Thermostat Savings Calculator
Yearly dollars saved by setting back degrees and hours.
What it does
Thermostat setback saves roughly one percent per degree lowered across eight daily hours: cooler walls leak less heat around the clock. Seven degrees over sleep and work hours cuts about seven percent yearly.
The tool above takes the monthly bill with setback degrees and daily hours. It returns yearly with monthly savings and the percent cut beside them.
The default $150 bill with 7 F back 8 hours daily saves $126.00 a year ($10.50 a month, 7%). A $200 bill with 5 F back saves $120.00 at 5%.
The rule follows Department of Energy thermostat guidance with Energy Star heating references behind it. Both cap expectations: setbacks help heating most, cooling less, heat pumps need smart recovery.
How to use
- Enter the average monthly heating bill.
- Enter degrees lowered in Fahrenheit.
- Enter daily setback hours.
- Read yearly first for the prize.
- Program the thermostat so it actually happens.
Formula
- 1%
- Savings per degree per 8 hour habit.
- hours/8
- Scaling for shorter or longer setbacks.
- x12
- Yearly total from monthly bill.
Heating season math; cooling setbacks save less per degree. Heat pump users need adaptive recovery or savings evaporate into backup heat.
Worked example
Example: $150, 7 F, 8 h
Defaults: bill 150, degrees 7, hours 8.
- Percent: 7 x (8/8) = 7%.
- Yearly: 150 x 12 x 0.07 = $126.00.
- Monthly: 126 / 12 = $10.50.
- Check: 10% would need 10 F back.
- Tool shows $126.00 /yr, 7%, $10.50 /mo.
Reference table
| Setback | Percent | Yearly |
|---|---|---|
| 3 F | 3% | $54.00 |
| 5 F | 5% | $90.00 |
| 7 F | 7% | $126.00 |
| 10 F | 10% | $180.00 |
Limits
- Heating estimates; cooling differs.
- Rule of thumb, not metered audit.
- Heat pumps need recovery logic.
- Drafty homes save more per degree.
Common mistakes
- Setting back heat pumps like furnaces.
- Counting cooling savings at heating rates.
- Forgetting to program consistently.
- Heating empty rooms alongside.
- Ignoring filter and maintenance losses.
Try it yourself
Quick checks. Answers sit tucked under each question.
$200, 5 F, 8 h?
5%: 200 x 12 x 0.05 = $120.00 a year.
4 h instead of 8?
Halves it: 7 F gives 3.5%.
Monthly of $126 yearly?
126 / 12 = $10.50 a month.
Questions
How much does 7 F save?
About 7% yearly at 8 h daily: $126 on $150 bills.
Does it work for cooling?
Yes but less per degree; raising temperature saves similarly.
Heat pumps too?
With smart recovery only; crude setbacks trigger backup heat.
Manual or programmable?
Programmable or smart: consistency makes the savings.
Why 8 hours?
Sleep plus work absence: the standard baseline window.
Bigger setbacks better?
To comfort limits; pipes and humidity set floors.