Total Peripheral Resistance

Human Physiology • Cardiovascular Physiology

Written by STEM Calculators Team Published April 13, 2026 Updated April 13, 2026

Total peripheral resistance calculator

Estimate total peripheral resistance from mean arterial pressure, right atrial pressure, and cardiac output, compare two conditions, and optionally normalize resistance to body size.

Resistance output mode

Quick comparison preset

Compare two conditions

Include normalized resistance mode using body surface area

Teaching interpretation bands for total peripheral resistance are approximate: reduced < 12 Wood units, typical 12–20 Wood units, elevated > 20 Wood units.

State A

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Preset

Pressures are entered in mmHg and cardiac output in L/min.

Mean arterial pressure (MAP)

Right atrial pressure / CVP

Cardiac output (CO)

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Optional columns: label,map,rap,co,bsa,preset. Use one or two rows. If BSA is supplied, the calculator can also show indexed resistance when normalization is enabled.

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Total peripheral resistance and systemic vascular tone

A total peripheral resistance calculator estimates the net resistance offered by the systemic circulation to blood flow. The main computed quantity is total peripheral resistance, and it is determined from mean arterial pressure, right atrial pressure, and cardiac output.

Total peripheral resistance reflects how strongly the systemic vasculature opposes flow. It rises with vasoconstriction, falls with vasodilation, and helps explain how arterial pressure and cardiac output are linked across the systemic circuit.

Core definitions and formulas

The effective pressure driving blood through the systemic circulation is the difference between mean arterial pressure and right atrial pressure. Total peripheral resistance is that driving pressure divided by cardiac output.

\[ \begin{aligned} \Delta P &= MAP - RAP \end{aligned} \] \[ \begin{aligned} TPR &= \frac{MAP - RAP}{CO} \end{aligned} \] \[ \begin{aligned} TPR_{\text{dyn}\cdot \text{s}\cdot \text{cm}^{-5}} &= TPR_{\text{Wood}} \cdot 80 \end{aligned} \]

Here, \(MAP\) is mean arterial pressure, \(RAP\) is right atrial pressure or central venous pressure, \(CO\) is cardiac output, and \(TPR\) is usually first reported in Wood units \((\text{mmHg}\cdot \text{min}/\text{L})\). A larger driving pressure increases resistance only if cardiac output does not rise proportionally, while a larger cardiac output lowers the calculated resistance if the pressure gradient stays similar.

How to interpret results

A higher total peripheral resistance usually suggests stronger systemic vasoconstriction or increased vascular tone. A lower value often suggests vasodilation or reduced systemic resistance, as may occur in shock-like distributive states. In normalized mode, indexed resistance adjusts the result using body surface area, which can help compare people of different sizes.

The driving pressure is especially important because it shows that systemic resistance depends on the pressure drop from arteries to the right atrium, not on arterial pressure alone. Comparison mode is useful for showing how vasoconstriction, vasodilation, or altered cardiac output shifts the balance.

Common pitfalls

Using MAP alone instead of subtracting RAP or CVP.
Mixing Wood units with dyn·s·cm^-5 without converting.
Ignoring the effect of cardiac output on the final resistance value.
Interpreting a high resistance value without checking whether flow is reduced.

Micro example: if \(MAP = 93\) mmHg, \(RAP = 3\) mmHg, and \(CO = 5.0\) L/min, then \(\Delta P = 90\) mmHg and \(TPR = 90/5.0 = 18.0\) Wood units. In dyn·s·cm^-5, that is \(18.0 \cdot 80 = 1440\).

This tool is useful for hemodynamics, vascular physiology, and systemic circulation comparisons. It is not a full clinical model; the next step for deeper interpretation is often cardiac output, mean arterial pressure, venous return, or blood flow–pressure–resistance analysis.

Frequently Asked Questions

What does a total peripheral resistance calculator measure?

It estimates the net resistance of the systemic vasculature to blood flow. The result depends on the pressure drop across the systemic circulation and the cardiac output passing through it.

How is total peripheral resistance calculated?

Total peripheral resistance is calculated with the formula TPR = (MAP - RAP) / CO. For example, if MAP is 93 mmHg, RAP is 3 mmHg, and cardiac output is 5.0 L/min, TPR is 18.0 Wood units.

Why do mean arterial pressure and right atrial pressure both matter?

Blood flow through the systemic circulation depends on the pressure difference from arteries to the right atrium. That is why the driving pressure is MAP minus RAP, not MAP alone.

What is the difference between Wood units and dyn·s·cm^-5?

They are two ways of expressing vascular resistance. To convert Wood units to dyn·s·cm^-5, multiply by 80.

When is indexed resistance useful in a total peripheral resistance calculator?

Indexed resistance is useful when body size should be taken into account. It uses body surface area to normalize the result, which can help compare different individuals more fairly.

Total Peripheral Resistance

State A

State B

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Calculation steps

Vascular resistance gauge

Systemic circuit schematic

Comparison bar chart

MAP–CO–TPR triangle diagram

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Frequently Asked Questions

State A

State B

Paste or import CSV data

Calculation steps

Vascular resistance gauge

Systemic circuit schematic

Comparison bar chart

MAP–CO–TPR triangle diagram

Rate this calculator

Frequently Asked Questions

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