Blood gases & acid-base

Carboxyhemoglobin unit converter

Hemoglobin bound to carbon monoxide (non-smokers; smokers up to ~10%)

Also known as: Carboxyhaemoglobin, COHb, HbCO, Carbon monoxide hemoglobin, Carboxyhémoglobine, Carboxihemoglobina

Converter

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

fraction %

Worked example

1 % (middle of the reference range) = 0.01 fraction

Conversion formulas

fraction	fraction = % × 0.01	% = fraction × 100

Good to know

Carboxyhemoglobin is reported in % or fraction. The page converts between the units only.

fraction × 100 = % (exact factor 100).
The range shown is a guide from the named source; targets and reference ranges differ between laboratories, methods and indications, so compare with the range on your own report.

Reference range

Unit	Adults
fraction	0 – 0.02
%	0 – 2

Source: Newcastle Hospitals Laboratories: Carboxyhaemoglobin, blood · Last reviewed: 2026-10-19

Note from the source: Non-smokers below 2 %, heavy smokers below 8 % (Newcastle Hospitals Laboratories)

Frequently asked questions

How do I convert Carboxyhemoglobin from % to fraction?

fraction = % × 0.01. In the other direction: % = fraction × 100.

What is the reference range of Carboxyhemoglobin?

For adults the range is 0 – 2 % (Newcastle Hospitals Laboratories: Carboxyhaemoglobin, blood). Reference ranges differ between laboratories and partly by sex and age; use the range printed on your lab report.

Which units are used for Carboxyhemoglobin?

Common units are fraction, %.