Natural Gas Bill Calculator

A therm is the standard unit for measuring the energy content of natural gas in the US (1 therm = 100,000 BTU). Utilities use therms because they reflect actual heat energy, not just volume (CCF). This calculator works with therms for the most accurate bill estimate.

Simply use the built-in meter tool above! Enter current and previous readings — it instantly multiplies CCF by 1.038 (the exact conversion factor used by most US utilities). Or use the quick “Use This Usage” button.

Look for “Gas Supply Charge” + “Delivery Charge” (sometimes called “Distribution”). Add them together and divide by your usage in therms. Most bills show this clearly near the bottom. Typical US residential rate: $1.40 – $2.10/therm.

The service (or base) charge covers the fixed cost of maintaining the gas line to your home. It appears every month regardless of usage — that’s why it’s listed separately in the calculator.

Yes! Just enter your local tax & surcharge percentage (usually 5–9%). The calculator automatically adds it to the subtotal so you see your true estimated bill.

Yes — most utilities have higher delivery rates in winter (Oct–Mar) due to demand. Use the “Cold Month” preset button and check your latest bill for seasonal adjustments.

Absolutely! It works for any residential or small commercial account. Just make sure you use your actual rates and usage from your bill (large commercial accounts may have different tiered rates).

95%+ accurate when you input your real rates from your latest bill. It won’t match 100% if your utility uses complex tiered pricing or weather adjustments, but it’s the closest free tool available.

For most accurate results, calculate your average rate: total gas cost ÷ total therms. Enter that average in the “Rate per Therm” box. You can also run the calculator multiple times for different usage blocks.

100% free, no ads, no sign-up, and completely private — everything runs in your browser. We never see your numbers. Bookmark it and use it every month!