Pulse Pressure Calculator

How it is calculated

Enter the two numbers from a blood pressure reading in mmHg: systolic (the top number) and diastolic (the bottom number). The tool calculates pulse pressure = systolic − diastolic and the ratio systolic ÷ diastolic. The pulse pressure is shown as a whole number of mmHg and the ratio to two decimals. Both values must be greater than zero, and systolic cannot be lower than diastolic: if you swap them, the tool returns nothing instead of a negative number. Equal values are accepted and give 0 mmHg and a ratio of 1.00. The tool does not judge the figures or say whether a reading is normal; interpretation depends on age, health and repeated measurements, and belongs to a clinician.

Common mistakes

• Swapping the two numbers. Systolic is always the larger top number, and entering 82 first and 128 second returns no result.
• Entering the mean arterial pressure or the pulse rate (beats per minute) in place of one of the pressures. Pulse pressure is not the pulse rate.
• Basing a conclusion on one reading. Blood pressure varies through the day, so a single pair of numbers says little.
• Mixing units, for example kPa for one number and mmHg for the other. Both must be in mmHg.
• Reading the ratio as a second pressure. It is a dimensionless comparison with no unit.