How to Use the Heating Cost Calculator
How warm you keep your home has a big effect on your heating bill. This calculator takes your target indoor temperature, average outdoor temperature, heated floor area, daily heating hours, and natural gas price, then estimates your daily gas usage (in therms) and monthly heating cost. It uses an approximate heat loss coefficient (about 0.184 BTU/ft²·h·°F), a standard gas heating value (100,000 BTU/therm), and an 85% furnace efficiency.
The bigger the gap between your target indoor temperature and the outdoor temperature, the more heat your furnace has to produce, and the higher your bill climbs. Lowering your thermostat by even a degree or two can noticeably cut gas usage, and reducing daily heating hours or improving insulation can lower costs further.
Keep in mind this is an estimate based on a standard heat loss coefficient. Your actual bill depends on your home's insulation, window quality, your furnace's real-world efficiency, and day-to-day weather, so treat the result as a planning guide and check your actual utility bill for the exact amount.
Frequently Asked Questions
We estimate the heat load from your area and indoor-outdoor temperature difference, then convert it to therms of natural gas using a standard heating value (100,000 BTU/therm) and an 85% furnace efficiency, and multiply by your gas price.
Yes. Insulation quality, window performance, your furnace's real efficiency, and outdoor temperature swings can all change actual usage. This calculator gives a rough estimate, not an exact bill.