How to Go From 5K to Half Marathon

By Haleigh Hockenberry ·


Completing a 5K is a major accomplishment, but many runners eventually start looking for a bigger challenge. If you've successfully finished a 5K and are wondering how to go from a 5K to a half marathon, the good news is that the transition is more achievable than you might think.


The key is gradually building endurance while maintaining consistency and staying healthy throughout training. With the right approach, most runners can progress from running 3.1 miles to 13.1 miles in just a few months.


Build Your Weekly Mileage Gradually


The biggest difference between 5K training and half marathon training is the amount of running required. While 5K training often focuses on speed and shorter workouts, half marathon training emphasizes endurance.


Rather than making large jumps in mileage, gradually increase your weekly running volume over time. This helps your muscles, tendons, and cardiovascular system adapt to the additional workload.


One of the most important tools for building endurance is the easy run. Easy running develops aerobic fitness while minimizing fatigue and injury risk.


Prioritize Long Runs


Long runs are the foundation of half marathon training. They help your body adapt to spending more time on your feet and improve your ability to maintain a steady pace over longer distances.


If you're comfortable running a 5K, you don't need to jump straight to double-digit runs. Instead, gradually extend your longest run each week.


A typical progression might look like:



Most half marathon training plans peak with a long run of 10–12 miles before race day.


Add Tempo Runs for Endurance


While long runs build aerobic capacity, tempo runs help improve your ability to sustain faster paces for extended periods.


Tempo runs are often performed at a comfortably hard effort and can increase your lactate threshold, making race pace feel easier on half marathon day.


Many runners include one tempo workout per week alongside their easy runs and long run.

Learn more in our Tempo Run Guide.


Learn Your Half Marathon Pace


Many runners train too fast or too slow because they don't understand their target race pace.


A realistic half marathon pace should feel challenging but sustainable. Understanding pace helps you train more effectively and avoid race-day mistakes.


Our guide on How to Find Your Race Paces explains how to determine training and racing paces based on effort and current fitness.


Don't Neglect Nutrition and Recovery


As training volume increases, recovery becomes more important. Proper nutrition helps replenish glycogen stores, repair muscle tissue, and support adaptation from training.


Focus on:



If your long runs begin approaching 90 minutes or more, fueling during runs may also become beneficial.


Stay Healthy Throughout Training


One of the most common mistakes runners make when moving from a 5K to a half marathon is increasing mileage too quickly.


To reduce injury risk:



Our Strength Training for Runners and Injury Prevention for Marathon Runners guides can help you stay healthy while building endurance.


Take the Next Step


Going from a 5K to a half marathon is less about speed and more about consistency. Runner's World's guide to training from 5K to half marathon explains that most runners make the transition successfully by gradually increasing weekly mileage while keeping the majority of runs at an easy, conversational effort. By focusing on easy runs, long runs, smart workouts, proper recovery, and gradual mileage progression, you'll build the endurance needed to successfully complete your first half marathon.


With patience and consistent training, the leap from 3.1 miles to 13.1 miles is entirely achievable and often becomes the first step toward even bigger running goals.