FEV1 / FVC ratio

Last reviewed 07/2021

The FEV1/FVC ratio is the ratio of the forced expiratory volume in the first one second to the forced vital capacity of the lungs.

The normal value for this ratio is above 0.75-85, though this is age dependent.

  • values less than 0.70 are suggestive of airflow limitation with an obstructive pattern
  • restrictive lung diseases often produce a FEV1/FVC ratio which is either normal or high


  1. The Practitioner 2005; 249:180-88.