Heart & coagulation

von Willebrand factor activity (RCo) unit converter

Ristocetin cofactor activity of von Willebrand factor

Also known as: Ristocetin cofactor, vWF:RCo, VWF activity

Converter

Enter a value in any unit and all other units fill in.

IU/mL % = IU/dL

Worked example

95 % (middle of the reference range) = 0.95 IU/mL

Conversion formulas

IU/mL	IU/mL = % × 0.01	% = IU/mL × 100

Good to know

The ristocetin cofactor activity of von Willebrand factor is reported in % or in IU/dL (identical) or IU/mL.

1 IU/dL = 1 %; 1 IU/mL = 100 %.
People with blood group O have lower values, which can mimic mild disease.

Reference range

Unit	Adults
IU/mL	0.4 – 1.5
% = IU/dL	40 – 150

Source: Newcastle Hospitals Laboratories: Ristocetin co-factor · Last reviewed: 2026-10-19

Note from the source: 40-150 IU/dL (= 40-150 %) (Newcastle Hospitals Laboratories); blood group O has lower values. Part of the von Willebrand screen

Frequently asked questions

How do I convert von Willebrand factor activity (RCo) from % to IU/mL?

IU/mL = % × 0.01. In the other direction: % = IU/mL × 100.

What is the reference range of von Willebrand factor activity (RCo)?

For adults the range is 40 – 150 % (Newcastle Hospitals Laboratories: Ristocetin co-factor). Reference ranges differ between laboratories and partly by sex and age; use the range printed on your lab report.

Which units are used for von Willebrand factor activity (RCo)?

Common units are IU/mL, %.