Easy-medium. Sub-threshold. Comfortably fast. You hear lots of phrases used to describe half-marathon pace but let’s discuss some specific ways to determine your best half-marathon race pace—and then how to confirm that the pace is possible on race day.
Nail your pace, and the half marathon can be the most satisfying of races, run at a fast-but-fun level of effort that makes you feel invincible and amazed that you can hold it for so long. A bit too fast and those wheels fall off somewhere in the middle, leaving you to slog some hard miles to the finish. Hold back too much and you’ll finish fine, but may be kicking yourself as you realize how much you have left in the last three miles.
Part of the reason that half-marathon pace is such a weird pace for many runners is that it lies between two key thresholds: The anaerobic or lactate threshold and the aerobic threshold. The lactate threshold is roughly one-hour race pace (half-marathon pace for really speedy runners, but too fast for most) whereas the aerobic threshold is roughly two and a half hour race pace (half-marathon pace for some of us, but a bit slow for many—and marathon pace for a few up front).
Since half-marathon pace falls somewhere between those two thresholds for most of us, it makes it a hard pace to “feel.” Running close a threshold is much easier for most runners. That’s why having a good estimate of goal pace and then practicing it in training is an absolute requirement to be ready for your best performance on race day.
Step #1: Use Calculators & Calculations
To help my runners determine their best half-marathon pace, I created the McMillan Running Calculator. You simply insert a recent race time (could be a 5K or 10K or any other race distance) and the calculator predicts what you can run for the half-marathon.
Several online pace calculators are now available and one of the most common (and powerful) strategies for determining a good half-marathon goal pace is to use another race performance to predict your half-marathon time and thus get your pace. To get a better estimate, use multiple races over different distances, which helps average out one exceptional day and provides a more generalized picture of your overall race fitness.
Before online calculators, however, many of us used rules of thumb passed down from great coaches and athletes. Here are a few that I find work well:
- Take your 10K time, double it and then add 10–15 minutes:
For example, if you run 45 minutes for a 10K, then double that time (which equals 90 minutes) and then add 10-15 minutes. A reasonable half-marathon goal time for a 45-minute 10k runner using this method is 1:40–1:45.
Note: I find that for faster half-marathoners (sub 1:30), adding 10 minutes (or even seven minutes for really fast runners) to the doubled 10K time works, whereas for slower runners (around two hour half-marathoners), adding 15 minutes to the doubled 10K time works well. This correlates to adding roughly 10 percent of the doubled 10K time, if you want to do a bit more math.
- Take your 10K race pace and add 15–30 seconds per mile:
Another easy rule for thumb is to take your current 10K race pace and add 15–30 seconds per mile. For example, if your 10K race pace is eight minutes per mile, then a good estimate of your half-marathon pace is 8:15–8:30 per mile. Faster runners find 15 seconds per mile works whereas slower racers, find 30 seconds per mile works. Those who want to do the math can convert the 10K pace to seconds and add roughly 5 percent to get the half marathon pace.
- Take your marathon race pace and deduct 15–30 seconds per mile.
The final rule of thumb that I’ve used is to take your marathon pace and deduct 15–30 seconds per mile. For example, if your marathon pace is 8:30 per mile, then your estimated half-marathon pace would be 8:00–8:15 per mile. Again, faster runners find the 15 seconds per mile works for them and slower runners find 30 seconds per mile works best. The math here works out so that half marathon pace is roughly 95 percent of marathon pace.
As with all things running, however, you must experiment to see what works best for you. Some runners are faster at shorter distances and have trouble holding on. Some can maintain close to the same pace even when they double the distance. The type and volume of your training will also influence how fast you can run at different distances. These estimates will help you narrow the pace, then you need to test the estimate.
Step #2: Do Goal Pace Workouts
Getting a rough idea of what pace is possible is step one, but I then recommend athletes do a series of goal pace workouts across their training plan to really dial in whether the predicted pace is doable or not (and, if not, figure out what pace is more doable).
Three of my favorite goal pace workouts are:
2–3 X 3 miles, run at goal half-marathon pace, with 2–3 minutes recovery jog between each repeat.
Do this workout about eight weeks before your race. For some runners, this workout can be a shock to the system, and they wish goal pace didn’t feel quite as fast. But, stick with it. The first goal pace workout often feels tough, but you’ll receive a big mental and physical boost after simply completing this workout. I never invest too much into this workout or abandon the goal pace unless the runner simply can’t hit goal pace for any portion of the workout.
2 X 4 miles, run at goal half-marathon pace, with 2–3 minutes recovery jog between repeats.
Do this workout around four weeks before your race. By the time you get to this workout, you should find that the first repeat is comfortable and it’s only toward the end of the second repeat that you begin to feel fatigue. If you struggle to hit the pace even in the first repeat, then it’s time to adjust your goal pace. Again, these goal pace workouts are essential for helping you dial in your pace. Listen to your inner coach and be honest with yourself. If the pace feels just too fast for 13.1 miles, then be open to adjusting. Sometimes, just a slight adjustment of a few seconds per mile can make the workout successful.
6–8 miles, run at goal pace.
Perform this workout 2–3 weeks before your race. This final goal pace run should feel like a mini version of the half-marathon. You should find that the first 2–4 miles feel very comfortable. Then, past halfway, you have to raise your mental intensity to hold the pace for the final 2–3 miles yet still finish feeling like you could have done another 1–2 miles at goal pace if asked to.
When I have an athlete that can hit goal pace in all three of these workouts, I feel very confident she can run it on race day. If she can’t nail the workouts, then it’s time to adjust the goal pace.
Step #3: Fix Your Faults
As you look ahead to your half-marathon training and racing, think about the limitations you’ve discovered in your prior training/racing. You might be surprised how just a few “weakness” workouts significantly improve that aspect of your fitness and pay big dividends on race day.
- Fading late in the race? Do more volume (higher mileage and/or run more days per week) and progression runs (finishing faster than you started).
- Does half-marathon pace feel fast? Do more speed work to make goal pace feel easier.
- Have a hard time staying on pace? Do more goal pace running.
- Legs fatigued, sore, cramping later in the race? Do more uphill and downhill training, longer long runs and strength training to build stronger legs.
You don’t have to completely abandon the workouts in your plan, but slotting in a few workouts to address your weaknesses helps your goal finish time become more likely.
Step #4: Practice the Correct Type of Suffering
These days, it seems like we are doing everything we can to avoid suffering in training. From fueling to springy shoes to “hacking” training, runners are looking for a way to avoid suffering. But suffering is part of racing your best. Therefore, another key to improving the odds of hitting your goal time is to practice the correct type of suffering.
In the half-marathon, the suffering is not so much due to the speed of the race but to the duration. After over an hour of running, the muscles begin to fatigue, and your mind starts to create more and more fatigue messages. This fatigue is slightly different than the fatigues most of us are used to: Fatigue that stems from a short race or that of an easy long run. Instead, we need to get used to a “grinding” suffering, which is what most of us feel over the last 3–4 miles of a half-marathon.
In your training, include some workouts that focus as much on creating race-specific suffering as hitting certain paces. Long, goal-pace runs, fast-finish long runs, and pushing hard the last few repeats of hill workouts and speed workouts can help condition your brain to the suffering you will face on a race day. The more this suffering becomes normal, the less the brain will complain on race day, helping you win the battle between the ears.
Step #5: Listen to Your Inner Coach
No crystal ball exists to know exactly what an athlete can run on race day. There are just too many variables that can affect race day performances.
I would leave you with the reminder to listen to your inner coach as you train so you find a realistic goal pace. Most runners have an intuitive sense of what is reasonable on race day after doing these goal pace workouts but often their desire for a time can cloud their judgment and they ignore their inner coach that nearly always knows best. Adjust your goal pace if you need to, and when you accomplish the goal workouts at this pace, you can head into the race with high confidence that you can achieve your goal time.
Top performers also hone the intuitive ability to modify goal pace based on how they feel on the day, the weather conditions, the terrain, the competition and any unexpected complications. This is another critical component to racing your best over the half-marathon distance.
After all, not every racecourse or weather condition or how you feel will be conducive to running a personal best. Instead, I recommend focusing on how you can run to get the most from that particular day, whether you feel like a million bucks or like a sack of loose change.
Ever notice how the best runners seem to perform well no matter the conditions or how they feel on race day? ? Instead of giving up, they adjust. They compete, and, when they’re done, they knew they did their best for that day.
The rest of us should follow their lead. If we did, we’d always be at least satisfied that we did our absolute best even if it wasn’t the time we hoped for.