We are often told that the normal body temperature for adults is around 98.6 degrees Fahrenheit or 37 degrees Celsius.
This means that if you’re taking your temperature at home with a thermometer, you might think that any body temperature above 98.6°F for an adult would be considered “having a fever.”
Conversely, having a body temperature below 98.6°F or above 37°C might be considered abnormally low.
But, is this true? What is a good body temperature for adults?
In this guide to a good body temperature in adults, we will discuss the average adult body temperature, factors that affect body temperature, and what is considered a good body temperature.
Let’s dive in!
What Is A Good Body Temperature for Adults?
If you wear a body tracker device like an Oura ring or you take your temperature with a thermometer with some amount of regularity, you might notice that your temperature is consistently below the “normal“ 98.6°F.
This is why many people ask questions like: “Is it normal to have a temperature of 97.5 degrees? Does a temperature below 98° mean you have hypothyroid issues?”
So, what is a healthy and good body temperature for adults?
Although the commonly tossed around “average adult body temperature“ is 98.6°F or about 37°C, Dr. Stacie Barber, a Physical Therapist, Strength Coach, and Hyperice Performance Advisor1Hyperice. (n.d.). Hyperice.com. https://hyperice.com/ says that individual body temperatures can vary, and there’s actually a range within which you are still considered to have normal body temperature even if you are not at exactly 98.6°F.
“A good body temperature can range anywhere from 97.8°F (36.5°C) to 99.1°F (37.3°C) and still be within the normal range,” explains Dr. Barber. “What’s normal for one person may not be the same for another.”
Furthermore, there is some relatively recent research to suggest that the average adult body temperature might be dropping.
“The value of 98.6 degrees Fahrenheit has long been considered the average body temperature,” says Dr. Barber.
“However, a new study by Stanford Medicine scientists found that the average body temperature is dropping every decade, and may actually be closer to 97.9°F (36.5°C) these days.”2Ley, C., Heath, F., Hastie, T., Gao, Z., Protsiv, M., & Parsonnet, J. (2023). Defining Usual Oral Temperature Ranges in Outpatients Using an Unsupervised Learning Algorithm. JAMA Internal Medicine, 183(10), 1128–1135. https://doi.org/10.1001/jamainternmed.2023.4291
Factors That Affect What Is Considered a Normal Body Temperature
In addition to the findings that the average body temperature for men and women might be dropping across the spectrum, the research published by the Stanford scientists confirmed that there are several factors that can influence an individual’s body temperature.3nina.bai @stanford.edu, img src=’https://med stanford edu/news/media-contacts/nina-bai/_jcr_content/image img 620 high jpg/Nina-Bai2 jpg’ alt=’Nina B. N. B. N. B. is a science writer in the O. of C. E. her at. (2020, January 7). Normal body temperature is personal, Stanford Medicine researchers find. News Center. https://med.stanford.edu/news/all-news/2023/09/body-temperature.html
Here are some of the factors that can affect what might be considered a “normal“ or good adult body temperature:
#1: Time of Day
The research looked at how body temperature changes based on the time of day and found that it is normal for your body temperature to fluctuate throughout the day.
Generally, body temperature is slightly lower in the morning and peaks at your highest body temperature around 4 PM for most individuals.
#2: Demographics
The research also found that various demographics can influence your body temperature as well, namely age, height, sex, and body weight.
Generally, the following trends are seen in average body temperatures:
Average body temperature decreases with age so seniors will have a lower normal body temperature than young adults, and certainly lower than children.
The study found that older, shorter males had slightly lower average temperatures than heavier individuals, and women had higher average temperatures.
#3: Health Status
“Stanford Scientists also found that health status and health conditions can also affect our body temperature,” explains Dr. Barber.
“For example, infectious diseases are linked to an increase in body temperature, and type 2 diabetes is linked to a decrease in body temperature.”
Does Body Temperature Change With the Menstrual Cycle?
In addition to factors like age, time of day, and health status, the daily body temperature for females can be affected by the hormonal balance based on the stage of the menstrual cycle the woman is in.4Baker, F. C., Siboza, F., & Fuller, A. (2020). Temperature regulation in women: Effects of the menstrual cycle. Temperature, 7(3), 1–37. https://doi.org/10.1080/23328940.2020.1735927
“During the follicular phase, which is the first half of the cycle (which takes you from menstruation to ovulation) basal body temperature (BBT) lies somewhere between 97.0 and 97.6 degrees Fahrenheit,” notes Dr. Barber.
“There can be a slight detectable dip in BBT just prior to ovulation, but about 24 hours post-ovulation is when the most significant shift happens.”
Dr. Barber explains that this predictable change in body temperature in the menstrual cycle marks the transition into the luteal phase, where progesterone takes over as the dominant female reproductive hormone, and we see a spike in the average body temperature.
“Progesterone is a catabolic hormone, increasing a woman’s metabolic rate by up to 300 calories per day,” explains Dr. Barber.
“All of that extra heat is reflected in basal body temperature, which rises by up to an entire degree. Typical luteal phase readings are between 97.6 – 98.6 degrees F.”
Dr. Barber says that this elevation in body temperature for women during the second half of the menstrual cycle can cause some to feel more sensitive to certain climates during exercise (particularly when exercising in hot environments), but it does not decrease exercise performance.
“As the luteal phase comes to an end, basal body temperature drops again and menstruation begins,” says Dr. Barber. “This biomarker is a key component to how many women practice the sympto-thermal method for natural birth control.”
It is also how many women who are looking to get pregnant track their ovulation to optimize the fertility window.
Conversely, rather than considering how the menstrual cycle affects daily body temperature for a woman, Dr. Barber says that there can also be value in looking at daily fluctuations in body temperature (or lack thereof) in females as a biomarker of reproductive health.
“According to Courtney Babilya, a women’s fitness nurse, your basal body temperature (BBT), or the lowest temperature your body reaches at complete rest, is a major biomarker for menstrual health,” suggests Dr. Barber.
Note that this only applies to premenopausal women.
We know that there should be slight fluctuations in your average body temperature per day based on the phase of the menstrual cycle.
But if your body temperature is not cycling in the predicted pattern in a time course that should line up with the 28 to 30-day menstrual cycle (more or less), there may be underlying issues with your reproductive hormones.
“It’s important to note that a BBT reading requires a very specific technique for accurate results (and wearable overnight devices have made this process seamless), so taking your temperature at random cannot assess your menstrual phase or menstrual health,” warns Dr. Barber.
”Certain things can prevent a significant BBT rise, such as anovulatory cycles, hypothyroidism, or stress.”
Does Average Body Temperature Differ Between Men and Women?
“Sex can have a minor influence on body temperature, with some studies suggesting that, on average, women may have slightly higher core body temperatures than men,” explains Dr. Barber.
“However, the difference is generally small and not clinically significant.”
Instead of sex, Dr. Barber says that other factors such as your age, activity level, and overall health status have a more significant impact on average body temperature
As Dr. Barber notes:
“It’s important to remember that normal body temperature can vary among individuals, and these variations are more related to individual differences rather than gender-specific characteristics.”
Is a Low Body Temperature Bad?
According to the Mayo Clinic, consistently having a body temperature that is lower than 95 degrees Fahrenheit can be a sign of various underlying medical conditions or factors.
Dr. Barber provides some of the possible reasons for a consistently lower-than-average body temperature including:
#1: Hypothyroidism
A condition where the thyroid gland produces insufficient amounts of key thyroid hormones, which can lead to a slowed metabolism and lower body temperature.
#2: Exposure to Cold Environments
Dr. Barber says that prolonged exposure to cold temperatures can lower your body temperature due to excessive heat loss. This risk is more common in individuals who work in cold conditions or live in cold climates.
#3: Aging
Older adults may have slightly lower average body temperatures than younger adults and children.
#4: Poor Circulation
Circulatory problems or conditions that affect blood flow can result in lower body temperatures.
#5: Nervous System Disorders
The hypothalamus (brain region) helps to regulate body temperature.
Dr. Barber says that conditions such as stroke, spinal cord injury, Parkinson’s disease, or multiple sclerosis, which may affect the function of the hypothalamus or brain/nervous system functioning can lead to lower body temperatures.
#6: Hormonal Imbalances
Hormonal disorders or imbalances can impact body temperature, and low body temperatures may be a sign that you have a hormonal problem.
#7: Infection
Chronic or severe infections can potentially lower body temperatures.
“If you consistently experience low body temperature and are concerned about it, it’s important to consult with a healthcare professional for a thorough evaluation,” advises Dr. Barber.
“They can help determine the underlying cause and recommend appropriate treatment or lifestyle adjustments.”
