Perfusion Unit Converter

Convert flow, pressure, and cannula size units used in CPB, ECMO, and vascular access workflows.

Calculator

Unit converter

A compact perfusion unit converter with flow converter, pressure converter, and French size, gauge, and CPB tubing inch conversion references.

Inputs

Flow (L/min) Weight (kg)

Outputs

mL/min

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mL/kg/min

Weight required

Formula: mL/min = L/min × 1000

Formula: mL/kg/min = (L/min × 1000) / weight(kg)

Cannula / Catheter Size

Convert French size, approximate Gauge size, and outer diameter in millimeters for catheter and cannula size reference.

Size type French size (Fr)

Outputs

Outer diameter

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French equivalent

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Approximate Gauge reference

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Select a size type and enter a value to convert.

French size represents catheter or cannula outer diameter: 1 Fr = 1/3 mm. Gauge values are approximate references and may vary by device type, wall thickness, material, and manufacturer. For cannula selection, always check the manufacturer’s specification.

Cannula & Tubing Size Converter

Convert French size, diameter, gauge, and common CPB tubing inch sizes.

Diameter (cm)

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Diameter (mm)

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Fr-equivalent

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Fr-equivalent values are calculated from diameter only. They should not be used as a direct substitute for manufacturer cannula or tubing specifications. Actual flow performance depends on internal diameter, wall thickness, length, connector geometry, pressure drop, blood viscosity, and cannula design.

Pressure Drop Reference ▾

Pressure drop is manufacturer- and model-specific. It cannot be estimated from Fr size alone.

Manufacturer Cannula category Product family Model Size

Target flow

Reference source

Select a cannula to view pressure-drop reference data.

Note

Pressure-drop data is not available for this model yet. Pressure drop cannot be estimated from Fr size alone.

Available curve datasets▾

Only manufacturer/model/size combinations with digitized curve data can display a pressure-drop estimate.

Manufacturer pressure-flow curves are usually bench data and may not reflect actual clinical performance with blood. Actual flow performance depends on blood viscosity, Hct, temperature, cannula position, kinking, vessel size, circuit configuration, and patient condition.

▶ Methodology

Unit converter scope

This tool provides quick bedside conversions for perfusion flow, pressure, and cannula/catheter size reference.
Calculations are performed locally in the browser from the entered value and selected unit.
Results are calculation aids and should be interpreted with institutional practice and device specifications.

Flow conversions

Flow is entered in L/min.
mL/min = L/min × 1000
mL/kg/min = (L/min × 1000) / weight(kg), when weight is provided.

Pressure conversions

Pressure values are normalized internally using standard relationships between mmHg, kPa, cmH₂O, psi, and bar.
Blank or invalid inputs clear the calculated outputs.
Unit labels preserve standard clinical casing, such as mmHg, kPa, cmH₂O, and mL/min.

Cannula / catheter size conversions

French size uses the standard outer-diameter relationship: diameter(mm) = Fr ÷ 3.
Gauge to mm and Gauge to French values are lookup-based approximate references, not exact formula conversions.
Actual inner and outer diameters may vary by device type, material, wall thickness, and manufacturer.

Unit Converter FAQ

What is the relationship between French size and millimeters?

French size is based on outer diameter. To convert Fr to mm, divide by 3.

Can Gauge be converted exactly to French size?

No. Gauge values are approximate references because dimensions vary by catheter design, wall thickness, and manufacturer.

Is this converter for ECMO cannulas?

It can support CPB and ECMO sizing reference workflows, but final device selection should follow manufacturer specifications.

What flow units are supported?

The flow converter supports L/min input and outputs mL/min and mL/kg/min.

Perfusion Unit Converter

Unit converter

Inputs

Outputs

Inputs

Outputs

Clinical

Gas supply

Cannula / Catheter Size

Outputs

Cannula & Tubing Size Converter

Unit Converter FAQ