Best Thermostat Settings for Winter, Summer, Sleep and Away

1. Recommended thermostat settings at a glance

There is no single “correct” temperature: comfort depends on clothing, humidity, age and health. But there are good starting points, and almost all of the savings come from one habit: a lower setting while nobody needs the heat, and a higher one while nobody needs the cooling.

2. Best thermostat setting in winter

The Department of Energy’s suggestion is 68°F while you are awake and home, and lower when you are asleep or out. The physics is simple: a house loses heat faster the bigger the gap between indoors and outdoors. Every hour the house sits cooler, it loses less heat, so the furnace burns less fuel, even after the warm-up in the morning.

How much does turning the heat down save?

The Department of Energy estimates that setting the thermostat back 7 to 10°F for 8 hours a day can save up to about 10% a year on heating and cooling. Two 8-hour windows (sleeping and work) are easy to automate with any programmable or smart thermostat. The savings are larger in colder climates and leakier houses.

Making 68°F feel warmer

• Run ceiling fans clockwise on low: this pushes warm air from the ceiling down the walls without a cooling breeze.
• Add humidity if the air is very dry: dry air feels colder. Aim for 30 to 40% in cold weather (see humidity).
• Seal drafts around doors and windows, and close curtains at night.
• Check the filter: a clogged filter makes rooms far from the furnace cooler and can make the furnace short-cycle.

If the furnace runs but the house never reaches the setting, that is a heating problem, not a settings one: see the thermostat troubleshooting checklist.

3. Best thermostat setting in summer

For cooling, the Department of Energy suggests 78°F while you are home and a higher setting while you are out. Each degree warmer means less time with the compressor running, which is the biggest electrical load in most homes.

Ways to stay comfortable at 76–78°F

• Ceiling fans (counter-clockwise in summer) create a breeze that, according to the Department of Energy, lets you raise the thermostat about 4°F with no loss of comfort. Turn them off when you leave the room: fans cool people, not rooms.
• Keep humidity down. 76°F at 45% humidity feels better than 74°F at 65%. Leave the fan on Auto (see fan settings).
• Block the sun on east- and west-facing windows with blinds or curtains during the hottest hours.
• Don’t set it lower to cool faster. The AC cools at one speed; a 65°F setting just runs it longer.

Why your AC can’t reach the setting on very hot days

Central air conditioners are normally sized to hold a comfortable indoor temperature on a typical hot day for your area, not to pull the house far below the outdoor temperature. On record-heat days the indoor temperature can drift above the setting while the AC runs non-stop. Change the filter, hose dirt off the outdoor coil (power off), and keep the setting reasonable. If the AC runs but blows warm air, or the outdoor unit doesn’t start, see thermostat clicking but AC not turning on.

4. Best temperature for sleeping

Your body temperature drops at night, and a cool room helps that happen. Most sleep guidance suggests a bedroom of roughly 60 to 67°F, with about 65°F suiting most adults. That lines up neatly with an energy-saving winter setback.

• Start the sleep period early: about 30 minutes before bedtime, so the room is cool when you get into bed.
• End it before you get up: set the morning temperature 30 to 60 minutes before your alarm (smart thermostats learn this and start early on their own).
• Babies and older adults often need it warmer; many pediatric sources suggest roughly 68 to 72°F for an infant’s room. Dress for the room rather than overheating it.
• Summer nights: if you sleep well at 75 to 78°F with a fan, that saves the most; if not, comfort and sleep come first.

5. Away, vacation and pets

Out for the day

Set back 7 to 10°F: roughly 58 to 62°F in winter and 85 to 88°F in summer. Turning the setting up is usually better than switching the AC off in very hot or humid weather, because heat and moisture soak into furniture and walls and take a long time to remove.

Winter vacation

Don’t go below about 55°F. Pipes in outside walls, crawl spaces and under sinks can freeze long before the thermostat’s room gets that cold. Open cabinet doors under sinks on outside walls, and leave a key with someone in case the furnace fails. A smart thermostat’s low-temperature alert is worth turning on.

Summer vacation

85 to 88°F is fine for an empty house. In humid climates, stay nearer 82 to 85°F so the AC still runs often enough to remove moisture and prevent musty smells.

Pets

Dogs and cats handle a cooler house well in winter, but heat is riskier, especially for short-nosed breeds, older animals, birds and small pets. Many vets suggest not letting the house rise above about 80°F in summer with pets home alone. Ask your vet about your own animals.

Will the thermostat survive a power cut while you’re away?

Most smart thermostats keep their settings in memory and resume when power returns, but some systems need a reset. See thermostat not working after a power outage.

6. Thermostat fan setting: Auto vs On vs Circulate

The fan setting controls only the indoor blower, the fan in the furnace or air handler that pushes air through the ducts. It is wired to the G terminal (see the G wire).

• Auto: the blower runs only while the system heats or cools. Best for most homes, and especially for summer humidity: between cycles, water drips off the cold AC coil and drains away.
• On: the blower runs non-stop. Temperatures are more even between floors and rooms, and the filter cleans the air all day. The cost is electricity (much more with an older PSC blower motor than a modern ECM one) and, in summer, moisture: the fan blows over the wet coil and puts some water back into the air.
• Circulate (Honeywell, ecobee “fan minimum runtime” and similar): runs the fan for a set number of minutes each hour. The best of both for uneven houses or allergy season.

If the fan runs all the time even on Auto, check that the fan mode really is Auto and that the G wire is on the right terminal at both ends. Our thermostat wiring diagrams show where G goes.

7. Heat pump thermostat settings

Heat pumps are the main exception to “turn it down a lot at night”. A heat pump heats efficiently but slowly. After a deep setback, a thermostat that isn’t heat-pump-aware brings on auxiliary heat (usually electric heat strips) to catch up, and electric strips cost two to three times as much to run per unit of heat as the heat pump itself.

• Keep setbacks small: 2 to 4°F, or none at all in very cold weather.
• Use smart recovery: ecobee, Nest, Honeywell Home and other heat-pump-capable thermostats can start warming early using only the compressor.
• Set an aux heat lockout (often called the auxiliary heat max outdoor temperature) so heat strips don’t run on mild days.
• Leave emergency heat off unless the outdoor unit is broken. Emergency heat runs heat strips only. See aux heat vs. emergency heat.
• Set O/B correctly. If heat blows cold, the O/B setting is reversed; see the heat pump wiring guide.

If aux heat runs on every cycle, read heat pump aux heat running too much. Dual-fuel systems (heat pump plus gas furnace) also need a switchover temperature; the heat pump guide explains how to choose one.

8. Humidity settings

The EPA recommends keeping indoor humidity below 60%, ideally 30 to 50%. Above that, mold and dust mites thrive; below about 30% in winter, skin, eyes and wood floors dry out and static builds up.

• Summer: your AC is your dehumidifier. Fan on Auto, a clean filter, and an AC that isn’t oversized do most of the work. Some smart thermostats can also cool a degree or two below the setting to pull out extra moisture (ecobee calls this AC Overcool), or control a whole-house dehumidifier.
• Winter: a whole-house humidifier on the furnace can be controlled by a thermostat with accessory terminals (ecobee Premium’s ACC terminals, or Nest’s AQ terminals on supported models). Lower the target on very cold days to avoid condensation on windows.

9. Schedules, hold and smart features

Programmable schedules

A typical weekday schedule has four periods: Wake, Leave, Return and Sleep. Set the start of each period 30 minutes before you need it. Use a separate weekend schedule if your routine differs.

What “hold” means

• Temporary hold: you changed the temperature by hand; the thermostat keeps it until the next scheduled period, then returns to the schedule.
• Permanent hold (also “hold until I change it”): keeps that temperature indefinitely and ignores the schedule. It is the most common reason a programmable thermostat “stops saving money”.

Smart features worth turning on

• Away or geofencing modes that set back automatically when everyone’s phone leaves.
• Early start / smart recovery, so the house is comfortable at the scheduled time.
• Remote room sensors (ecobee, Honeywell T9) that average or prioritize the rooms you are actually in.
• Alerts for high or low temperatures and filter reminders.

ENERGY STAR puts the average saving of a certified smart thermostat at about 8% of heating and cooling costs. Compare models in our smart thermostat guides, and check your wiring first with the wiring tool.

Cycle rate and temperature swing

If the furnace or AC turns on and off too often, or the temperature swings too far, look for a cycle rate (cycles per hour) or temperature differential setting. Defaults match most equipment; mismatched settings (for example, a high cycle rate on a boiler) are covered in the settings to check after installing.

10. Where to put a thermostat

A thermostat measures the air right around it. In the wrong spot it reads too warm or too cold, and every setting in this guide is off by that much.

• Interior wall near the center of the house, in a room you use (a living area or main hallway with air movement).
• About 52 to 60 inches above the floor is common practice. Where accessibility matters, keep controls within reach of a seated person (ADA guidance limits reach to 48 inches).
• Away from direct sun, supply and return vents, exterior doors and windows, kitchens, lamps, TVs and bathrooms.
• Seal the wall hole behind the thermostat. Air from the wall cavity, attic or basement can be much colder or warmer than the room and fools the sensor.

Moving a thermostat means extending or replacing the cable. Use 18-gauge thermostat wire with a spare conductor or two; see thermostat wire gauge and running new wire.

11. How to reset a thermostat

“Reset” means three different things, from mildest to most drastic:

1. Restart (power cycle). Turn the HVAC system off at the furnace or air handler service switch or breaker for about 30 seconds, then back on. For battery thermostats, remove the batteries for the same time. This fixes most frozen screens and lost connections and keeps all your settings.
2. Reset the schedule only. Most thermostats let you clear the schedule without touching the equipment setup. Useful when holds and edits have piled up.
3. Factory reset. Nest, ecobee, Honeywell Home and most other smart thermostats have a reset option in their settings menu; check the manual for the exact path. This erases everything, including the equipment settings (furnace or heat pump, O/B, stages, aux heat). Note them before you reset and re-enter them carefully afterwards.

If the screen is blank and nothing responds, it isn’t a reset problem: there is no power. Check the furnace fuse, the panel door switch and the condensate float switch. See troubleshooting and testing thermostat wires with a multimeter. A smart thermostat that keeps rebooting usually needs a C wire: see the no C wire guide.

12. Thermostat myths that cost money

13. Frequently asked questions