Smart & Programmable Thermostat Savings Calculator
Enter your annual heating and cooling bill and your planned setback schedule. We use the U.S. Department of Energy's validated 1%/degree/8-hour formula to estimate realistic savings.
Last verified: April 29, 2026
Heating savings
$120
per year
Cooling savings
$20
per year
Total annual savings
$140
per year
- Heating % saved
- 10%
- Cooling % saved
- 5%
- New annual HVAC total
- $1,460
- Payback period
- 1.1 yrs
Based on the U.S. DOE 1% per degree per 8-hour setback formula. Actual savings depend on climate, home insulation, and HVAC system type.
How this is calculated
The U.S. Department of Energy established that each 1°F setback sustained for 8 hours reduces heating/cooling energy by approximately 1%.
Savings % = (Degrees × Hours ÷ 8) × 1%
Annual saving = Bill × Savings %
Example (8°F heating setback for 8 hrs/day on a $1,200 heating bill):
Heating savings % = (8 × 8 ÷ 8) × 1% = 8%
Heating savings = $1,200 × 8% = $96/yr
Example (4°F cooling setback for 9 hrs/day on a $400 cooling bill):
Cooling savings % = (4 × 9 ÷ 8) × 1% = 4.5%
Cooling savings = $400 × 4.5% = $18/yrAssumptions
- Based on U.S. DOE guidance: 1% savings per 1°F setback per 8 hours per day
- Assumes HVAC efficiency stays constant during recovery from setback
- Formula may overestimate savings for heat pumps — use smaller setbacks (2–4°F)
- Does not account for solar gain, home thermal mass, or local climate variation
- Payback period = thermostat cost ÷ total annual savings
Frequently asked questions
How much does a smart thermostat actually save? ▾
The U.S. Department of Energy estimates savings of about 1% per degree Fahrenheit for each 8-hour setback period per day. Ecobee's own data from 4 million homes found average savings of 23% on heating and cooling. Nest reports 10–12% on heating and 15% on cooling. Results vary significantly by climate, home size, and existing habits.
What is a "setback" temperature? ▾
A setback is when you lower your heating (or raise your cooling) target temperature during periods you don't need full comfort — typically while sleeping or away. For example, setting heat from 70°F down to 62°F for 8 hours overnight is an 8-degree heating setback.
Does a bigger setback always save more money? ▾
Generally yes, up to a point. Very large setbacks (more than 10°F) may cause your system to work harder to recover — potentially offsetting some savings. In well-insulated modern homes, recovery is fast. In leaky older homes, large setbacks may be less efficient.
Does setback work the same for heat pumps? ▾
Heat pumps are less suited to large temperature setbacks because they recover slowly. Large setbacks can trigger electric resistance backup heat ("emergency heat"), which is far less efficient. For heat pumps, smaller setbacks of 2–4°F are typically recommended.
How long does a smart thermostat take to pay for itself? ▾
Most smart thermostats cost $100–$250. At $50–$150 in annual savings (depending on your bill and habits), payback is typically 1–3 years. After that, savings continue for the thermostat's 10+ year lifespan.
Sources
- U.S. Department of Energy — Thermostats — 1% per degree per 8-hour setback rule and savings guidance (last checked 2026-04-29)
- ENERGY STAR — Programmable Thermostats — Smart thermostat efficiency recommendations (last checked 2026-04-29)