You can easily do the math and figure you that you need to average a bit over 20 miles per day. I guess the question is about the reality of actually doing that on the AT.
I thru hiked the AT in 3.5 months a couple years ago. I was 51 at the time and my partner was 63. We had a great time. Your plan is ambitious and difficult, but it is possible if you do everything right and stay whole and healthy.
Experience was as much an issue for us as fitness was. The AT was not our first 2000+ mile hike. In addition to being able to hike 25+ mile days consecutively, you have to be able to stay healthy and keep up the pace week after week. What helps the most is really enjoying the hike–the mental aspect. If you’re having a good time, the rest comes easy.
When you start long distance hiking, there’s a tendency to pace too fast and end up with skin problems like blisters, rashes or boils, and that could take days to recover from.
You also need to minimize your time spent on logistics. You need to be able to get into town, buy groceries and do laundry, and get back out–no futzing around waiting for the PO to open the next day, exchanging gear that doesn’t quite fit or work right, etc. You’ll be real lucky if you get all that right on your first try. For example, it took me 2000 somewhat painful miles to find the right shoes.
And being out for a month you’ll need to be able to eat and hydrate right for the long term. That often takes some experience to figure out. That will go a long way to keeping you healthy, happy, and out on the trail.
Have you ever hiked these kind of miles? I’d really recommend you try at least one 100 mile hike in four days (or similar) as a shake-down before you head off. If you’re to be successful in your AT plans, you’ll need to be doing that routinely.
By the way, parts of the AT are simple compared to others. I’m sure you can look at a trail profile and figure that out. I was averaging nearly 30 miles per day in the mid-Atlantic (strolling into a restaurant or ice cream shop every day), but more like 15 in rugged wilderness NH and ME.
Good luck and have fun!
Garlic