Gas Bill Calculator Formula
Understand the math behind the gas bill calculator. Each variable explained with a worked example.
Formulas Used
Usage Charge
usage_charge = therms_per_month * rate_per_thermTotal Monthly Bill
total_bill = base_fee + therms_per_month * rate_per_thermAnnual Estimate
annual_estimate = (base_fee + therms_per_month * rate_per_therm) * 12Variables
| Variable | Description | Default |
|---|---|---|
therms_per_month | Monthly Therms Used(therms) | 50 |
rate_per_therm | Rate Per Therm(USD/therm) | 1.2 |
base_fee | Monthly Base/Delivery Fee(USD) | 12 |
How It Works
How Natural Gas Bills Work
Gas bills typically include a fixed delivery fee plus a per-therm usage charge.
Formula
Monthly Bill = Base Fee + (Therms Used x Rate Per Therm)
One therm = 100,000 BTU of natural gas energy.
Worked Example
50 therms per month at $1.20/therm with $12 base fee.
- 01Usage charge = 50 x $1.20 = $60.00
- 02Total bill = $12.00 + $60.00 = $72.00
- 03Annual estimate = $72.00 x 12 = $864.00
Frequently Asked Questions
What is a therm?
A therm is a unit of heat energy equal to 100,000 BTU. It is the standard billing unit for natural gas in the US.
How much gas does the average home use?
Average US household uses 50-80 therms per month in winter (heating) and 10-20 therms in summer (water heater and cooking only).
How can I lower my gas bill?
Lower your thermostat, improve insulation, seal air leaks, use a programmable thermostat, and maintain your furnace regularly.
Ready to run the numbers?
Open Gas Bill Calculator