A blood pressure of 108/66 mmHg is a good reading. It falls squarely in the “normal” category, which is defined as a systolic (top number) below 120 and a diastolic (bottom number) below 80. This reading is well above the threshold for low blood pressure, which starts at 90/60.
Where 108/66 Falls on the Chart
The American Heart Association classifies adult blood pressure into four categories:
- Normal: systolic below 120 and diastolic below 80
- Elevated: systolic 120 to 129 and diastolic below 80
- Hypertension Stage 1: systolic 130 to 139 or diastolic 80 to 89
- Hypertension Stage 2: systolic 140 or higher, or diastolic 90 or higher
At 108/66, both numbers sit comfortably in the normal range. You’re not close to elevated blood pressure, and you’re not close to the low blood pressure cutoff of 90/60 either. This is essentially a textbook healthy reading.
Why It Might Seem Low
If 108/66 feels like it’s on the lower side of normal, that’s because most people hear more about high blood pressure than low. But a reading in this range is typical for many healthy adults, particularly women and people who exercise regularly. In a study of nearly 3,700 young athletes, women averaged a systolic pressure of about 116, and those in endurance or artistic sports tended to have even lower numbers. A reading of 108 systolic fits right in with an active, healthy population.
Blood pressure also naturally varies throughout the day. It dips during sleep, rises in the morning, and fluctuates with activity, stress, caffeine, and hydration. A single reading of 108/66 is a snapshot, not a permanent label. If your next reading comes back at 115/72, that’s equally normal.
When Lower Blood Pressure Becomes a Problem
Low blood pressure is only a medical concern when it causes symptoms. The numbers alone don’t tell the whole story. Most healthcare professionals won’t flag a reading unless you’re experiencing issues like:
- Dizziness or lightheadedness, especially when standing up
- Blurred or fading vision
- Fatigue that doesn’t improve with rest
- Trouble concentrating
- Fainting
- Nausea
A sudden drop matters more than a consistently low number. A shift of just 20 mmHg in the top number, say from 110 down to 90, can cause dizziness or fainting even though 110 is perfectly normal on its own. This is why some people feel lightheaded when they stand up quickly. That specific pattern, called orthostatic hypotension, is diagnosed when systolic pressure drops by 20 mmHg or diastolic drops by 10 mmHg within a few minutes of standing.
If your blood pressure regularly reads around 108/66 and you feel fine, there’s nothing to address. Your heart is pumping efficiently, and your blood vessels aren’t under excess strain.
What This Means for Long-Term Health
A normal blood pressure reading like 108/66 is one of the strongest markers of cardiovascular health. High blood pressure is a leading risk factor for heart attack, stroke, and kidney disease, and those risks start climbing once systolic pressure passes 120. Being well below that threshold means your arteries are under less daily stress, which adds up over decades.
The goal for most adults isn’t to hit one specific number but to stay consistently in the normal range. If you’re already there, the best thing you can do is maintain whatever habits got you there: regular physical activity, a reasonable diet, limited alcohol, and adequate sleep. Blood pressure tends to rise with age, so a healthy baseline in your 20s or 30s gives you more room as you get older.