Diastolic-to-Systolic Ratio Calculator

About this calculator

The diastolic-to-systolic ratio (DBP/SBP) divides your lower blood pressure reading by your upper one, alongside two related figures: pulse pressure, calculated as systolic minus diastolic, and mean arterial pressure (MAP), approximated as diastolic plus one-third of pulse pressure. A ratio in the healthy range generally sits around 0.6 to 0.7; a ratio that drifts noticeably lower usually reflects a widening pulse pressure, which happens as large arteries stiffen with age.

Cardiologists and researchers reference pulse pressure and the DBP/SBP ratio, rather than either number alone, because a wide pulse pressure is an independent marker of arterial stiffness and has been linked in epidemiological studies to elevated cardiovascular risk, even when both individual readings look unremarkable. MAP itself is the figure clinicians actually track during critical care and anesthesia, since it represents average perfusion pressure to organs across a full cardiac cycle, not just the peak and trough.

This calculator takes your systolic and diastolic readings and returns the DBP/SBP ratio, pulse pressure, and mean arterial pressure in one step.