Enter the FEV1 and FVC into the calculator to determine the FEV1/FVC ratio. This calculator can also calculate any one of the variables if the other two are known.

Fev1/Fvc Ratio Calculator

Calculator
Interpretation

Enter any 2 values to calculate the missing variable.

Medical note: This calculator is for educational screening only and is not a diagnosis. Spirometry should be performed with quality checks and interpreted by a qualified clinician using appropriate reference values (e.g., LLN/z-scores) and, when relevant, post‑bronchodilator results; seek medical care for concerning symptoms such as shortness of breath, wheeze, chest tightness, or chronic cough.

Fev1/Fvc Ratio Formula

The following formula is used to calculate the FEV1/FVC ratio. 

FEV1/FVC = (FEV1 / FVC) * 100

Variables:

  • FEV1/FVC is the ratio of Forced Expiratory Volume in the first second to Forced Vital Capacity (%)
  • FEV1 is the Forced Expiratory Volume in the first second (liters)
  • FVC is the Forced Vital Capacity (liters)

To calculate the FEV1/FVC ratio, divide the FEV1 by the FVC, then multiply the result by 100 to get the percentage. This ratio is used in spirometry to help assess for airflow obstruction as part of a full lung function evaluation.

What is a Fev1/Fvc Ratio?

The FEV1/FVC ratio is a calculation used in spirometry to help assess lung function. It compares the amount of air a person can forcefully exhale in one second (FEV1) to the total amount of air a person can exhale (FVC). A reduced FEV1/FVC ratio can be seen with airflow obstruction, but diagnosis depends on the full spirometry report (including predicted/reference values and test quality) and clinical assessment.

How to Calculate Fev1/Fvc Ratio?

The following steps outline how to calculate the FEV1/FVC Ratio.

  1. First, determine the FEV1 value (liters).
  2. Next, determine the FVC value (liters).
  3. Next, use the formula FEV1/FVC = (FEV1 / FVC) * 100 to calculate the ratio.
  4. Finally, calculate the FEV1/FVC Ratio.
  5. After inserting the values and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

FEV1 = 2.5 liters

FVC = 3.2 liters