The top number, peak pressure during ventricular contraction.
The bottom number, the resting pressure between beats.
The equation, and where it comes from
MAP = (SBP + 2 x DBP) / 3
The 2:1 diastolic weighting reflects that roughly two thirds of a cardiac cycle at a normal heart rate is spent in diastole. The form shown is algebraically identical to DBP + (SBP - DBP) / 3.
How to read the result
A MAP of 70 mmHg is the figure most often quoted as the lower bound for perfusing the major organs; 70 to 100 mmHg is the usual normal range.
Your patient's numbers never leave this device
The map (mean arterial pressure) arithmetic runs in JavaScript inside your own browser. There is no server call when you type, nothing is written to a database, nothing is logged, and no account is involved. Once the page has loaded you can disconnect from the network and it still works.
That matters more here than on an ordinary calculator. Values entered on a hospital workstation come off a real chart, and this tool deliberately does not remember them: close the tab and they are gone, including for the next person who uses that machine.
Frequently asked questions
- What is the formula for MAP?
- MAP = (systolic + 2 x diastolic) / 3. The diastolic figure is doubled because the heart spends about twice as long in diastole as in systole at a normal rate, so diastolic pressure contributes more to the average. Writing it as diastolic + (systolic - diastolic) / 3 gives exactly the same number.
- Why does MAP matter more than systolic pressure?
- Organ perfusion depends on the average pressure over the whole cardiac cycle rather than the peak. A patient can have a reassuring systolic number and a MAP that is too low to perfuse the kidneys or brain, which is why critical care targets are usually written as a MAP rather than a systolic.
- What is a normal MAP?
- Roughly 70 to 100 mmHg in an adult. Below about 70 mmHg is where perfusion of the major organs starts to be a concern, and this calculator labels the result against that range. The label is a reference range, not an assessment of a particular patient.
- How is MAP different from pulse pressure?
- Pulse pressure is systolic minus diastolic, the size of the swing. MAP is the time-weighted average of the whole cycle. They answer different questions, so this calculator shows both: a wide pulse pressure with a normal MAP means something quite different from a narrow one.
- Does this calculator send my numbers anywhere?
- No. The arithmetic runs in JavaScript in your own browser. There is no server call when you press calculate, nothing is logged, and the page works with your network disconnected once it has loaded.