While I'm at the start of my training, I need to decide how fast I intend to be able to run the marathon. I've got about 40 weeks to get as fit and fast as I can be, so let's run some numbers and see where I get to.

The site of choice for these kinds of things is McMillan Running. On this site you can enter how quickly you currently run a certain distance, and it tells you how quickly you should be able to run other distances. Or you can tell it how quickly you want to be able to run a certain distance, and it tells you what other pace you should be aiming for in other distances. 

For example, if I said I wanted to run the London Marathon in 5 hours...


Well that looks quite doable. 5 miles at a 10:13 pace isn't too far off what I'm doing at the moment, and I've still got plenty of time. I don't think this is ambitious enough though. I wasn't particularly fit at my last half marathon (although admittedly I was fitter than I am now) and I managed that in 2 hours. 

So if I feed in "2 hours" for the half marathon time, what time does it say I could do for a whole marathon?


So if I get as fit as I was under 2 years ago, I would be able to run the marathon in about 4 hours and 13 minutes. That would be amazing!

But what if I went further, could I manage below 4 hours?


That one looks a bit aspirational, but not impossible. 1:54 is my best half marathon time from several million years ago, and I do have plenty of time to train.

So to answer my original question then, I think, at the moment, I'd be disappointed with anything above 5 hours. I'd be over the moon at anything under 4, and happy with anything between 4 and 5.

Let's see what happens shall we?