What does a blood pressure of 120/80 mean?
A blood pressure of 120/80 means the pressure in your arteries rises to 120 mmHg when the heart squeezes, and falls to 80 mmHg while it refills. In the US, high blood pressure starts at 130/80 (stage 1, AHA/ACC 2025); in Europe, doctors use 140/90 in the office.
Simplified diagram for an adult. The situations show example values, not norms. Dashed curves are estimates.
What does a blood pressure of 120/80 mean?
It's the pressure of the blood in your arteries, in millimeters of mercury (mmHg): 120 when the heart squeezes, 80 while it refills.
Sources: thresholds from the AHA/ACC (Jones, 2025), the ESC (McEvoy, 2024) and France's HAS (2016); resting pulse of 60 to 100 (MedlinePlus); the aorta stiffening with age (Franklin, 1997; Pierce, 2022); the rise during exercise (Kosowski, 2024); the effect of stress (Steptoe, 2003). The 4 situations show example values, not norms, and the shape of the curves is schematic.
Keyboard: 1 to 4 the situation, Space pause, L slow motion, ← → frame by frame, Esc show everything.
Frequently asked questions about blood pressure
What is a normal blood pressure for your age?
Normal blood pressure doesn't depend on age in adults. In the US, high blood pressure starts at 130/80 mmHg (stage 1), and 120 to 129 with a bottom number under 80 is called “elevated” (AHA/ACC, 2025). In Europe, doctors speak of high blood pressure from 140/90 mmHg in the office, and in France from 135/85 when measured at home (HAS, 2016). What changes over the years is the trend. The top number slowly rises, because the large arteries get stiffer, and the bottom number often drops after age 50 to 60 (Franklin, 1997). The thresholds stay the same for all adults.
Why does blood pressure drop at night?
Blood pressure drops at night because the body goes into rest mode: the heart slows down and the small arteries relax. In most people, it falls by about 10 to 20% compared with the daytime, then rises again on waking (European Society of Hypertension, Parati, 2025). In some people, it drops only a little or not at all: this is more common with sleep apnea or kidney disease. Only a monitor worn for 24 hours can show it.
How do you measure your blood pressure correctly at home?
To measure your blood pressure correctly at home, France's health authority (HAS) recommends the “rule of 3”: 3 readings in the morning before breakfast and medications, 3 in the evening before bed, 3 days in a row (HAS, 2016). Sit down and rest a few minutes without talking, with your forearm on the table, using a validated upper arm monitor. Write down every reading for your doctor: in France, at home, high blood pressure starts at an average of 135/85.
Can you feel when your blood pressure is too high?
Most of the time, you can't feel high blood pressure: it usually causes no symptoms, and only a reading can catch it (WHO, 2025). According to the WHO, about 44% of adults aged 30 to 79 worldwide who have high blood pressure don't know it. Headaches, tiredness or a red face are not reliable signs. That's why it's worth having your blood pressure checked from time to time, even when you feel fine.
When should you worry about your blood pressure?
Call 911 right away if your blood pressure reaches 180/120 mmHg or higher with signs such as a severe headache, chest pain, shortness of breath, blurred vision, confusion or dizziness (WHO, 2025). Without these signs, readings that are often at or above 130/80 deserve a visit to your doctor (AHA/ACC, 2025); in Europe, the thresholds are 140/90 in the office and, in France, 135/85 at home (HAS, 2016). Never change a treatment on your own.
True or false?
The bottom blood pressure number always goes up with age.
False. The top number rises with age, but the bottom one rises until about age 50 to 60, then goes back down (Franklin, 1997).
Eating less salt lowers blood pressure.
True. Across 34 trials and 3,230 people, 4.4 g less salt a day lowered blood pressure by about 4 mmHg on top and 2 mmHg on the bottom (He, 2013).
Blood pressure going up during exercise is abnormal.
False. The top number normally rises with exercise intensity. A rise is called excessive above about 210 mmHg in men and 190 mmHg in women (Patel, 2024; Petrasch, 2025).
This page as text
The same information as the charts, to read without animation: for each chart, the values at the main moments, then the notes with their level of evidence.
What happens in the artery with each heartbeat?
At rest, the heart beats 60 to 100 times a minute. With each contraction, the pressure in the aorta rises to the top number (here 120 mmHg). While the heart refills, it falls back to the bottom number (here 80), without ever dropping to zero.
| Time | Pressure in the aorta | Pressure in the left ventricle (dotted) | What happens |
|---|---|---|---|
| 0 s | 40 | 4 | aorta at 81 mmHg, the heart is squeezing |
| 1 s | 59 | 60 | aorta at 118 mmHg, the heart is squeezing |
| 2 s | 57 | 58 | aorta at 115 mmHg, the heart is squeezing |
| 3 s | 51 | 3 | aorta at 103 mmHg, the heart is refilling |
| 4 s | 45 | 4 | aorta at 91 mmHg, the heart is refilling |
Key points
- Systole: the heart pushes (Throughout, Shown in humans)
The left ventricle contracts. When its pressure rises above the pressure in the aorta, the valve opens and the blood leaves: the pressure in the artery rises to the top number. Source: StatPearls, Pollock and Makaryus, « Physiology, Cardiac Cycle », 2022 - The valve closes (Throughout, Shown in humans)
When the heart relaxes, the aortic valve closes: a small notch appears on the aorta curve, and the pressure inside the heart drops almost to zero. Source: StatPearls, Pollock and Makaryus, « Physiology, Cardiac Cycle », 2022 - Diastole: the aorta takes over (Throughout, Shown in humans)
The elastic wall of the aorta, stretched by the heartbeat, springs back and keeps pushing the blood. The pressure slowly drops to the bottom number. Source: Pierce et al., « Is It Good to Have a Stiff Aorta with Aging? Causes and Consequences », Physiology, 2022 - 120/80 mmHg: what the units mean (Throughout, Hypothesis)
Blood pressure is written in millimeters of mercury: 120/80 mmHg. The first number is the peak while the heart squeezes (systolic), the second the low point while it refills (diastolic). The shape of the curves is schematic.
Why does blood pressure go up during exercise?
During exercise, the heart beats faster and pumps more blood with each beat. The top number rises with the intensity; the bottom number changes little, or drops a bit.
| Time | At rest (120/80) (dotted) | During exercise (example: 160/70) | What happens |
|---|---|---|---|
| 0 s | 40 | 38 | at rest 81 mmHg, during exercise 76 mmHg |
| 1 s | 59 | 80 | at rest 118 mmHg, during exercise 160 mmHg |
| 2 s | 57 | 66 | at rest 115 mmHg, during exercise 133 mmHg |
| 3 s | 51 | 38 | at rest 103 mmHg, during exercise 76 mmHg |
| 4 s | 45 | 80 | at rest 91 mmHg, during exercise 160 mmHg |
Key points
- The top number rises with intensity (Throughout, Shown in humans)
In a healthy person, the top number rises gradually with the intensity of exercise, while the bottom number changes little or drops a bit. Source: Kosowski et al., « Hypertensive Response to Exercise as an Early Marker of Disease Development », Biomedicines, 2024 - When the rise is considered excessive (Throughout, Shown in humans)
In studies, a rise is often called excessive above about 210 mmHg in men and 190 in women, at peak exercise. Source: Petrasch et al., « Definitions for hypertensive response to exercise: a systematic review », Minerva Med, 2025 - Example values (Throughout, Hypothesis)
160/70 is an example, not a norm: the rise depends on the effort, age and fitness. It comes back down after exercise.
Why does the top number go up with age?
Over the years, the large arteries lose their elasticity. They cushion each heartbeat less: the top number rises, the bottom number tends to drop after age 50 to 60, and the gap between the two widens.
| Time | Elastic artery (120/80) | Stiff artery (example: 150/70) | What happens |
|---|---|---|---|
| 0 s | 40 | 35 | elastic artery 81 mmHg, stiff artery 70 mmHg |
| 1 s | 59 | 75 | elastic artery 118 mmHg, stiff artery 149 mmHg |
| 2 s | 57 | 69 | elastic artery 115 mmHg, stiff artery 138 mmHg |
| 3 s | 51 | 53 | elastic artery 103 mmHg, stiff artery 107 mmHg |
| 4 s | 45 | 40 | elastic artery 91 mmHg, stiff artery 81 mmHg |
Key points
- What the Framingham study shows (Throughout, Shown in humans)
In this large American study, the top number rises steadily from age 30 to 84; the bottom number rises until about age 50 to 60, then drops. Source: Franklin et al., « Hemodynamic patterns of age-related changes in blood pressure. The Framingham Heart Study », Circulation, 1997 - An aorta twice as stiff (Throughout, Shown in humans)
Over a lifetime, the stiffness of the aorta more than doubles: the elastic fibers wear out, and stiffer collagen fibers carry the load. Source: Pierce et al., « Is It Good to Have a Stiff Aorta with Aging? Causes and Consequences », Physiology, 2022 - Salt, over time (Throughout, Shown in humans)
Eating less salt lowers blood pressure: on average by 4 mmHg for the top number and 2 for the bottom number, with about 4.4 g less salt a day (34 trials, 3,230 people). Source: He, Li and MacGregor, « Effect of longer term modest salt reduction on blood pressure », BMJ, 2013 - One person in three (Throughout, Shown in humans)
In France, about 31% of adults aged 18 to 74 have high blood pressure, and only 24% of them have it well controlled (Esteban study, measurements from 2015). Source: Vallée et al., « Patterns of hypertension management in France in 2015: The ESTEBAN survey », J Clin Hypertens, 2020 - Schematic curves (Throughout, Hypothesis)
The two shapes are drawn for comparison: a higher, sharper peak and a faster drop when the artery is stiff.
How does the cuff measure blood pressure?
The cuff squeezes the arm harder than the top number: blood can no longer get through. Then it is slowly deflated. When its pressure drops below the top number, blood squirts through in spurts and makes a sound in the stethoscope: that is the first number. When the sound disappears, that is the second.
| Time | Pressure in the cuff | Pressure in the arm artery | What happens |
|---|---|---|---|
| 0 s | 80 | 40 | cuff at 160 mmHg, no blood gets through |
| 5 s | 72 | 42 | cuff at 145 mmHg, no blood gets through |
| 10 s | 65 | 45 | cuff at 130 mmHg, no blood gets through |
| 15 s | 58 | 51 | cuff at 115 mmHg, you hear the beats |
| 20 s | 50 | 57 | cuff at 100 mmHg, you hear the beats |
| 25 s | 42 | 59 | cuff at 85 mmHg, you hear the beats |
| 30 s | 35 | 40 | cuff at 70 mmHg, blood flows silently |
Key points
- First sound: the top number (From 13.2 to 13.6 s, Shown in humans)
As soon as the cuff drops below the peak pressure, a little blood gets through with each beat: you hear a beat in the stethoscope. This first Korotkoff sound (phase I) gives the top number. Source: Pickering et al., « Recommendations for blood pressure measurement in humans and experimental animals: part 1 », Circulation, 2005 - The sound disappears: the bottom number (From 26.5 to 27 s, Shown in humans)
When the cuff drops below the lowest pressure, blood flows smoothly and the sound stops. The last sound heard (phase V) gives the bottom number. Source: Pickering et al., « Recommendations for blood pressure measurement in humans and experimental animals: part 1 », Circulation, 2005 - Deflate slowly (Throughout, Shown in humans)
Here 3 mmHg per second: the advice is 2 to 3 mmHg per second. Too fast, and you miss the right number. Source: Pickering et al., « Recommendations for blood pressure measurement in humans and experimental animals: part 1 », Circulation, 2005 - Home monitors (Throughout, Shown in humans)
France's health authority (HAS) recommends a validated monitor, preferably with an upper-arm cuff. Source: HAS and SFHTA (France), fact sheet « Prise en charge de l'hypertension artérielle de l'adulte », 2016 - A monitor that doesn't listen (Throughout, Shown in humans)
Electronic monitors don't use the sounds: a sensor measures the small pressure swings that each heartbeat creates in the cuff, and a calculation turns them into the two numbers. Source: Babbs, « Oscillometric measurement of systolic and diastolic blood pressures validated in a physiologic mathematical model », Biomed Eng Online, 2012
Does blood pressure drop at night?
Yes, usually: during sleep, blood pressure drops by about 10 to 20% compared with the daytime, then rises again on waking. Both curves are estimates.
| Time | Top number (estimate) (dotted) | Bottom number (estimate) (dotted) | What happens |
|---|---|---|---|
| 0:00 | 53 | 34 | 106/68 mmHg (estimate) |
| 4:00 | 53 | 34 | 106/68 mmHg (estimate) |
| 8:00 | 65 | 41 | 130/83 mmHg (estimate) |
| 12:00 | 62 | 40 | 125/80 mmHg (estimate) |
| 16:00 | 62 | 40 | 125/80 mmHg (estimate) |
| 20:00 | 62 | 40 | 125/80 mmHg (estimate) |
| 0:00 | 54 | 35 | 108/69 mmHg (estimate) |
Key points
- A 10 to 20% drop at night (From 0:00 to 7:00, Shown in humans)
In most people, nighttime blood pressure is 10 to 20% lower than daytime blood pressure. The heart slows down and the small arteries relax. Source: Parati et al., « Nocturnal blood pressure: pathophysiology, measurement and clinical implications. Position paper of the European Society of Hypertension », J Hypertens, 2025 - When it does not drop (All day, Shown in humans)
In some people, blood pressure drops little or not at all at night. This is more common with sleep apnea or kidney disease. Source: Parati et al., « Nocturnal blood pressure: pathophysiology, measurement and clinical implications. Position paper of the European Society of Hypertension », J Hypertens, 2025 - From one night to the next (All day, Shown in humans)
The nighttime drop varies from one night to the next in the same person: a single 24-hour reading is not always enough. Source: Asayama, Satoh and Kikuya, « Diurnal blood pressure changes », Hypertens Res, 2018 - Morning rise (From 6:00 to 10:00, Hypothesis)
Blood pressure rises again on waking. The small peak drawn here is an estimate.
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