Converting parts-per-million (ppm) to percentage (%)

In the calculator below we have created a calculator to convert parts-per-million (ppm) into percentage (%).  For those interested in a brief discussion on ppm please see the DISCUSSION on this page.


The calculator below was designed by Zimmer and Peacock to allow us to quickly convert between ppm and percentage when thinking about carbon dioxide on the breath, but the calculator can be more more widely used.


In simple/general terms the air we breath in is about 0.04% carbon dioxide, and the air we breath out is 4 %, so clearly there is a 100 fold increase between inhaled breath and exhaled breath.


Part-per-million (ppm) is a widely used unit and often miss understood unit.  Whenever  one is confronted with the units ppm, one of the first things one might want to consider is are the ppm units in fact part-per-million by volume (ppmv) or part-per-million by mass (ppmw).. When people report ppm they are in fact often meaning ppmv or ppmw. For the calculator on this page the calculator works irrespective of ppm, ppmv, or ppmw.  Please if you would like help on a specific problem please feel free to contact us.    2022