The five vital signs routinely measured in clinical settings are body temperature, heart rate (pulse), respiration rate, blood pressure, and oxygen saturation. Together, these numbers give a quick snapshot of how well your body’s most essential functions are working. Any significant change in one or more can signal that something needs attention.
Body Temperature
The average normal body temperature is generally accepted as 98.6°F (37°C), but healthy readings can range from 97°F to 99°F (36.1°C to 37.2°C). Your temperature fluctuates throughout the day, typically running lowest in the early morning and peaking in the late afternoon. Exercise, hot weather, heavy clothing, and hormonal changes (like ovulation or menstruation) can all push it slightly higher without anything being wrong.
A temperature of 100.4°F (38°C) or above is generally considered a fever. Fevers are not an illness on their own. They’re a sign your immune system is responding to an infection or inflammation. On the other end, a body temperature that drops below 95°F (35°C) is classified as hypothermia, which can become dangerous quickly, especially in older adults or young children.
Heart Rate (Pulse)
A normal resting heart rate for adults is 60 to 100 beats per minute (bpm). If you’re physically active or an endurance athlete, your resting rate may sit in the 40s or 50s, which reflects a more efficient heart rather than a problem. Children’s hearts beat faster: newborns range from 100 to 205 bpm, toddlers from 98 to 140 bpm, and school-age kids from 75 to 118 bpm. By adolescence, the range matches the adult norm of 60 to 100.
Your pulse tells more than just speed. When a healthcare provider checks it, they’re also noting whether the rhythm is regular or irregular and whether the pulse feels strong or weak. Caffeine, stress, dehydration, and certain medications can all temporarily raise your heart rate. A consistently elevated resting heart rate, or one that’s irregular when you’re calm and rested, is worth mentioning to a provider.
Respiration Rate
A normal breathing rate for a resting adult is 12 to 18 breaths per minute. Most people never think about how fast they breathe because it’s controlled automatically, which is partly why it’s such a useful clinical indicator. A rate below 12 or above 25 breaths per minute at rest can point to an underlying health condition, from anxiety or pain on the milder end to pneumonia, asthma flare-ups, or metabolic problems on the more serious end.
Respiration rate is also one of the most telling signs when a hospitalized patient is getting worse. Research on trends in vital signs found that tracking changes in breathing rate over time significantly improved the ability to predict serious events in patients, more so than looking at a single snapshot reading. In practical terms, a gradually climbing breathing rate is one of the earliest red flags that something is shifting.
Blood Pressure
Blood pressure is recorded as two numbers: systolic (the pressure when your heart pumps) over diastolic (the pressure when it rests between beats). The 2025 guidelines from the American Heart Association and American College of Cardiology classify adult blood pressure into four categories:
- Normal: below 120/80 mmHg
- Elevated: 120 to 129 systolic with diastolic still below 80
- Stage 1 hypertension: 130 to 139 systolic or 80 to 89 diastolic
- Stage 2 hypertension: 140 or higher systolic, or 90 or higher diastolic
A single high reading doesn’t necessarily mean you have hypertension. Blood pressure responds to stress, caffeine, a full bladder, and even body position. Research from the American Physiological Society found that blood pressure and heart rate are generally higher when sitting compared to lying down, because of differences in how your nervous system activates in each position. That’s why providers often ask you to sit quietly for a few minutes before taking a reading, and why a diagnosis of high blood pressure is based on an average of multiple measurements rather than one number.
Oxygen Saturation
Oxygen saturation, often written as SpO2, measures the percentage of your red blood cells that are carrying oxygen. It’s checked with a pulse oximeter, a small clip placed on your fingertip that uses light to estimate the reading. For most people, a normal level falls between 95% and 100%.
A reading of 92% or lower is a reason to contact a healthcare provider. At 88% or below, it’s an emergency. People with chronic lung conditions like COPD may have a slightly lower baseline that their provider considers acceptable, but for the general population, consistently low oxygen saturation means tissues aren’t getting the oxygen they need to function.
Pulse oximeters became household items during the COVID-19 pandemic, and they’re useful tools, but they have limitations. Cold fingers, dark nail polish, and poor circulation can all produce inaccurate readings. If a reading seems unexpectedly low and you feel fine, warm your hands, remove nail polish, and try again before drawing conclusions.
Why Trends Matter More Than Single Readings
Any one vital sign measurement is a snapshot. What makes vital signs truly valuable is the pattern they form over time. A blood pressure of 135/85 means something different if your usual reading is 115/70 than if you’ve hovered around 130/82 for years. The same applies to heart rate, temperature, and breathing rate.
In hospital settings, predictive models that incorporate how vital signs change over hours perform significantly better than those using a single set of numbers. One study found that the accuracy of predicting serious events jumped from 85% to 93% when the model used readings taken closer to the event, and improved further when trends in breathing rate were added. For people monitoring their health at home, the takeaway is practical: tracking your numbers over weeks and months gives you and your provider far more useful information than any single reading on its own.