What Is a Normal Blood Pressure? A Plain Guide with Chart

For most adults, a normal blood pressure is below 120/80 mmHg. Readings between 120–139 over 80–89 are raised, and 140/90 or above, measured consistently on separate days, is generally treated as high blood pressure.

Blood pressure is one of the few things about your health you can measure in two minutes, for free, without any symptoms to prompt you. This guide explains what the numbers mean, how to get a reading you can trust, and when a number is an emergency.

What the two numbers mean

A reading is always given as two numbers, for instance 118/76 mmHg.

• The top number is systolic pressure, the pressure in your arteries while the heart is contracting and pushing blood out. It is the higher of the two.
• The bottom number is diastolic pressure, the pressure while the heart is relaxed and filling between beats.

“mmHg” stands for millimetres of mercury, a unit inherited from the original mercury instruments. Both numbers matter. Either one being consistently high is enough to be classed as high blood pressure.

Blood pressure chart

Thresholds vary slightly between guidelines, and some newer classifications set the bar lower. For everyday purposes the practical points are these: below 120/80 is where you want to be, 140/90 and above needs a doctor’s attention, and 180/120 and above needs a hospital today.

If you have diabetes or kidney disease, your doctor may set a lower personal target. Follow their advice over any general chart, including this one.

Why one high reading is not a diagnosis

Blood pressure is not a fixed number. It moves constantly, and it rises with:

• physical activity, including hurrying to the appointment
• stress, anxiety or anger
• caffeine and cigarettes
• pain
• a full bladder
• talking during the measurement
• cold temperatures
• simply being in a clinical setting, common enough that it has a name, “white coat hypertension”

This is why one raised reading on one day proves very little, and why a diagnosis of hypertension is based on a pattern across several readings taken on different days. It is also why free, repeatable checks are more useful than a single paid measurement once a year.

How to get an accurate reading

Small details change the number more than most people expect:

1. Rest for five minutes first. Sit quietly. Do not measure immediately after walking in.
2. Avoid caffeine and cigarettes for 30 minutes beforehand.
3. Empty your bladder. A full bladder can raise systolic pressure noticeably.
4. Sit properly, back supported, feet flat on the floor, legs uncrossed.
5. Support your arm at roughly heart height. An unsupported or low arm gives a higher reading.
6. Use the right cuff size. A cuff too small for the arm reads falsely high. This is one of the most common measurement errors.
7. Do not talk during the measurement.
8. Take two or three readings a minute apart and use the average.

If you measure at home, do it at the same times each day, typically morning before medication and evening, and write the numbers down. A record over weeks is worth far more to a doctor than a single number on the day.

Low blood pressure

Readings below 90/60 mmHg are generally considered low. For many people, particularly younger and physically active ones, this is simply normal and causes no problems at all.

It matters when it produces symptoms: dizziness or light-headedness, especially on standing, fainting, blurred vision, unusual fatigue, nausea or difficulty concentrating. Low pressure that appears suddenly, or comes with these symptoms, should be discussed with a doctor, it can point to dehydration, blood loss, infection, or a medication effect.

Why high blood pressure matters so much

Hypertension causes no symptoms in most people until it has already caused damage. That is the entire difficulty with it. Left untreated over years, sustained high pressure raises the risk of:

• Stroke, one of the leading causes of death and long-term disability in Kenya
• Heart attack and heart failure
• Kidney damage, up to and including kidney failure
• Vision loss, through damage to the small blood vessels of the retina
• Cognitive decline in later life

None of this announces itself in advance. Regular measurement is the only early warning available.

When a headache is not just a headache

There is a persistent belief that high blood pressure causes headaches, and that you will feel it when it is high. For ordinary hypertension, that is not true, and believing it is dangerous , it leads people to skip medication on days they feel fine.

Very high pressure, however, can cause symptoms. Seek urgent medical care if a reading of 180/120 or above comes with:

• severe headache
• chest pain
• shortness of breath
• visual changes
• weakness or numbness on one side of the body
• difficulty speaking

Those combinations may indicate a hypertensive emergency, a stroke or a cardiac event. Go to a hospital.

What actually lowers blood pressure

The interventions with the best evidence are unglamorous and mostly free:

Reduce salt. This is the single highest-impact dietary change for most people. The bulk of it is not the salt shaker but processed foods, stock cubes, packet soups and preserved meats. Cutting back has a measurable effect within weeks.

Lose excess weight. Even a modest loss produces a meaningful drop in blood pressure.

Move regularly. Around 30 minutes of brisk walking most days is enough to matter. It does not require a gym.

Cut down on alcohol. Heavy drinking raises blood pressure directly and reliably.

Stop smoking. Each cigarette raises pressure temporarily, and smoking damages arteries over the long term. Quitting improves cardiovascular risk faster than most people expect.

Eat more fruit and vegetables. Potassium-rich foods help offset sodium.

Manage stress and sleep. Poor sleep and untreated sleep apnoea both raise blood pressure.

If you have been prescribed medication, take it every day, including on days you feel well. Hypertension does not signal its return. Stopping because you feel fine is the most common reason treatment fails, and it is entirely avoidable.

Who should check, and how often

Check regularly if you:

• are over 30 and cannot remember your last reading
• have a parent or sibling with high blood pressure
• are carrying extra weight
• have diabetes or kidney disease
• had raised blood pressure during pregnancy
• smoke, or drink heavily

If you have been diagnosed with hypertension, most people are advised to check at least weekly, and more often after any change in dose. If you have never been checked, start now, there is no symptom that will prompt you later.

Blood pressure in pregnancy

Blood pressure in pregnancy is monitored closely for good reason. Raised pressure after 20 weeks, particularly alongside protein in the urine, can indicate pre-eclampsia, a condition that can become dangerous quickly for both mother and baby.

Warning signs that need urgent assessment include severe headache, visual disturbances such as flashing lights, pain below the ribs, sudden swelling of the face, hands or feet, and vomiting.

Do not manage raised blood pressure in pregnancy at a pharmacy counter. Antenatal care exists precisely to catch this, and it works. Attend your appointments even when you feel completely well.

Why readings differ between arms

It is normal for readings to differ slightly between your left and right arm. A small difference of a few points means nothing.

A consistent difference of more than about 10 to 15 points, however, is worth mentioning to a doctor, as it can indicate narrowing in one of the arteries. If you are being checked for the first time, having both arms measured is sensible; after that, use whichever arm read higher for ongoing monitoring.

Blood pressure and salt in Kenyan cooking

Reducing salt is the single most effective dietary change for blood pressure, and in most Kenyan households the salt is not mainly coming from the salt shaker.

The larger contributors are stock cubes and seasoning mixes, which are very high in sodium; processed and preserved meats; packet soups and instant noodles; and crisps and salted snacks.

Practical substitutions that do not sacrifice flavour: use more onion, garlic, ginger, dhania and chilli, cut stock cubes to half of what a recipe suggests, and taste before adding salt rather than adding it by habit. Palates adjust within a few weeks, and food stops tasting bland.

Get your blood pressure checked, free

At Chetu Chemist in Nyamasaria, Kisumu, blood pressure checks are free. No appointment, no purchase, no limit on how often you come. We will take the reading properly, write it down so you build a record, explain what it means, and tell you plainly if you need to see a doctor.

Walk in during opening hours, or call 0792 855 271.