You’ve got your target marathon booked, and your target times set, now you need to decide the training time frame. How long do you need to prepare for your race? Let’s find out.


How fit are you right now?

When determining how long the build up needs to be, we first need to consider your current level of fitness. The further you are currently from your target marathon pace, the longer you’ll need in training. Perhaps not the 12-16 week marathon specific block, but in the faster miles before this.

You can use a 10k to 10 mile test run to gauge how prepared you are right now, then factor in that most people’s projected marathon times end up being slower come race day as marathon training has far more variables and is harder to get right.


How specific can your training be?

If you have limited time and can’t run as many miles as you’d like to, then you’ll need a longer build-up. If, on the other hand, you have great flexibility in your work and personal life allowing you to choose what types of runs you do and when, you’ll be able to cut down on the number of weeks of training.


How long are your runs outside of marathon training?

Outside of marathon training, most people tend to drop to 8-10 miles as their longest weekly run. This is understandable, but unhelpful when looking to decrease your marathon time in the longer term. More on this later.


If your last marathon is your current PB, how well did it go?

Between inadequate fuelling, bad weather, an upset stomach or a bug in the latter weeks of training, your current PB marathon could have still not gone to plan. If that’s the case, you can potentially stick to the same length of training that worked well last time, but look to improve the factors that are in your immediate control such as nutrition, active recovery and strength training. If, however, it went off without a hitch then it’s time to raise your game.


Are you seeking expert guidance?

If you’re working from a template or cookie-cutter type programme from a running magazine, book or guru which promises you a certain time if you follow their one-size-fits-all plan, then my advice is firstly to ditch this in favour of a personalised one from a club or professional coach if possible. 

The less tailored the programme, the longer you’ll need to train for your race if you’re to hit your target time.


So, how long do you need to train for a marathon PB?

I’d advise at least 6 months generally speaking. This gives you 6-8 weeks to focus on increasing speed to reach the time needed to predict your marathon target time, e.g. to run a sub 4 hour marathon, you theoretically need to run a 51:45 10k or 1:25:46 for 10 miles, although realistically you’ll likely need to run closer to 51:00 and 1:25:00. Always be over-prepared.

Next comes 12-16 weeks of building up the long run mileage gradually, perhaps even running the same distance two weeks in a row as you progress. This part goes better if you’ve kept to 12-13 easy miles as your weekend longer run since your last marathon.


Consider all of this these topics when deciding on the start date for your marathon training and you’ll stand a far better chance of succeeding when race day arrives.


Written by Kyle Brooks, Running Coach based in Norwich, Norfolk