How to Pace a Half Marathon

Most half marathons are not lost in the last mile. They are lost in the first three, when the crowd is loud, your legs feel fresh after a taper and goal pace feels almost too easy. Pacing well is the simplest way to run a faster, happier half, and it costs nothing. This guide shows you how to pick a goal pace you can actually hold, what your splits should look like for your finish time, and how to adjust for hills, wind and fuelling on the day.

Why does pacing matter so much in a half marathon?

A half marathon sits in an awkward middle ground. It is short enough that you can run it at a fairly strong effort, but long enough that a few minutes of overexcitement early on comes back to bite. Running the first few miles 15 or 20 seconds per mile faster than planned rarely feels like a mistake at the time. It shows up around miles 9 to 11, when your pace drops and every mile feels twice as long.

Large studies of marathon results have linked steady, even pacing with faster finish times than starting fast and slowing down, and most coaches apply the same principle to the half. The goal is simple: spread your effort evenly so you have something left for the final 5K.

Should you run even splits or negative splits?

Even splits means running both halves of the race in about the same time. A negative split means running the second half slightly faster than the first. Both are good strategies. What you want to avoid is a big positive split, where the second half is much slower, because that almost always means you started too fast.

For most first-timers and newer runners, the best target is even effort with a small negative split if you feel good. The margins are small. A runner aiming for 2:00:00 might go through halfway in around 1:00:30 and come home in around 59:30. You are not trying to sprint the second half, just to finish strong rather than hang on.

How do you find your goal pace from a recent 5K or 10K?

The most useful starting point is a recent race or hard time trial, ideally from the last six to eight weeks. A widely used prediction formula, known as the Riegel formula, estimates longer race times from shorter ones. Put simply, your half marathon time comes out at roughly 4.6 times your 5K time, or about 2.2 times your 10K time. A 10K is usually the better guide because it is closer to the half in length.

Treat these numbers as a rough guide, not a promise. They tend to work best for runners who have done the endurance training for the longer distance. If this is your first half, or your longest run so far is well under 10 miles, it is sensible to start with a goal a few minutes slower than the estimate. You can always speed up in the last 5K. Going out too fast is much harder to undo.

Estimates use the Riegel formula and assume you have trained for the half distance. Real results vary with experience, course and conditions.

A good reality check is how goal pace feels in training. If you can hold it for 5 or 6 km in a tempo session and still feel in control, it is probably realistic. If it feels like a struggle after 2 km, adjust your target now rather than on race day.

What should your splits look like for your finish time?

Once you have a goal, the table below shows the pace and checkpoint times for an evenly paced half marathon. Write your 5K, 10K and 15K times on your hand or a pace band, then use them as gentle checkpoints rather than strict targets.

Splits assume perfectly even pacing over 21.1 km (13.1 miles). Being 20 to 30 seconds either side at 5K is normal and nothing to worry about.

How should you split the race into sections?

Thinking about 13.1 miles in one go is daunting. Breaking it into three parts makes the job clearer and gives you one simple focus at a time.

• Miles 1 to 3 (the first 5K): settle in. Run the first 2 to 3 km around 5 to 10 seconds per km slower than goal pace (roughly 10 to 15 seconds per mile). It should feel easy, almost too easy. Start in the right pen or near your pace group so you are not swept along by faster runners, and avoid weaving through the crowd.
• Miles 4 to 10 (5K to 16K): lock in. This is where you run goal pace and stay patient. Half marathon effort for most of us feels comfortably hard: you can say a short sentence, but you would not want to hold a conversation. Take your fuel on schedule and keep your form relaxed.
• Miles 10 to 13.1 (the last 5K): decide. At mile 10, check in. If you feel good, pick up the pace gradually, a few seconds per km at a time. If you are already working hard, holding pace is a win. Save the all-out push for the final mile.

Many larger UK half marathons have pacers carrying flags or balloons with a finish time. Running with a pace group can take the thinking out of it, but treat them as a guide. Pacers may run slightly differently from your plan, and it is fine to drop back if their pace feels too hard early on.

How do you pace hills on a half marathon course?

Check the course profile before race day so the hills do not surprise you. On the day, the golden rule is to keep your effort even, not your pace. Going uphill, shorten your stride, keep your arms moving and accept that your pace will drop for a minute or two. Trying to hold goal pace up a steep climb can cost far more energy than the few seconds it saves.

At the top, give yourself 20 or 30 seconds to settle your breathing before getting back to goal effort. On the way down, let gravity do some of the work with quick, light steps, but do not throw yourself down the hill. Whatever time a hill costs you, spread it back over the remaining miles rather than chasing it in the next kilometre.

How do you pace a half marathon in the wind?

Wind is a regular feature of UK racing, especially on coastal and exposed courses. A headwind generally costs you more time than a tailwind gives back, so the same principle applies: run by effort. Expect your splits to slow into the wind and do not panic about it.

• Check the forecast wind direction the day before and work out which sections will be into the wind.
• Into a headwind, tuck in behind a small group if you can. Sheltering behind other runners can make the effort noticeably easier.
• With a tailwind, hold your normal effort and enjoy the faster splits, rather than turning it into a sprint.
• On very windy days, consider moving your goal back a little and judging success on effort, not the clock.

When should you take gels during a half marathon?

How much you need depends mostly on how long you will be running. Faster runners finishing in well under 90 minutes may find a good breakfast and perhaps one gel or a sports drink is enough. If you will be out for 90 minutes or more, planned fuelling can help you hold pace in the later miles. A general guide often used for races of about 1 to 2.5 hours is 30 to 60g of carbohydrate per hour, but start at the lower end if you are new to it.

Many gels contain somewhere around 20 to 30g of carbohydrate, so check the label on yours. A common approach for a runner finishing around two hours is a first gel at around 40 to 45 minutes, and a second at around 75 to 80 minutes. Slower runners might add a third. Try to take them just before a water station so you can wash them down, and walk a few steps while you drink if that helps. It will cost you a handful of seconds at most.

Most importantly, practise your race fuelling on long runs. The old rule of nothing new on race day applies to gels as much as to shoes.

What are the most common half marathon pacing mistakes?

• Starting too far forward. Lining up with faster runners pulls you along. Start in your pen and let the race come to you.
• Banking time. Running early miles fast to get time in the bank usually means paying it back with interest later.
• Chasing lost seconds. After a slow mile, a hill or a busy water station, a sudden surge burns energy you need later. Ease back to goal pace and move on.
• Trusting your watch distance. Race courses are measured along the shortest possible route, and most of us do not run perfect lines, so watches often read long. Press lap at each official marker, or follow the race clock and your pace band.
• Choosing a goal from hope. A target based on a recent race or training is far more likely to work than one picked because it sounds good.

How do you practise race pace in training?

Pacing is a skill, and you get better at it with practice. In the last six weeks or so before your race, try finishing some of your long runs with 3 to 5 km at goal pace. Tempo runs at or just under goal pace also teach you what the right effort feels like. Keep most of your other running easy so you arrive at those sessions fresh.

Strength training helps too. Many coaches include one or two short strength sessions a week for runners, because stronger legs and hips can help you hold your form in the last few miles, when pacing usually falls apart.

How can Edge help you train for your half marathon pace?

Edge is a free fitness app used by 20,000+ members. With Edge Pro, from £19.99 a month with a free 7-day trial, you get a fully personalised plan across running, strength, HIIT and mobility, ready within 24 hours. Your easy runs, goal-pace sessions and strength work sit in one plan, so they work together instead of competing for your energy.

You can also message a real coach anytime, which is useful when you want a second opinion on your goal time or a pacing plan for a hilly or windy course. Edge syncs with Strava, Garmin, Apple Health and Coros, so your runs come straight in from the watch you already use.

This article is general guidance, not medical advice. If you are new to exercise, returning from injury, pregnant, or managing a health condition, speak to your GP before starting, and see a physio for any niggle that does not settle.