Home blood pressure numbers, explained
What the two numbers mean, why home readings use a different target, and what to do if a reading is very high.
High blood pressure rarely has symptoms, which is why so many people don't know they have it. The World Health Organization estimates that 41% of women with high blood pressure are unaware of it, because they were never diagnosed. Measuring at home is one of the simplest ways to find out where you stand.
The two numbers
A reading like 128/82 has two parts:
- Systolic (the top number) is the pressure when your heart beats.
- Diastolic (the bottom number) is the pressure between beats.
Both are measured in millimetres of mercury (mmHg).
Why the home target is lower
Readings taken at a clinic tend to be higher than readings taken calmly at home. So guidance for home readings uses a lower threshold. In the UK, NICE guideline NG136 uses an average home reading of 135/85 or more as the point where high blood pressure is diagnosed, and 150/95 or more for the next stage.
That's the guide femLove uses for its labels:
| Average home reading | What femLove shows |
|---|---|
| Below 135/85 | In target |
| 135/85 or more | Raised |
| 150/95 or more | High |
| 180/120 or more | Very high |
Your own doctor may set a different target for you, especially if you're pregnant, have diabetes, or take blood pressure medication. Their advice comes first.
Getting a fair reading
- Sit quietly for five minutes first, back supported, feet flat on the floor.
- Rest your arm on a table so the cuff is at heart height.
- Avoid caffeine, exercise and smoking for 30 minutes before.
- Take two readings a minute apart, morning and evening, for several days. One reading on its own says very little.
- Use the same arm each time, and note it.
If a reading is very high
If you get a reading of 180/120 or more, sit quietly for five minutes and measure again.
- If you also have chest pain, shortness of breath, back pain, numbness or weakness, a change in your vision, or difficulty speaking, call 112 or your local emergency number straight away.
- If you feel well but it's still that high, contact your GP or out-of-hours service the same day.
This article is general information, not medical advice. If you're worried about your blood pressure, speak to a doctor or pharmacist.
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