Your approximate savings, pay-off, and lifespan are: Estimated energy savings per year   kilowatt hours Estimated savings per year $ Estimated ENERGY STAR® pay-off   months Estimated ENERGY STAR® lifespan   years Update any fields to evaluate another scenario. Existing incandescent light bulb size 25 40 60 75 100 150 watts Replacement ENERGY STAR® compact fluorescent bulb size 9 13 20 23 34 50 watts Number of light bulbs 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 bulbs Hours of use per day 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 hours Cost per incandescent light bulb 0 1 2 3 4 5 6 7 8 9 10 . 00 25 50 75 dollars Cost per ENERGY STAR® compact fluorescent bulb 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 . 00 25 50 75 dollars Electricity cost 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 . 0 1 2 3 4 5 6 7 8 9 cents per KWH Calculator provided courtesy of the sponsoring organizations of Northeast Energy Efficiency Partnerships, Inc. (NEEP).   Savings are for wattages shown.  Your actual savings will vary based on the wattages you purchase.  When comparing incandescent or halogen bulbs to ENERGY STAR qualified bulbs or fixtures, compare the light output, or lumens, and not Watts. Watts equal the energy used, not the amount of light.