Thermostat Setback Savings Calculator
See how much you save by turning your thermostat down in winter or up in summer. Anchored to your real bill using the Department of Energy’s setback rule of thumb.
See how much you'll save by turning the thermostat back. Enter your current heating or cooling bill and the setback you have in mind — you'll get the savings in dollars, plus your new, lower bill.
Heating or cooling?
Whether you're estimating winter heating savings (turning the thermostat down) or summer cooling savings (turning it up).
Your current monthly bill
What you pay per month to heat (or cool) during the season — this is the number the savings is calculated from. Use the heating part of a winter gas/electric bill, or the cooling part of a summer bill.
Months per year
How many months a year you run heating (or cooling). A typical heating season is 4–6 months; cooling 3–5, depending on your climate.
Setback amount
How many degrees you turn the thermostat back — cooler in winter, warmer in summer — versus your normal setting.
Hours per day at setback
How many hours a day the thermostat stays at the setback temperature — for example, 8 hours while you sleep, or more if you’re also out during the day. Use 24 for a permanent change.
You'd Save Each Year
$60/yr
by turning the thermostat down 8°F for 8 hrs/day
A solid, easy win
This is a meaningful chunk off your bill for a change you barely notice. Going a few degrees deeper or extending the hours raises it further, and a programmable thermostat makes the setback automatic so you never forget it.
| Turn it down 2°F | $15/yr |
| Turn it down 4°F | $30/yr |
| Turn it down 6°F | $45/yr |
| Turn it down 8°F— your pick | $60/yr |
| Turn it down 10°F | $75/yr |
Same bill and hours — only the temperature change differs. A small nudge saves little; a bigger change saves proportionally more.
This is an estimate based on the U.S. Department of Energy guideline that you save roughly 1% on heating or cooling for each degree of setback over an 8-hour period. Real savings vary widely with your climate, insulation, and equipment — smaller in mild weather, larger in extremes. One important exception: homes with a heat pump can see little benefit, or even higher costs, from deep setbacks, because the system runs inefficient backup heat to catch back up. For heat pumps, keep setbacks shallow or use a thermostat designed for them. Savings here are capped at 40% to stay realistic.
💡About this calculator▼
"Does turning the thermostat down actually save money — and how much?" It does, and this calculator puts a real dollar figure on it, tailored to your own bill rather than a generic national average.
Tell it whether you're heating or cooling, enter your typical monthly cost for that season, and describe the setback you have in mind: how many degrees you'll turn the thermostat back and for how many hours a day. You'll get the estimated savings per month and per year, plus your new seasonal cost.
The estimate is built on the U.S. Department of Energy's well-known guideline — you save roughly 1% on heating or cooling for each degree you set back over an 8-hour period — applied to the actual cost you enter. That keeps it grounded and honest: instead of guessing at your home's insulation and equipment, it scales your real bill by a defensible rule of thumb, and it's upfront about where that rule doesn't hold (notably heat pumps and mild climates).
The calculator turns a temperature change into a percentage saving, then applies that percentage to the bill you enter.
It starts from the Department of Energy's rule of thumb: turning your thermostat back about 1 degree for an 8-hour stretch each day saves roughly 1% on your heating or cooling. So the savings scale with two things you control — how many degrees you set back, and how many hours a day you hold that setback. A deeper setback or a longer one saves more; an 8-degree setback for 8 hours lands around 8%, close to the DOE's "up to 10% a year" figure for a 7–10 degree setback.
It multiplies your degrees × (hours ÷ 8) × 1% to get a savings rate, capped at a realistic 40% so extreme inputs don't produce fantasy numbers. Then it applies that rate to your seasonal cost — your monthly bill times the number of months you run the system — to get annual savings, and to a single month to show the monthly figure.
This bill-anchored approach is deliberately simple. Modeling true savings would require your climate, insulation, duct losses, and equipment efficiency — and would still be an estimate. Scaling your real bill by the DOE guideline is transparent, hard to get badly wrong for a typical furnace or AC, and easy to sanity-check. The exact formula, a worked example, and the important exceptions are below.
📐How it's calculated▼
The estimate converts your setback into a savings rate, then applies it to your bill.
Step 1 — Savings rate: Savings rate = Degrees × (Hours per day ÷ 8) × 1% (capped at 40%)
Step 2 — Seasonal cost: Seasonal cost = Monthly cost × Months per year
Step 3 — Savings: Annual savings = Seasonal cost × Savings rate Monthly savings = Monthly cost × Savings rate New seasonal cost = Seasonal cost − Annual savings
Example: Heating, $150/month over a 5-month season, an 8°F setback for 8 hours a day
→ Savings rate: 8 × (8 ÷ 8) × 1% = 8%
→ Seasonal cost: $150 × 5 = $750
→ Annual savings: $750 × 8% = $60
→ New seasonal cost: $750 − $60 = $690
So a setback you'd barely notice — 8 degrees overnight — trims about $60 off the heating season. Double the hours (a setback while you're also out at work) and the rate roughly doubles too.
📎Source: U.S. Department of Energy — Energy Saver: Thermostats
🔍Finding your inputs▼
Heating or cooling: Choose heating to estimate winter savings from turning the thermostat down, or cooling for summer savings from turning it up. The math is the same; only the direction and wording change.
Your current monthly bill: Your typical heating or cooling cost for one month during the season. The cleanest source is a bill from the heart of the season — a January gas bill for heating, a July electric bill for cooling. If your bill lumps everything together, estimate the heating or cooling portion by subtracting a mild "shoulder-month" bill (like April or October) from the peak-season bill; the difference is roughly what climate control is costing you.
Months per year: How many months you actually run the system. Heating seasons are commonly 4–6 months; cooling 3–5, longer in hot climates. This converts your monthly figure into a seasonal and annual total, so be realistic about the length of your season.
Setback amount: How many degrees you'll move the thermostat from its normal setting — down for heating, up for cooling. A common, comfortable overnight setback is 7–10°F. Bigger setbacks save more, but only set back as far as stays comfortable and safe (don't let pipes get cold enough to freeze).
Hours per day at setback: How long each day the thermostat sits at the setback temperature. Eight hours covers a typical night's sleep. If you also set back while everyone's out during the day, you might hold it for 14–16 hours. Enter 24 if you're simply keeping the house at a permanently lower (or higher) temperature around the clock.
⚠️Special situations▼
I have a heat pump
This is the big exception, so treat the estimate with caution. Many heat pumps lose efficiency recovering from a deep setback, because catching up several degrees triggers the electric-resistance backup heat — the most expensive way these systems can run. The result is that a large setback can save little or even cost more. If you have a heat pump, keep setbacks small (around 2–4°F), or use a thermostat specifically designed for heat pumps that ramps the temperature back gradually. A steady, modest setting often beats aggressive setbacks here.
I live in a mild climate
The percentage savings from a setback are largest when the gap between indoor and outdoor temperature is large — bitter cold or intense heat. In a mild climate, or during mild shoulder months, your system runs less to begin with, so the same setback returns fewer dollars. The estimate here can run optimistic in those conditions. The flip side: in a harsh climate or a brutal cold snap, real savings can exceed the rule-of-thumb figure.
I want to know my exact heating or cooling cost
Utility bills usually bundle heating, cooling, and base usage together. To isolate the climate-control portion, compare a peak-season bill (deep winter or peak summer) against a mild shoulder-month bill (spring or fall) when you barely run the system: the difference is roughly your heating or cooling cost for that month. Use that figure as your monthly cost here for a more accurate result than using the whole bill.
Is a smart thermostat worth buying for this?
It depends on your savings and the price. If this calculator shows you saving, say, $100–$200 a year and you're not already setting back manually, a programmable or smart thermostat (often $50–$250) can pay for itself in a season or two — and it captures savings you'd otherwise forget. If your estimated savings are small, or you already set back by hand reliably, the payback is longer and it's more about convenience. Check for utility rebates, which frequently knock a chunk off smart-thermostat prices.
Won't reheating the house use up all the savings?
No — this is a common myth. Your home loses heat fastest when the inside-to-outside temperature gap is largest, so letting the house cool while you're asleep or away reduces total heat loss over those hours. The energy to reheat is less than what you saved by letting it coast cooler, which is exactly why setbacks work for standard furnaces and air conditioners. (The one real exception is heat pumps with electric backup, covered above.)
❓Common questions▼
How much does turning down the thermostat actually save?
As a rule of thumb, the U.S. Department of Energy estimates you save about 1% on heating for each degree you set the thermostat back over an 8-hour period — roughly 10% a year for a 7–10°F setback while you sleep or are away. On a $150/month, 5-month heating season, an 8-degree overnight setback works out to around $60 a year. Enter your own bill and setback above for a figure tailored to you. The same idea applies to cooling in summer.
What temperature should I set my thermostat to save money?
The DOE commonly suggests around 68°F in winter while you're home and awake, set lower while asleep or away; and around 78°F in summer when home, higher when out. But the exact comfortable number matters less than the habit of setting back: every degree and every hour of setback adds savings. Use this calculator to see what a given setback is worth to you, then pick the deepest setback that still feels comfortable.
Does setting back the thermostat work with a heat pump?
Less reliably, and that's the key caveat. Recovering from a deep setback can trigger a heat pump's electric-resistance backup heat, which is expensive enough to wipe out the savings or even raise your bill. With a heat pump, use small setbacks (a few degrees) or a thermostat designed to manage heat-pump recovery gradually. For standard gas furnaces and air conditioners, larger setbacks save reliably.
Does it cost more to reheat a house than to keep it warm?
No, that's a myth for conventional systems. A house loses heat fastest when it's warmest relative to outside, so letting it cool during a setback lowers total heat loss, and the energy to bring it back up is less than what you saved. That's why setbacks net out positive for furnaces and ACs. The exception is a heat pump that leans on electric backup heat to recover, which can change the math.
How accurate is this estimate?
It's a grounded rule-of-thumb estimate, not a precise measurement. It scales your actual bill by the DOE's per-degree guideline, which is reasonable for typical furnaces and air conditioners but varies with your climate, insulation, and equipment — smaller savings in mild weather, larger in extremes, and unreliable for heat pumps with electric backup. Use it to gauge whether a setback (or a programmable thermostat) is worth it, and treat the dollar figure as a ballpark rather than a guarantee.