Thermostat savings calculator
Enter your yearly heating and cooling cost, how many degrees you turn the thermostat back and for how many hours a day. The estimate uses a rule of thumb and is only a ballpark.
Runs in your browser: nothing you enter is sent anywhere.
How to use it
- Enter what you spend a year on heating and cooling.
- Choose °C or °F and enter the setback: how far the thermostat is moved from your normal setting.
- Enter the hours per day you keep the setback, for example while asleep or away, and the days a year you do it.
- Read the estimated percentage, yearly savings and the cost afterwards.
How it is calculated
This is a rough rule of thumb, not a physical model:
- Savings percent = 1 × setback in °F × (hours ÷ 8) × (days ÷ 365), at most 10.
- A setback in °C is multiplied by 1.8 to get °F.
- Savings = yearly cost × percent ÷ 100. Cost after setback = cost − savings.
Worked example
Yearly cost 1,200, a 7 °F setback for 8 hours a day all year: 7 × 1 × 1 = 7 percent, or 84 saved. A 15 °F setback would give 15 percent by the formula but is capped at 10 percent, which is 120.
Tips
Setbacks are easiest to apply while you sleep or are out. A programmable or smart thermostat can do it automatically.
Frequently asked questions
Where does the estimate come from?
The US Department of Energy is commonly cited as saying you can save up to about 10 percent a year on heating and cooling by turning the thermostat back 7 to 10 °F (about 4 to 6 °C) for 8 hours a day. This calculator turns that into a rough rule of thumb of about 1 percent per °F of setback for 8 hours, scaled by hours and days, and capped at 10 percent.
Is the result accurate for my home?
No, it is a ballpark. Real savings depend on climate, insulation, the heating or cooling system and how you live. A heat pump or a very leaky house can behave differently.
Does it work for both heating and cooling?
The same rule of thumb is cited for both: lower the thermostat in winter, raise it in summer. Enter the combined yearly cost, or only the part where you use the setback.
Why is the saving capped at 10 percent?
The cited figure is an upper estimate of about 10 percent, so the calculator does not go beyond it even for very large setbacks.