Blood Pressure 128 over 31 - what do these values mean?
No. 128/31 counts as normal by its upper number, but the lower number of 31 is very low (diastolic below 40). Measure again now. If the reading is real and you feel faint, confused, short of breath, or cold and clammy, call 911 (US) or your local emergency number. Otherwise contact a doctor today.
- International (ESH)Normal
- US guideline (AHA/ACC)Elevated
- Pulse pressure97 mmHg
- Mean arterial pressure63 mmHg
What to do now
- Measure again now, after a few minutes of quiet rest.
- If the reading is real and you feel faint, confused, short of breath, or cold and clammy: call 911 (US) or your local emergency number.
- No symptoms but the reading is confirmed? Contact a doctor today.
- Small changes keep it from rising: less salt, more vegetables and fruit, daily activity.
- Re-check at least once a year.
The systolic (upper) number decides the category: when the two numbers fall into different categories, the higher one counts. Your lower number of 31 is very low (diastolic below 40), and the gap of 97 mmHg between the two numbers is wide — see “What to do now” above.
Blood pressure 128/31 on the blood pressure chart
- Low blood pressure
- Ideal (optimal)
- Normal
- High normal
- Hypertension stage 1
- Hypertension stage 2
- Hypertension stage 3
Read more about this category: Normal.
International and US categories
| Category | Systolic / diastolic (mmHg) | US (AHA/ACC) |
|---|---|---|
| Ideal (optimal) | < 120 and < 80 | Normal |
| Normal | 120–129 and/or 80–84 | Elevated / stage 1 |
| High normal | 130–139 and/or 85–89 | Stage 1 |
| Hypertension stage 1 | 140–159 and/or 90–99 | Stage 2 |
| Hypertension stage 2 | 160–179 and/or 100–109 | Stage 2 |
| Hypertension stage 3 | ≥ 180 and/or ≥ 110 | Stage 2 / severe > 180/120 |
| Low blood pressure | systolic < 90 or diastolic < 60, the other number not raised | Low |
International categories: European Society of Hypertension (ESH) 2023, office readings. Home readings use lower thresholds — hypertension from an average of 135/85. A reading with one raised and one low number counts by the raised one.
Pulse pressure and mean arterial pressure
A pulse pressure of 97 mmHg is wide (above 60). In older adults it usually reflects stiffer arteries. Mean arterial pressure — the average pressure perfusing your organs — is about 63 mmHg. That is low: below about 65, organs such as the brain and kidneys can be under-supplied. If you feel faint, confused, short of breath, or cold and clammy, act on it now.
Measure it right
- No caffeine, exercise or smoking for 30 minutes; empty your bladder.
- Sit with back supported, feet flat, for 5 minutes. Don't talk.
- Upper-arm cuff of the right size on bare skin, arm supported at heart level.
- Two readings a minute apart, morning and evening, for 7 days — use the average.
Details: Measuring Blood Pressure Correctly: Step by Step
Check another reading
Nearby readings
Sources: ESH 2023 guideline (international categories) · AHA/ACC 2025 guideline (US categories, unchanged from 2017) · MedlinePlus: Low blood pressure. Reviewed by the BloodPressureOK editorial team · last reviewed October 25, 2026.
This page explains one reading in general terms. High blood pressure is diagnosed from repeated measurements. Not medical advice — talk to your doctor about your readings.