# What is my mean arterial pressure?

Estimates mean arterial pressure (MAP) from systolic and diastolic blood pressure as the diastolic pressure plus one third of the pulse pressure, or solves for any of the four from two.

- Page: https://www.acalculator.org/health/mean-arterial-pressure-calculator
- JSON spec: https://www.acalculator.org/health/mean-arterial-pressure-calculator.json
- Version: 079ef162ca6e

## Default answer

Example with the default inputs (Systolic (top number) 120 mmHg, Diastolic (bottom number) 80 mmHg): A blood pressure of 120 mmHg/80 mmHg gives a mean arterial pressure of 93.3 mmHg.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| sys | Systolic (top number) | The systolic blood pressure. |
| dia | Diastolic (bottom number) | The diastolic blood pressure. |
| map | Mean arterial pressure | The mean arterial pressure (MAP). |
| pp | Pulse pressure | Systolic minus diastolic pressure. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| sys | Systolic (top number) | The systolic blood pressure. |
| dia | Diastolic (bottom number) | The diastolic blood pressure. |
| map | Mean arterial pressure | MAP = diastolic + (systolic − diastolic) ÷ 3, to one decimal place. |
| pp | Pulse pressure | Systolic minus diastolic pressure. |

## Method

MAP = DBP + (SBP − DBP) ÷ 3; pulse pressure = SBP − DBP.

## Assumptions

- The formula weights the diastolic pressure two thirds and the systolic one third, because at a resting heart rate diastole lasts about two thirds of each heartbeat.
- At fast heart rates systole takes a larger share of each beat, and the formula underestimates the true mean pressure (Razminia 2004).
- This is an estimate from a cuff reading, for information only; it is not a measured arterial pressure and not medical advice.

## Worked examples

1. sys = 15,998.68649, dia = 10,665.790993 gives map = 12,443.422825, pp = 5,332.895497. Source: MAP = DBP + (SBP − DBP) ÷ 3 (Razminia 2004; Meaney 2000): 80 + 40 ÷ 3 = 93.3 mmHg.
2. sys = 18,665.134238, dia = 11,999.014867 gives map = 14,221.054658.
3. map = 8,665.955182, dia = 6,666.119371 gives sys = 12,665.626804.
4. map = 13,332.238742, pp = 5,999.507434 gives dia = 11,332.40293, sys = 17,331.910364.

## FAQ

### What is mean arterial pressure?

The average pressure in the arteries over one heartbeat. It is closer to the diastolic (bottom) number than to the systolic (top) number, because the heart spends about two thirds of each beat relaxing.

### How do I calculate MAP by hand?

Take the diastolic pressure and add one third of the pulse pressure (systolic minus diastolic). For 120/80: 80 + (120 − 80) ÷ 3 = 80 + 13.3 = 93.3 mmHg.

### What is pulse pressure?

The systolic pressure minus the diastolic pressure. For 120/80 it is 40 mmHg. It is the rise in pressure with each heartbeat.

### Why is the formula only an estimate?

The one-third weighting assumes diastole takes about two thirds of each beat, which fits resting heart rates. When the heart beats fast, systole takes a larger share, and the formula underestimates the true mean (Razminia and others, 2004). In hospital, MAP can be measured directly with an arterial line.

### Can I find the systolic pressure from the MAP?

Yes. Rearranged, SBP = 3 × MAP − 2 × DBP. With a MAP of 65 and a diastolic pressure of 50: 3 × 65 − 2 × 50 = 95 mmHg. The calculator solves for any value from any two others.

### Can I use kilopascals?

Yes. Pick kPa in the unit list. The calculator converts with 1 mmHg = 0.133322 kPa (the conventional millimetre of mercury, 13.5951 g/cm³ × 9.80665 m/s²).

## Sources

- Razminia M, Trivedi A, Molnar J, et al. Validation of a new formula for mean arterial pressure calculation: the new formula is superior to the standard formula. Catheter Cardiovasc Interv. 2004;63(4):419-425 (the standard formula weights systolic 1/3 and diastolic 2/3). https://doi.org/10.1002/ccd.20217
- Meaney E, Alva F, Moguel R, Meaney A, Alva J, Webel R. Formula and nomogram for the sphygmomanometric calculation of the mean arterial pressure. Heart. 2000;84(1):64 (Figure 1 compares the standard multiplier of the pulse pressure, 0.333, with 0.412, against an electronically measured MAP). https://doi.org/10.1136/heart.84.1.64
- National Institute of Standards and Technology. Guide for the Use of the International System of Units (SI), NIST Special Publication 811, Appendix B (millimeter of mercury, conventional = 133.3224 Pa). https://www.nist.gov/pml/special-publication-811