The formula
How to calculate mean arterial pressure
Mean arterial pressure is the average pressure driving blood through the circulation over a full cardiac cycle. It matters more than either individual reading for organ perfusion, which is why it is monitored in critical care.
Diastole is weighted twice as heavily as systole because at a normal heart rate the heart spends roughly two thirds of each cycle relaxed. At high heart rates that ratio shifts and the approximation becomes less exact.
What to enter:
- Systolic pressure (mmHg)
- Diastolic pressure (mmHg)
No submit button: type and the answer moves. Your inputs end up in the link, so the page can be shared already filled in.
Consistency in how the underlying measurements are taken matters more than precision to the last decimal — measuring at the same time of day, in the same state of rest or hydration, makes readings taken weeks apart genuinely comparable in a way that a single very precise reading on its own is not.
Why mean arterial pressure matters
This kind of calculation gets used both out of general interest and ahead of a specific conversation — with a trainer, a midwife or a GP — where having an actual number ready, rather than a description, makes that conversation more concrete and specific.
Because the calculation depends on a formula rather than a device, it is useful anywhere a scale, a tape measure or a stopwatch is available, without needing specialist equipment — which is also exactly why it should be treated as an estimate rather than a clinical measurement.
A single number like this is most useful placed in context rather than read in isolation. Reference ranges exist because bodies vary considerably and still count as healthy across a wide spread of values, so a result sitting outside a commonly quoted range is a prompt to look more closely rather than a verdict on its own. The same figure, tracked consistently over time, tends to say more than any single reading ever will.
A calculator like this one is frequently used to prepare a specific number for an upcoming appointment, so that a description like "I think it has changed" can be replaced with an actual figure and a date it was measured on. Clinicians and trainers generally find a concrete number, however approximate, more useful to work from than a general impression.
Worked example
Take the figures the calculator starts with:
- Systolic pressure: 120 mmHg
- Diastolic pressure: 80 mmHg
That gives:
- Mean arterial pressure: 93.33 mmHg
- Pulse pressure: 40 mmHg
- Margin above 60 mmHg: 33.33 mmHg
Those starting figures exist only to show the calculation working, not as a target or a reference value to compare yourself against — replace them with your own measurements in the calculator above and the same formula applies exactly as shown.
Reading the result
A MAP of 70–100 mmHg is generally considered normal. Below about 60 mmHg, perfusion of the brain and kidneys may be inadequate, which is the threshold used in sepsis and shock protocols.
Where this goes wrong. A single reading means little. Blood pressure varies with time of day, posture, caffeine and stress, and the cuff must be correctly sized. Any concern about your blood pressure should go to a clinician rather than a calculator.
As with any general-purpose formula, the result here is an estimate derived from population averages, not a measurement specific to you — a reasonable starting point for a conversation with a qualified professional, not a replacement for one. Nothing on this page is medical advice.
Between 70 and 100 mmHg for most adults. Clinical targets in intensive care usually aim to keep it above 65 mmHg to maintain organ perfusion.
Because the heart spends about twice as long in diastole as in systole at a resting heart rate, so the diastolic pressure applies for longer and is weighted accordingly.
It returns mean arterial pressure. With 120 mmHg systolic pressure and 80 mmHg diastolic pressure, that comes to 93.33 mmHg. Change any field and the figure moves with it.
It uses a published formula applied exactly as defined, so the arithmetic itself is precise — but the formula is a population-level estimate, and individual results can vary from it for reasons the formula has no way to account for. Treat the output as a reasonable estimate rather than a measured or diagnostic value.
For most people, yes — a single reading is a snapshot, while the same measurement repeated consistently over weeks or months shows a trend, which is generally more informative than any one figure taken in isolation.
Small differences between calculators usually come down to which published formula or reference dataset each one uses — several equations in this area exist in more than one accepted version. This page states the specific formula used in the section above, so it is possible to check directly whether another source is using the same one.