Last updated: May 18, 2026

If you've ever had your blood pressure checked on both arms and noticed different numbers, you're not imagining things. Blood pressure readings can vary between your left and right arms.

This comes down to the way arteries branch off from the heart and how blood flows through each side of your body. That’s why it is important to understand which arm to use when tracking blood pressure.

For the most accurate results, medical guidelines recommend measuring blood pressure in both arms initially, then continuing to use the arm with the higher reading for ongoing monitoring.

What is blood pressure?

Blood pressure is the force of blood against the walls of your blood vessel.

A normal reading is around 120/80 mmHg. High blood pressure, or hypertension, is diagnosed when readings are consistently 130/80 mmHg or higher over time. Because blood pressure can change due to stress, activity, or other factors, multiple readings are needed for an accurate diagnosis.

Why might your blood pressure be different between your two arms?

Blood pressure can differ between arms due to natural differences in blood vessel structure, blood flow, or underlying health conditions. These differences are usually small and harmless, but in some cases, they may indicate changes in the arteries that affect circulation.

In many people, the arteries supplying each arm branch slightly differently from the aorta, which can lead to small variations in blood pressure readings.

Other factors, such as temporary muscle tension or body position, can also affect blood flow and cause minor differences between arms.

How should you have your blood pressure checked?  

To check your blood pressure accurately:

• Measure it in both arms simultaneously the first time.

• A difference of less than 5 mmHg between the left and right arm is normal.

• A difference 5-10 mmHg may need monitoring.

• A difference greater than 10 mmHg should be evaluated by a healthcare provider.

• Use the arm with the higher reading for future checks

Blood vessels can narrow over time due to cholesterol deposits, which can increase the resistance to blood flow. As a result, blood pressure increases. Think of this as similar to the way that mineral deposits on the inner surface of a hose can reduce water flow.

Nutrition patterns that support heart health can matter here too, especially when they help reduce inflammation and support healthier blood vessels.

In rare cases, a significant and persistent difference in blood pressure between the left and right arm can also be a sign of aortic dissection, which requires immediate medical attention.

What is peripheral artery disease?

One possible cause of blood pressure differences between arms is peripheral artery disease (PAD), a condition where arteries narrow and reduce blood flow.

Key facts:

• The risk of PAD increases with age.

• Over half of affected people with PAD do not have symptoms.

• Smokers have a 2.5 times higher risk of developing PAD.  

Because PAD can develop without clear symptoms, monitoring your blood pressure in both arms can help detect potential issues early.

The research behind these recommendations

Research shows that even small differences in blood pressure between arms may be linked to a higher risk of cardiovascular disease.

For example, differences greater than 5 mmHg have been associated with increased mortality risk over time. Blood pressure differences are also more common in people with conditions such as hypertension and diabetes.

Because of this, checking blood pressure in both arms can provide important insight into cardiovascular health and help identify higher-risk individuals early.

Which arm should I use to take my blood pressure?  

After checking both arms, the arm with the higher reading is typically used for future measurements. This gives the most accurate picture of your cardiovascular risk.

Periodic rechecking may help confirm consistency. Of course, if you have an arm injury or other serious reason to avoid checking your blood pressure in one of your arms, then you should check your blood pressure in the uninjured arm.  

Tips for Accurate Blood Pressure Measurement

Getting accurate blood pressure readings depends on how and when you measure it.

Measure Your Blood Pressure More Than Once

A single reading may not reflect your actual blood pressure. Since it can change from minute to minute, it is better to take multiple readings and average them to get a more accurate result.

Pay Attention to Factors That Affect Readings

Several everyday factors can influence your results. Blood pressure is affected by stress, body position, hydration, hormone levels, salt intake, and medications. Being consistent with how and when you measure your blood pressure can help reduce these variations.

Track Your Readings Over Time

Looking at trends over time gives a clearer picture than a single measurement. Regularly checking your blood pressure at home can help you notice changes early and monitor your overall cardiovascular health.

Use Tools to Support Tracking

If you already track your health data with a wearable, it can help you spot patterns alongside your home readings and provide a more complete picture of your health.

Conclusion

Knowing which arm to take blood pressure from is more than a small detail. Your left and right arms can give different blood pressure readings, which is why checking both sides at least once is a smart starting point. If one arm consistently reads higher, stick with that one going forward. It gives a more accurate picture of what your heart and arteries are actually doing.

Tracking your numbers over time matters too. Patterns tell you more than any single reading ever will, and noticing a change between arms early can give you and your doctor a real head start.