Pilot lights use between 400 and 600 BTU per hour, which translates to roughly $0.50 to $2.00 per month depending on your gas rate and appliance type

A pilot light is a small, continuous flame that ignites your furnace, water heater, or stove burner when you need heat or cooking. Because it burns constantly—24 hours a day, 365 days a year—it does consume gas, but the amount is small enough that most households do not notice it on their bill. The actual cost depends on three things: your local gas price, the BTU rating of your specific pilot light, and how efficiently your appliance burns gas.

The typical pilot light consumes between 400 and 600 BTU (British Thermal Units) per hour. To put that in perspective, a full-size furnace burner uses 40,000 to 100,000 BTU per hour when running. A pilot light uses roughly one-tenth of one percent of what a main burner uses, which is why you can run one for a month and spend less than a dollar on the gas it consumes.

Key Takeaways

  • A pilot light burns 400 to 600 BTU per hour continuously, costing between $0.50 and $2.00 per month depending on your gas rate.
  • The actual monthly cost depends on your local natural gas price, which varies by region and utility company.
  • Pilot lights on water heaters and furnaces cost more to run than those on stoves because they burn larger flames.
  • Turning off a pilot light during warm months when you do not need heat can reduce your gas bill, but relighting it requires care or professional help.
  • Modern appliances with electronic ignition instead of pilot lights eliminate this cost entirely, though they require electricity instead.

How pilot light gas use breaks down by appliance type

Different appliances have different pilot light sizes, so their gas consumption varies. A water heater pilot light typically burns 400 to 500 BTU per hour and runs year-round. A furnace pilot light is similar—usually 350 to 500 BTU per hour—but only needs to run during heating season in most climates. A stove or range pilot light is smaller, often 75 to 150 BTU per hour, because it only needs to ignite a burner when you turn a knob.

If you have a water heater with a pilot light running 24/7 at 450 BTU per hour, and your gas costs $1.20 per therm (a therm is 100,000 BTU), that pilot light costs roughly $1.30 per month. A furnace pilot light running only during a six-month heating season at the same rate costs about $0.40 for those months. Stove pilots cost even less because they burn so small.

What your local gas rate means for pilot light cost

Gas prices vary significantly by region and utility company. Some areas pay $0.80 per therm; others pay $1.50 or higher. This difference alone can double or halve what your pilot light costs to run. To find your rate, check your most recent gas bill—it will show your price per therm or per cubic foot.

Once you know your rate, you can calculate roughly what a pilot light costs. A 450 BTU pilot light running 24 hours uses 10,800 BTU per day, or 324,000 BTU per month. Divide that by 100,000 to get therms (3.24 therms), then multiply by your rate. At $1.20 per therm, that is $3.89 per month. At $0.80 per therm, it is $2.59. The math is straightforward, but the rate is the variable that matters most.

Seasonal shutoff: when it makes sense to turn off a pilot light

If you have a furnace with a pilot light, you can turn it off during months when you do not need heat. In a warm climate or during summer, this saves money with no downside—you straightforward relight it when heating season returns. Many people do this and see a small but real reduction in their gas bill from May through September.

Turning off a pilot light is straightforward: locate the control knob on your furnace or water heater, turn it to the "off" position, and wait a few minutes for the flame to die. Relighting requires holding the knob in the "pilot" position while you light it with a long lighter or match, then holding it there for 30 to 60 seconds while the thermocouple (a heat-sensing device) warms up. If you are uncomfortable doing this, a technician can do it for $50 to $100. For a water heater, seasonal shutoff is less common because you usually want hot water year-round, but it is an option if you are away for months at a time.

Electronic ignition as an alternative to pilot lights

Modern furnaces, water heaters, and stoves increasingly use electronic ignition instead of pilot lights. These systems use a spark or hot surface to ignite the burner only when needed, then shut off when ready after. They eliminate the continuous gas burn entirely, which saves money and reduces energy waste.

The trade-off is that electronic ignition requires electricity. If your power goes out, you cannot light your furnace or water heater until power returns—whereas a pilot light will keep burning. For most households, this is not a practical concern because furnaces and water heaters have backup power or the outage is brief. If you live in an area with frequent or extended outages, a pilot light is more reliable.

If you are replacing an appliance, electronic ignition is now the standard on most new models. The gas savings over the life of the appliance are modest but real, and the environmental benefit of not burning gas continuously is meaningful.

Why pilot lights exist and when they might fail

Pilot lights exist because they provide a reliable, always-ready source of ignition. Before electronic ignition became affordable and reliable, they were the only practical way to light a burner on demand. They still serve this purpose well, which is why older appliances and some newer budget models still use them.

A pilot light can fail for several reasons: the thermocouple wears out and no longer signals the gas valve to stay open, the pilot orifice clogs with dust or debris, or the gas supply is interrupted. If your pilot light goes out, you will notice it when ready—your furnace or water heater will not heat. Relighting it is usually straightforward, but if it goes out repeatedly, the thermocouple likely needs replacement, a job that costs $150 to $300 and requires a technician.

Comparing the total cost of running a pilot light over time

Over a year, a water heater pilot light costs between $6 and $24, depending on your gas rate. A furnace pilot light costs between $2 and $8 during the heating season. These are small numbers, which is why most people do not think about pilot lights when looking at their gas bill. However, if you have multiple appliances with pilot lights—a furnace, water heater, and stove—the combined cost can reach $30 to $50 per year.

If you are trying to lower your gas bill, pilot lights are not the place to start. Insulating your water heater, lowering your thermostat by a few degrees, and fixing air leaks will save far more. But if you are replacing an old appliance anyway, choosing one with electronic ignition will eliminate this cost and reduce your overall energy use.

Frequently Asked Questions

Does a pilot light use more gas than I think?

No. A pilot light uses roughly one-tenth of one percent of what a main burner uses. At typical gas rates, it costs less than $2 per month on a water heater and even less on a furnace or stove. Most people do not notice it on their bill because the amount is so small.

Can I save money by turning off my water heater pilot light in summer?

Yes, but the savings are modest—roughly $1 to $2 per month. If you are away for an extended period, it is worth doing. If you are home and want hot water, the cost of running the pilot is less than the inconvenience of relighting it when you return.

What does a thermocouple do, and why does it matter?

A thermocouple is a heat-sensing device that tells your gas valve the pilot light is burning and it is safe to keep the gas flowing. If it fails, the pilot light will not stay lit. Replacement costs $150 to $300 and requires a technician.

Is it dangerous to have a pilot light burning all the time?

No. Pilot lights are designed to burn continuously and safely. They produce a small, stable flame and are vented properly so combustion byproducts exit your home. The only risk is if the appliance is damaged or the vent is blocked, which would be dangerous regardless of the pilot light.

Should I replace my appliance with a pilot light with one that has electronic ignition?

If your current appliance is working well, there is no urgent reason to replace it. The gas savings from electronic ignition are real but small—roughly $10 to $30 per year. When you do replace the appliance, electronic ignition is now standard on most new models, so you will get it automatically.