Smart Thermostat Savings Calculator
Enter what heating and cooling cost you, and see about what a smart thermostat could save and when it pays for itself.
Sample numbers only, to show how it works. Replace them with yours.
Enter what heating or cooling costs you in a year (from your bills).
This is an estimate, not a professional calculation. See the disclaimer and the methodology.
How it is calculated
Saving = yearly heating cost × heating saving percent + yearly cooling cost × cooling saving percent. Payback in years = price of the thermostat ÷ yearly saving.
The percentages start at ENERGY STAR certification criteria for connected thermostats. ENERGY STAR requires that field data show an average reduction in annual run time of at least 8 percent for heating and 10 percent for cooling (it sets these as the lower 95 percent confidence limit of a weighted national average). These are thresholds for a certified product and an average across many homes. They are not a promise for any one home.
Run time is not cost. The calculator treats a saving in run time as the same share of cost, which is an approximation. If your system uses a fuel or a stage that does not fall in step with run time, the cost saving can be different.
Enter the costs from your own bills: the heating part is the winter use above your mild-month use, and the cooling part is the summer use above it. Leave one empty if you have no heating or no cooling cost. You can change the percentages if you expect more or less.
The result does not count the cost of installation, a subscription or any rebate. Some thermostats need a wire the system may not have.
Worked examples
Heating and cooling costs of $900 and $400
With ENERGY STAR's 8 percent for heating and 10 percent for cooling (and costs assumed for this example), the saving is $72 on heating and $40 on cooling, $112 a year. A $250 thermostat (assumed) would pay back in about 2.2 years.
Only heating
If you only heat, with $1,500 of heating cost (assumed), 8 percent is $120 a year.
If you save more than the minimum
Double the percentages, to 16 and 20, and the same costs give $224 a year. Manufacturers publish their own figures, which can be higher; the calculator lets you test them.
Frequently asked questions
Does a smart thermostat save money?
ENERGY STAR requires certified connected thermostats to show an average reduction in run time of at least 8 percent for heating and 10 percent for cooling. How much that saves in dollars depends on your bills and your habits.
Where do the percentages come from?
From the ENERGY STAR key product criteria for smart thermostats, Table 2 on connected thermostat energy savings. They are certification thresholds, so a certified model may do better, and any one home may differ.
How much of my bill goes to heating and cooling?
ENERGY STAR says that for the average American household almost half of the annual energy bill goes to heating and cooling, more than $900 a year. Your own bills are the best source: compare a winter and a summer month with a mild month.
Is a smart thermostat better than a programmable one?
We have no verified comparison, so the calculator does not give one. It estimates the saving of a smart thermostat from the percentages you choose.
Will it work with my heating and cooling system?
Compatibility depends on your system and wiring, and some thermostats need a common wire. Check the maker's compatibility tool before you buy.
Related calculators
Sources and last update
- ENERGY STAR, Smart Thermostats key product criteria (Table 2, connected thermostat energy savings)
- ENERGY STAR, Smart Thermostats
Last updated: November 3, 2026. See methodology and sources.