The ideal indoor temperature for most people falls between 68°F and 72°F (20°C to 22°C) during waking hours. That range keeps roughly 80% of occupants comfortable, according to ASHRAE Standard 55, the most widely referenced guideline for indoor thermal comfort. But the best setting for your home shifts depending on what you’re doing, who lives there, and what season it is.
The General Comfort Range
ASHRAE, the organization that sets building environment standards in the U.S., defines a “satisfactory thermal environment” as one where more than 80% of people find conditions acceptable. In field studies of real buildings, that threshold is met when indoor conditions fall within a relatively narrow band, typically 68°F to 76°F (20°C to 24°C) depending on clothing, activity level, and humidity. Most people in typical indoor clothing land comfortably around 70°F to 72°F.
Temperature is only half the equation. Humidity plays a major role in how warm or cool a room actually feels. The optimal range for indoor relative humidity is 30% to 50% year-round. In winter, when heating systems dry the air, aim for at least 30% to 40%. In summer, keeping humidity below 45% prevents that sticky, clammy feeling even when the thermostat reads a reasonable number. A room at 74°F with 60% humidity will feel noticeably warmer and less comfortable than the same room at 45% humidity.
Best Temperature for Sleep
Your body needs to cool down slightly to fall and stay asleep, which is why bedrooms should be cooler than the rest of your home. Sleep specialists at the Cleveland Clinic recommend keeping the bedroom between 60°F and 67°F (15°C to 19°C). Anything above 70°F is considered too hot, and below 60°F is too cold.
This cooler range matters because body temperature regulation is closely tied to sleep quality. Heat is a major disruptor of REM sleep, the stage where dreaming occurs and memory consolidation happens. Too much warmth or cold exposure increases wakefulness and reduces the time you spend in both REM and deep, restorative slow-wave sleep. If you tend to sleep hot, staying closer to the 60°F to 65°F end of the range can make a real difference in how rested you feel.
Temperature for Focus and Productivity
If you work from home or are setting up a home office, the temperature sweet spot for cognitive performance is a bit more specific than general comfort. A systematic review of 17 studies found that the optimal range for mental performance falls between 72°F and 75°F (22°C to 24°C). Above 75°F, reaction time and processing speed start to decline. Interestingly, higher-level thinking like logical reasoning holds up better in the heat than quick, reactive tasks do.
This means the temperature that feels “fine” might still be quietly dragging down your productivity. If your home office feels warm on summer afternoons and you notice yourself slowing down, the thermostat is a good first thing to check.
Recommended Settings by Season
The U.S. Department of Energy recommends setting your thermostat to 68°F to 70°F while you’re awake during winter, then lowering it while you’re asleep or away from home. Every degree you lower the thermostat for an extended stretch saves energy without requiring much sacrifice in comfort, especially under blankets at night.
In summer, the strategy flips: keep the house warmer than you normally would when you’re away, and set the thermostat to the highest comfortable temperature when you’re home. For most people, that lands around 76°F to 78°F with a ceiling fan running. The goal is to minimize the gap between indoor and outdoor temperatures, which is where cooling costs climb fastest.
Safe Temperatures for Older Adults
Older adults are more vulnerable to indoor cold than most people realize. The National Institute on Aging warns that even mildly cool homes, in the 60°F to 65°F range, can lead to hypothermia in seniors. Their recommendation is to keep the heat at a minimum of 68°F.
The health risks of cold indoor air go beyond discomfort. Cold air inflames the lungs and restricts blood circulation, raising the risk of respiratory infections, asthma flare-ups, and worsening of chronic lung disease. It also stresses the cardiovascular system. Scottish cohort studies found that people living in homes heated below 64°F (18°C) had a significantly higher risk of elevated blood pressure, and that risk jumped nearly fivefold when temperatures dropped below 61°F (16°C). The World Health Organization has proposed 64°F (18°C) as the minimum safe indoor temperature for general populations in cold climates, but for older adults or anyone with heart or lung conditions, 68°F is the safer floor.
Keeping Infants Comfortable and Safe
For nurseries, the concern is overheating rather than cold. The American Academy of Pediatrics lists overheating as a risk factor for sleep-related infant deaths, though it stops short of naming a specific temperature because studies have defined “overheating” differently. The practical guidance is to keep the nursery at the same temperature that feels comfortable for a lightly clothed adult, generally 68°F to 72°F, and dress the baby in no more than one layer beyond what you’d wear yourself.
Skip hats indoors after the first hours of life, avoid heavy bundling, and keep the baby’s face and head uncovered during sleep. If you’re unsure whether the room is too warm, touch the back of the baby’s neck or stomach. Sweating or skin that feels hot to the touch means it’s time to remove a layer or lower the thermostat.
Quick Reference by Activity
- Daytime living spaces: 68°F to 72°F (20°C to 22°C)
- Sleeping: 60°F to 67°F (15°C to 19°C)
- Home office or focused work: 72°F to 75°F (22°C to 24°C)
- Homes with older adults: no lower than 68°F (20°C)
- Nurseries: 68°F to 72°F (20°C to 22°C)
Pair any of these with indoor humidity between 30% and 50%, and you’ll cover both comfort and health for nearly every situation in a typical home.