Mean arterial pressure calculator (MAP from systolic and diastolic BP)
For healthcare professionals and students. Check results against your local protocols and clinical judgement; this tool does not give medical advice.
This mean arterial pressure calculator estimates MAP from a cuff blood pressure. Type the systolic and diastolic pressures in mmHg or kPa and it shows the MAP from the standard bedside formula, the pulse pressure, the MAP in both units and two published alternatives: Meaney’s 0.412 multiplier and the heart-rate-corrected formula of Razminia and colleagues. A small bar shows where the diastolic, mean and systolic values sit against the 65 mmHg reference line.
MAP is the average pressure driving blood through the organs over one cardiac cycle. Monitors and arterial lines measure it directly by integrating the pressure waveform; when only a cuff reading is available, the formulas below give an estimate that students are expected to calculate by hand and clinicians use to check a number quickly.
How to use the Mean Arterial Pressure Calculator
- Choose the unit, mmHg or kPa.
- Enter the systolic and diastolic pressures from the same reading.
- Optionally add the heart rate to see the heart-rate-corrected MAP.
- Read the MAP, pulse pressure and the alternative estimates; open the working rows to see each formula with your numbers.
- Use Copy result to paste the values into notes; the copied text includes the professional-use notice.
Mean Arterial Pressure Calculator features
Standard formula
MAP = DBP + ⅓(SBP − DBP), the same as (SBP + 2 × DBP) ÷ 3, rounded for display and exact in the working.
mmHg and kPa
Enter either unit; conversions use 1 mmHg = 0.133322 kPa.
Two published alternatives
Meaney et al. (0.412 × pulse pressure) and Razminia et al. (heart-rate-corrected) side by side.
Visual check
A bar shows the diastolic–systolic range, the MAP marker and the 65 mmHg line.
Sanity warnings
Flags inverted values, readings that look like the wrong unit, very narrow or wide pulse pressures and MAP below 65 mmHg.
Mean arterial pressure formula
At a resting heart rate the heart spends roughly one third of each cycle in systole and two thirds in diastole, so the time-weighted average pressure sits about a third of the way from diastolic to systolic: MAP ≈ DBP + (SBP − DBP) ÷ 3. The difference SBP − DBP is the pulse pressure. For 120/80 mmHg the pulse pressure is 40 mmHg and the MAP is 80 + 40 ÷ 3 = 93.3 mmHg (12.4 kPa).
Because the fraction of the cycle spent in systole changes with heart rate and arterial stiffness, researchers have proposed other multipliers. Meaney E, Alva F, Moguel R, et al. Heart 2000;84(1):64 compared cuff formulas with damped catheter pressures in 150 patients and proposed MAP = DBP + 0.412 × PP. Razminia M, Trivedi A, Molnar J, et al. Catheter Cardiovasc Interv 2004;63(4):419–425 paced 12 patients at increasing heart rates and validated MAP = DBP + [0.33 + (HR × 0.0012)] × PP. For 120/80 mmHg these give 96.5 mmHg and, at 60 bpm, 96.1 mmHg.
Worked values at a glance
| Blood pressure | Pulse pressure | MAP (⅓ rule) | MAP (Meaney 0.412) |
|---|---|---|---|
| 90/50 mmHg | 40 | 63.3 | 66.5 |
| 100/60 mmHg | 40 | 73.3 | 76.5 |
| 120/80 mmHg | 40 | 93.3 | 96.5 |
| 140/90 mmHg | 50 | 106.7 | 110.6 |
| 160/100 mmHg | 60 | 120.0 | 124.7 |
Why 65 mmHg appears on the chart
The Surviving Sepsis Campaign international guidelines (Evans L, Rhodes A, Alhazzani W, et al. Crit Care Med 2021;49(11):e1063–e1143) recommend an initial MAP target of 65 mmHg over higher targets for adults with septic shock who need vasopressors. The line is a reference point for that specific situation, not a normal range: appropriate targets depend on the patient and the condition, and later guideline editions should be checked. A formula estimate from a cuff is not a substitute for a measured MAP when decisions depend on a few mmHg.
Mean Arterial Pressure Calculator FAQ
How do you calculate mean arterial pressure?
Add one third of the pulse pressure to the diastolic pressure: MAP = DBP + (SBP − DBP) ÷ 3. For 120/80 mmHg the mean arterial pressure is 80 + 13.3 = 93.3 mmHg. The mean arterial pressure calculator above does this for any reading in mmHg or kPa.
Is MAP the same as (SBP + 2 × DBP) ÷ 3?
Yes. Expanding DBP + (SBP − DBP) ÷ 3 gives (SBP + 2 × DBP) ÷ 3, so both forms give the same answer.
What is pulse pressure?
Pulse pressure is systolic minus diastolic pressure — 40 mmHg for a reading of 120/80. The calculator shows it alongside the MAP and warns when it is very narrow or very wide, because the one-third rule is least reliable at the extremes.
Why does my monitor show a different MAP?
Automated cuffs and arterial lines measure the mean pressure from the waveform rather than estimating it from two numbers, so a measured MAP can differ by a few mmHg from any formula. Use the measured value where it is available.
Which formula should I use?
The one-third rule is the standard taught and used at the bedside. The 0.412 and heart-rate-corrected versions are published alternatives shown for comparison; follow your local guidance on which to document.
How do I convert MAP from mmHg to kPa?
Multiply by 0.133322: 93.3 mmHg is 12.4 kPa. Choose kPa as the unit to enter readings in kilopascals directly; for other pressure units there is a general pressure converter.