Tool · Investor Sam Green

Home Energy Cost Estimator

June 30, 2026 • By the Investor Sam Editorial Team • Reviewed by Berly Sam Varghese, Editor
Your home energy cost is really two bills in one: electricity measured in kilowatt-hours and, for many homes, natural gas measured in therms. This calculator combines both at your local rates to give a single monthly and annual figure, so you can budget accurately, spot when a bill is out of line, and measure the impact of efficiency upgrades against a clear baseline.

Example: Monthly electricity use: 900 kWh · Electricity rate: 0.17 $/kWh · Monthly natural gas use: 50 therms · Natural gas rate: 1.4 $/therm

Total monthly energy cost$223
Total annual energy cost$2,676
Monthly electricity portion$153

Worked example

A home using 900 kWh of electricity at $0.17 per kWh spends $153 on power, and 50 therms of gas at $1.40 per therm adds $70, for a combined $223 a month. Over a year that is about $2,676. Splitting the bill this way shows electricity is the larger share here, so efficiency efforts — LEDs, a smart thermostat, appliance upgrades — should target the electric side first.

Frequently asked questions

Where do I find my usage and rates?

Your electric and gas bills list monthly usage in kilowatt-hours and therms, plus the rate you pay per unit. Use a recent bill, or average a few months to smooth out seasonal swings. If you have no gas service, set the gas figures to zero and the tool computes electricity only.

Why combine electricity and gas?

Many efficiency decisions trade one fuel for another — a heat pump shifts heating from gas to electricity, for example. Seeing your total energy cost in one number lets you judge those trade-offs fairly and track whether your whole-home spending is going down, not just one bill.

How do I use this to check for a problem?

Establish your normal monthly figure, then watch for a bill that jumps well above it without a weather reason. A sudden spike can signal a failing appliance, a heating or cooling system running too hard, or a rate change. The baseline here is what makes an anomaly obvious.

Does this include fixed charges and taxes?

This estimate covers the usage-based portion of your bills. Most utilities also add fixed monthly service charges, delivery fees, and taxes. Add those flat amounts to the result for your true all-in bill, but the usage portion is where efficiency upgrades move the needle.

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Sources

Berly Sam Varghese · Editor, Investor Sam

Berly Sam Varghese is an engineer who treats money the way he treats any hard problem — something to be engineered, not gambled on. He funded years of education and built real financial stability the patient way, by living below his means and investing rather than borrowing. He writes for the person trying to make a greener choice that also makes financial sense. He reviews and approves every article on Investor Sam and checks the figures against primary sources before anything is published. More about our standards.