Blood Pressure Calculator

What the two readings tell you

Enter systolic pressure (the upper number, measured as the heart beats) and diastolic pressure (the lower number, measured between beats) in mmHg. The result shows a pulse pressure, an estimated mean arterial pressure (MAP), and—only in adult mode—an adult reference category. These values are calculated from the reading you enter; they are not measurements of blood flow or a diagnosis.

For example, a reading of 118/76 mmHg gives a pulse pressure of 42 mmHg and an estimated MAP of 90 mmHg after rounding to a whole number. MAP is an approximation commonly used for a normal heart rate, not a direct measurement of the pressure waveform.

How the adult reference is assigned

Adult mode compares both numbers with the US adult categories published by the American Heart Association. The higher applicable category takes precedence: normal is below 120 systolic and below 80 diastolic; elevated is 120–129 with diastolic below 80; stage 1 is 130–139 systolic or 80–89 diastolic; and stage 2 is 140 or higher systolic or 90 or higher diastolic. The tool also labels a reading low when systolic is below 90 or diastolic is below 60. Its severe-reading label is triggered when either number is greater than 180 systolic or greater than 120 diastolic. The AHA distinguishes a severe reading from an emergency based on symptoms; the calculator cannot make that distinction. The category is a quick reference for adults in a US context, not confirmation of hypertension.

For children, the mode reports only the numeric pulse pressure and estimated MAP. It does not calculate an age, sex, height, or percentile-based category.

Enter and read a paired measurement

1. Choose the appropriate mode

   Use adult mode for an adult reading. Child mode is limited to arithmetic and does not apply pediatric reference percentiles.

2. Copy the numbers in the right order

   Enter the upper systolic number first and the lower diastolic number second, both in mmHg. The result appears when both are numeric, the diastolic value is above zero, and systolic is greater than diastolic.

3. Review each output separately

   Read the adult category as a reference label, then note pulse pressure and estimated MAP. Each calculated output is rounded to a whole mmHg; retain the original monitor reading when keeping a record.

Questions about the calculated result

Limits of a single-reading calculation

This calculator provides arithmetic and a reference category only. It cannot diagnose a condition, assess symptoms, or guide medication decisions.

• Adult categories are the US AHA reference shown by this tool; other jurisdictions and clinical circumstances may use different protocols. A health professional confirms a diagnosis using appropriate measurements and context.
• The severe-reading label is a numeric trigger, not an emergency assessment. The AHA advises urgent action when a reading above 180 systolic and/or 120 diastolic is accompanied by concerning symptoms such as chest pain, shortness of breath, weakness, vision changes, or difficulty speaking. Seek emergency help for such symptoms; the calculator cannot assess them.
• A low label is also not a diagnosis. The AHA describes below 90/60 mmHg as a common low-reading reference, but symptoms and personal circumstances affect its meaning.
• Estimated MAP is a simplified approximation and may not represent an individual’s directly measured mean pressure. Pediatric mode provides no validated pediatric classification.