hours saves $2.98. Start with kitchens, living rooms, and porches.