How to read the two numbers
Systolic, the top number, is the pressure in your arteries while your heart beats. Diastolic, the bottom number, is the pressure between beats. Both matter: either one crossing its threshold puts the reading in the higher category. A reading of 142/78 counts as high on the systolic number alone.
The NHS ranges
| Category | Clinic reading | Home average |
|---|---|---|
| Low | below 90/60 | below 90/60 |
| Ideal | 90/60 to 120/80 | 90/60 to 120/80 |
| Slightly raised | 120/80 to 140/90 | 120/80 to 135/85 |
| High (stage 1) | 140/90 or above | 135/85 or above |
| Very high (stage 2) | 160/100 or above | 150/95 or above |
| Emergency range | 180/120 or above | 180/120 or above |
Home readings run lower than clinic ones. The white-coat effect is real and measured, which is why NICE sets home thresholds five points lower. If a clinic reading comes back high, your GP will usually confirm it with a week of home readings or a 24-hour monitor before diagnosing anything.
One reading proves almost nothing
Blood pressure moves constantly. Caffeine, a stressful phone call, a full bladder, or simply talking during the measurement can add ten points. The NHS diagnoses high blood pressure on repeated readings over days or weeks, never on one number.
To measure properly: sit quietly for five minutes first, back supported, feet flat, arm resting at heart height. No caffeine or exercise in the previous half hour. Take two readings a minute apart and record the second. Same time each day, ideally morning and evening for a week.
Why the trend beats the snapshot
A single 138/88 tells you little. Ten readings drifting from 128/82 to 138/88 across a year tell you a great deal, and they tell your GP even more. Rising pressure is one of the five markers of metabolic syndrome, and it rarely travels alone: waist size, triglycerides, and blood glucose tend to move with it.
BioMetRx keeps every reading in one place alongside your weight, glucose, activity, and lab results, so the trend is visible the moment it starts, not the year after. See how it works.
Frequently asked questions
Is 140/90 high blood pressure?
At a clinic, 140/90 is the threshold for stage 1 high blood pressure. Measured at home, the threshold is lower: 135/85. Either way, one reading is not a diagnosis; your GP will confirm with repeated measurements.
What is a normal blood pressure by age?
The NHS uses the same adult thresholds at every age; there is no separate "normal for 60". Pressure does tend to rise with age, but the risk it carries rises too, which is why the target stays put.
Why is my home reading lower than at the GP?
Clinic environments raise most people's blood pressure — the white-coat effect. It is common enough that NICE sets home diagnostic thresholds five points below clinic ones.
When is blood pressure an emergency?
At 180/120 or above, rest for five minutes and re-measure. If it stays that high, contact your GP the same day or call 111. With chest pain, shortness of breath, sudden vision changes, or a severe headache, call 999.
How often should I check my blood pressure?
With an ideal reading, once a year is fine. If it is drifting up, or your GP has asked you to monitor, a week of morning and evening readings gives a far truer picture than occasional spot checks.
This page uses NHS and NICE adult thresholds. It is educational, not a diagnosis. See our medical disclaimer.