What Temperature Should I Set My Thermostat in Summer?

What temperature should I set my thermostat in summer?

The U.S. Department of Energy recommends setting your thermostat to 78°F (26°C) in summer when you're home and awake. When you're away or asleep, raising it by 7–10°F can cut your cooling costs by up to 10% a year without sacrificing comfort while you're actually home.

That single number surprises people who keep their house at 72°F - but here's why 78°F is the sweet spot, and how to stay comfortable at it.

Quick takeaways:

• Home and awake: 78°F (the DOE-recommended setting)
• Away from home: 85–88°F
• Sleeping: 82°F, or whatever lets you sleep
• Each degree lower can add roughly 3% to your cooling bill
• A programmable or smart thermostat captures these savings automatically

The recommended summer thermostat schedule

The bigger the gap between your "home" and "away" settings - and the longer you hold the setback - the more you save. The savings come from your AC simply running less while no one's there to notice.

Why every degree matters

For every degree you lower the thermostat below 78°F, your air conditioner works harder and longer, adding roughly 3% to your cooling costs. Set the house to 72°F instead of 78°F and you can be paying 15–20% more to cool it. Nudging the setting up a few degrees is the single cheapest way to lower a summer electric bill.

How to stay comfortable at 78°F

• Run ceiling fans. Moving air makes a room feel about 4°F cooler, so a fan plus 78°F feels like 74°F. (Turn fans off when you leave - they cool people, not rooms.)
• Close blinds on sunny windows to block solar heat gain.
• Lower indoor humidity. Dry air at 78°F feels far more comfortable than humid air. A properly sized, well-maintained AC dehumidifies as it cools - an oversized unit that short-cycles leaves the air clammy.
• Use the setback while you sleep and work rather than cooling an empty or sleeping house to daytime temps.

Let a smart thermostat do it for you

The easiest way to hit these numbers is to stop thinking about them. A programmable or smart thermostat (Nest, Ecobee, Honeywell) runs the schedule automatically and uses geofencing to ease off when you leave. Most homes cut heating and cooling use 8–15% this way - see our smart thermostat installation guide, or our thermostat troubleshooting guide if yours is acting up.

A note on not going too low

Cranking the AC to 65°F on a 95°F day doesn't cool the house faster - your AC cools at a fixed rate regardless of the setpoint. All a very low setting does is make the system run longer and risk freezing the coil. Set it where you want it and let it get there.

Bottom line

Set your thermostat to 78°F when you're home, bump it to 85–88°F when you're out, and 82°F overnight. Pair it with ceiling fans and closed blinds, and you'll stay comfortable while trimming your cooling bill by up to 10% - automatically, if you let a smart thermostat run the schedule.

Want a smart thermostat installed and dialed in? Connect with a licensed local pro - Nest, Ecobee, and Honeywell, same-day appointments.