Mean Arterial Pressure (MAP) Calculator
Calculate mean arterial pressure (MAP) from systolic and diastolic blood pressure with the standard MAP = DBP + (SBP − DBP)/3 formula.
How to use this tool
- Enter your systolic (top) blood-pressure number.
- Enter your diastolic (bottom) blood-pressure number.
- Read your estimated mean arterial pressure in mmHg.
- Compare the result with the reference table below.
The mean arterial pressure (MAP) calculator turns a standard blood-pressure reading into the average pressure that perfuses your organs, using the widely-taught MAP = DBP + (SBP − DBP)/3 formula.
Formula
MAP = DBP + (SBP − DBP) ÷ 3
Equivalently, MAP = (SBP + 2 × DBP) ÷ 3. The diastolic value is weighted twice because, at normal heart rates, roughly two-thirds of the cardiac cycle is spent in diastole.
How it works
Mean arterial pressure is the time-weighted average pressure in the large arteries over one cardiac cycle, and it is the pressure that actually drives blood flow (perfusion) to the organs. The bedside estimate MAP = DBP + (SBP − DBP)/3 weights diastole twice because the heart spends about two-thirds of each beat relaxing rather than contracting.
This one-third/two-thirds approximation is most accurate at resting heart rates. At fast heart rates the diastolic fraction shrinks, so a true MAP from an arterial line can differ from this estimate. A MAP near or above 60 mmHg is commonly cited as the minimum needed to perfuse the brain and kidneys, but the right target is patient-specific.
This calculator is provided for general information and education only and is not medical advice. Clinical formulas are screening and estimation tools, not diagnoses, and they assume valid, correctly-measured inputs. Always consult a qualified clinician before making any decision about your health.
Worked example
Blood pressure 120/80 mmHg
- Pulse pressure = SBP − DBP = 120 − 80 = 40 mmHg
- Divide by 3: 40 ÷ 3 = 13.3333 mmHg
- Add diastolic: 80 + 13.3333 = 93.3333 mmHg
- Round to two decimals = 93.33 mmHg
Mean Arterial Pressure = 93.33 mmHg (Typical range)
MAP for common blood-pressure readings
| Blood pressure (SBP/DBP) | MAP (mmHg) |
|---|---|
| 90/60 | 70.00 |
| 110/70 | 83.33 |
| 120/80 | 93.33 |
| 140/90 | 106.67 |
| 160/100 | 120.00 |
Key terms
- Mean Arterial Pressure (MAP)
- The average arterial pressure across one heartbeat; the effective driving pressure for blood flow to the organs.
- Systolic pressure (SBP)
- The peak arterial pressure as the heart contracts and ejects blood.
- Diastolic pressure (DBP)
- The lowest arterial pressure, occurring while the heart relaxes and fills between beats.
- Pulse pressure
- The difference between systolic and diastolic pressure (SBP − DBP).
Frequently asked questions
- What is a normal mean arterial pressure?
- For most adults MAP sits roughly between 70 and 100 mmHg. A MAP around or above 60 mmHg is often described as the minimum needed for adequate organ perfusion, but individual targets vary.
- Why is diastolic pressure weighted twice in the formula?
- At resting heart rates the heart spends about two-thirds of each cycle in diastole, so the average pressure is closer to the diastolic value, which the (SBP − DBP)/3 term captures.
- Is this MAP the same as an arterial-line MAP?
- It is a close estimate at normal heart rates. A true arterial-line MAP integrates the whole pressure waveform and can differ, especially when the heart rate is fast.