The fev1/fvc ratio calculator takes fev1, fvc, age, height, e and one way and returns predicted fev1/fvc and fev1/fvc. It is built for quick answers, for checking somebody else’s arithmetic, and for the moments when a formula book is not within reach.
What Is the Fev1/fvc Ratio Calculator?
The fev1/fvc ratio calculator gives you an estimate of predicted fev1/fvc and fev1/fvc based on fev1, fvc, age, height, e and one way.
It is a quick reference figure rather than a diagnosis, and it is most useful for tracking how a number moves over time rather than for interpreting a single reading.
How the Fev1/fvc Ratio Estimate Is Worked Out
The calculation follows published reference relationships, so it is a reasonable approximation when the inputs are accurate. It assumes an average adult and does not account for individual variation.
If you are comparing two people, or the same person over a period of weeks, keep the method and the inputs identical. A change in the method can easily look like a change in the person.
What This Calculator Does Not Do
It does not diagnose anything, and it does not replace advice from a clinician. If a figure comes out at an extreme, or if it differs sharply from what you expect, that is a reason to speak to a professional rather than to adjust the inputs.
Nothing you type here is stored or sent anywhere. The whole calculation happens in your browser.
A Worked Example
Working through an example, with fev1 set to 10, fvc set to 5, age set to 2, the calculator returns fev1/fvc of 2, and predicted fev1/fvc of 1.08356, and predicted fev1/fvc (index eng woman) of 1.12995. Substitute your own figures and the same steps produce the same kind of answer.
Frequently Asked Questions
What do I need to work out predicted fev1/fvc?
Enter fev1, fvc, age, height, e and one way. The calculator then works through the relationship and reports predicted fev1/fvc and fev1/fvc.
What does the fev1/fvc ratio actually calculate?
It takes fev1, fvc, age, height, e and one way and converts them into predicted fev1/fvc and fev1/fvc using the standard relationship for this problem. Each step is applied in turn, so every output is traceable back to the numbers you typed in.
How should I enter fev1?
Use the value you actually have, in the unit shown next to the field. Enter every value in the same unit system. The calculator assumes the figures you supply are consistent, so it cannot correct a mistake that happens before the calculation starts.
Can I use this for a quick estimate as well as a precise answer?
Yes. The calculator is built for quick checks, so round your inputs to a sensible number of significant figures and the result will be just as useful. If you need more precision, keep the same method and add digits to the inputs rather than adjusting the method itself.
Does anything you type get stored?
No. The whole calculation runs inside your browser, and nothing you enter is uploaded, logged or sent anywhere.