Uh, on that note-
Dudes, you all need to RELAX!
The marathon will come to you, you cannot rush it. So all this worry about "how do I know how to pace myself" nonsense going around, is just that... nonsense. Listen to your body and you will know the answer to your pace.
I recommend running your first marathon at what I like to call your "happy pace". If you are going out of finish, then you should look back through your training log/run journal (you are keeping one right? along with a food journal/diary?) and look at your average for your 16, 18, 20 milers.
For me, on my first marathon, this would have been around a 10:30/11 minute pace. And yet somehow I thought that I was going to head out on race day and run a blistering 9:50 pace. The reason? Well one of those online calculators said I could, based on my Half Marathon PR.
Never mind that when I ran that Half Marathon I was trained to perfection, had peaked at the right moment, the weather was more than perfect, and was doing the hilliest routes I could find to prepare for a pancake flat course. I somehow thought that because that calculator said it, it would happen.
Consequently, I went out a bit too fast.
(snicker snicker... that's probably the understatement of the century right there)
So for those of you looking to FINISH your first race in a way that makes you proud, accomplished, have you smiling at the end, and, probably the most important thing of all, shouting from the rooftops that you are a MARATHONER, might I suggest just taking for what it is?
A 26.2 mile learning experience.
Because nothing you ever do before hand will prepare you for the things that will happen on race day. Some of you will go out and have a PERFECT DAY. Some of you will not. There is no telling which of you will fall into one category or the other. But at the end of the day, if you run your happy pace for the first 20 miles or so, you will finish the race, and you will be a MARATHONER.
AND no one, and I mean this, even an elite level athlete, is going to EVER say, "oh, you only ran your first marathon in XYZ amount of time?" No I assure you, what people will say when you mention that you ran a marathon is:
"Holy CARP, seriously? YOU are AMAZING! Did you know that only less than 1% of the population will ever do that?"