Stupid Question Time Re: VO2max

I was reading an article that referenced VO2max and I'm just trying to translate it in my head in order to help myself understand the ideas being presented.

So, I found the following web page with a VO2max calculator that does not require any physical exertion. (I know that this isn't going to be the most accurate thing in the world. I am just trying to get a basic understanding going, here.) Here's the link:

http://www.shapesense.com/fitness-exercise/calculators/vo2max-calculator.aspx

So, now for the stupid question...Am I calculating this correctly?

I visited the doctor recently and my pulse was 66 beats per minute. So, if I divide that by 3, I get 22 beats in 20 seconds, and if I plug that into the calculator along with my age it gives me an estimated VO2 max of 41 ml//kg/min. When I click the explanation link it reports that rate to be "excellent", which I am dubious about. I do walk a lot, but I am not an athlete.

I could also dig out my heart rate monitor, later. I think that I remember reading in the instructions that there is a VO2max estimate setting. But right now I can't do it. And, if I am really feeling motivated, later, I could do the one mile walk test. But, for now, I am just trying to quickly wrap my head around the article.

Bottom line, did I do the rough estimate calculation above correctly?