How much does it cost to run an incandescent bulb?
Incandescent bulbs are the oldest and simplest form of electric lighting, producing light by heating a tungsten filament until it glows. Despite their warm, pleasant light quality, they waste approximately 90% of their energy as heat rather than visible light, making them among the least efficient lighting options available today.
Incandescent Bulb running cost calculator
- Per day
- $0.06
- Per month
- $1.86
- Per year
- $22.34
- CO₂ / year
- 52.6 kg
Based on 131.4 kWh per year. Adjust the price per kWh to match your latest electricity bill for an exact figure.
At 60 watts used 6 hours a day, an incandescent bulb costs about $0.06 per day, $1.86 per month and $22.34 per year on an average rate of 17¢ per kWh — roughly 131.4 kWh and 52.6 kg of CO₂ over a year. Enter your own electricity rate and usage in the calculator above for a figure matched to your bill.
The fundamental physics of incandescent technology drives its high energy consumption. When electricity passes through the tungsten filament, resistance causes it to heat up to around 2,700 Kelvin—hot enough to emit visible light across the spectrum, but also releasing enormous amounts of infrared radiation that never reaches your eyes. This is why incandescent bulbs get so hot to the touch and why you feel warmth radiating from them even from a distance. A 60-watt incandescent bulb typically delivers only 5 to 8 watts worth of actual visible light, with the rest dissipating as heat.
The lifespan of an incandescent bulb—typically 1,000 hours—directly reflects this inefficient burning process. The tungsten filament gradually evaporates during use, becoming thinner and weaker until it finally breaks and the bulb fails. This is why incandescent bulbs have always been considered disposable items, and why the cost of frequent replacement adds up over time. In household applications where a bulb burns six hours daily, a typical incandescent bulb lasts less than a year, requiring regular purchases and the hassle of changing fixtures.
When choosing an incandescent bulb, wattage is the primary way to control brightness, but this creates a false economy. A 60-watt incandescent and a 75-watt incandescent may not seem dramatically different in the store, but that extra 15 watts represents a 25% increase in energy consumption. Selecting the lowest wattage that provides adequate light—rather than automatically choosing what feels brightest—is one practical way to reduce the running costs shown above. Additionally, using bulbs in fixtures with dimmer switches or three-way sockets allows you to lower brightness when full illumination isn't necessary.
The widespread availability of incandescent bulbs in hardware stores and the low upfront purchase price have historically made them the default choice, but this ignores the true cost of ownership. The combination of short lifespan, frequent replacement, and continuous energy draw throughout their brief operational life makes incandescent lighting expensive relative to modern alternatives. The figures above capture this reality by showing not just the per-bulb cost, but the cumulative impact of lighting a space reliably over months or years. Understanding this longer-term perspective helps explain why so many households and businesses have shifted away from incandescent technology.
Frequently asked questions
- Why do incandescent bulbs get so hot if most of the energy goes to light?
- Incandescent bulbs actually produce light as a byproduct of heat. The filament glows because it's extremely hot—around 2,700 Kelvin. The majority of the energy radiated by this hot filament is infrared radiation (heat) rather than visible light. So when you feel warmth from an incandescent bulb, you're experiencing the primary output of the device, not wasted energy that's incidental to the lighting process.
- Does the brightness (lumens) of an incandescent bulb affect how much it costs to run?
- Brightness is controlled by increasing the wattage, so a 75-watt incandescent bulb will use approximately 25% more energy than a 60-watt bulb and will cost proportionally more to run. However, incandescent bulbs have no separate efficiency rating—the relationship between wattage and brightness is largely fixed by the technology itself. This is different from LED bulbs, where two bulbs of the same brightness may use very different amounts of power depending on their design.
- Can you extend the life of an incandescent bulb to reduce how often you replace it?
- Some strategies can marginally extend incandescent bulb life, such as using them in fixtures without vibration or physical stress, avoiding frequent on-off switching (which stresses the filament), and operating them at slightly reduced voltage through dimmers. However, these measures only add a few months at best. The fundamental evaporation of the tungsten filament is unavoidable, so expecting a typical bulb to last significantly longer than 1,000 hours is unrealistic.
- Are there situations where incandescent bulbs are still the better choice?
- Incandescent bulbs excel at producing warm, pleasing light and work well in fixtures with dimmer switches if modern dimmable alternatives aren't available. They also have no warm-up time like some older CFLs. However, for most everyday household lighting, the energy cost and frequent replacement make them economically unattractive compared to LEDs, which now offer warm color temperatures and full dimming capability.
- How does the wattage listed on an incandescent bulb relate to its actual brightness?
- Incandescent bulbs produce roughly 15-17 lumens per watt, meaning a 60-watt bulb produces around 900-1,000 lumens. This relationship is fairly consistent across incandescent models because the technology hasn't fundamentally changed. LED bulbs, by contrast, vary much more widely in efficiency—some produce 80+ lumens per watt—which is why you can't simply compare wattage between incandescent and LED to predict brightness.
- What happens to the cost of running an incandescent bulb if you use it more than the typical 6 hours per day?
- The cost scales linearly with usage time. A bulb that runs 12 hours per day instead of 6 hours per day will cost roughly twice as much to operate, and will also fail in roughly half the calendar time (though still after approximately 1,000 operating hours). This makes incandescent lighting particularly expensive in high-use applications like kitchens, hallways, or outdoor fixtures that are on for extended periods.