How do I pick a realistic finish time?
Short answer
Start from a recent race or timed run and scale it to the new distance. With no recent time, leave a rough guess or make finishing comfortably your goal; your plan will tell you how realistic it looks.
Key points
- A recent result at a shorter distance is the best guide you have.
- Times scale a little worse than distance: twice as far takes a bit more than twice as long.
- A rough guess is fine. The plan checks it and says if it looks too ambitious.
If you have a recent time
Use a race or a hard timed run from the last few months. A widely used rule of thumb, Riegel's formula, says that when the distance doubles, the time goes up by a little more than double:
new time = old time × (new distance ÷ old distance)^1.06
For example, a 10K in 55:00 points to a half marathon of about 2:01. A half in 2:00 points to a marathon of about 4:10.
Treat the result as a ceiling
The formula assumes you train properly for the longer distance. For a first marathon, or if your long runs are short, add a few minutes per hour of racing.
If you have no recent time
Enter a rough guess. For a first race, finishing comfortably is a good goal. Your plan sets your training from where you are now, not from the goal alone.
In your plan
Your target time sets the paces for your harder sessions. If it looks out of reach in the weeks you have, the plan says so in its summary, and you can edit the goal at any time.
Related questions
5K, 10K, half or marathon: which should I train for first?
Pick the distance you can train for safely in the weeks you have. For most people starting out that is a 5K or 10K; a half or full marathon makes sense once you already run several times a week.
Read the full answerHow many weeks do you need to train for each distance?
From a base of running a few times a week, allow about 6–8 weeks for a 5K, 8–10 for a 10K, 10–14 for a half marathon and 16–20 for a marathon. Starting from scratch, add several weeks.
Read the full answerWhy should easy runs feel slow?
Because most of your fitness comes from running easy, often. An easy run should let you talk in full sentences. Running it harder makes you more tired without making you much fitter.
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