What this calculator does
Shock index works out heart rate divided by systolic blood pressure, a quick marker of circulatory stress. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
FormulaShock index = heart rate / systolic blood pressure
The inputs explained
| Field | What to enter |
|---|---|
| Heart rate (bpm) | A number, measured in bpm. Starts at 80. |
| Systolic blood pressure (mmHg) | A number, measured in mmHg. Starts at 120. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with heart rate
Every other input is held at the calculator’s starting values while heart rate varies. Select any row to load that scenario into the calculator.
How the answer changes with heart rate
| Heart rate (bpm) | Shock index | Typical resting range | Reading |
|---|---|---|---|
| 40 | 0.33 | 0.5 - 0.7 | Within the typical resting range |
| 60 | 0.50 | 0.5 - 0.7 | Within the typical resting range |
| 80 | 0.67 | 0.5 - 0.7 | Within the typical resting range |
| 120 | 1.00 | 0.5 - 0.7 | Elevated: seek medical attention if this is a real reading |
| 160 | 1.33 | 0.5 - 0.7 | Elevated: seek medical attention if this is a real reading |
| 240 | 2.00 | 0.5 - 0.7 | Elevated: seek medical attention if this is a real reading |