A half marathon training plan built around your race

What does a half marathon training plan look like?

A half marathon plan is built around one long run a week that grows gradually, one quality session (tempo or intervals) and easy runs that make up most of your distance. Every fourth week is lighter, and the last two weeks taper so you start fresh.

Keeping most running easy is not a beginner compromise. Stephen Seiler's 2010 review of how successful endurance athletes train found that roughly 80% of sessions were done at low intensity, with the hard work concentrated in a small share of sessions. The journal follows the same idea: one hard run a week, everything else easy. Below is the 14-week plan for a first-timer running four times a week.

The quality session alternates. Tempo runs (10 minutes easy, then about 20–40 minutes at a comfortably hard pace, 10 minutes easy) make race pace feel easier. Intervals of 1 km with a 2-minute jog, building from 3 to 6 repeats, raise your top-end speed. The first two weeks use short strides instead, so your legs adapt before the harder work starts.

Half marathon training plan for beginners

If this is your first half, you need to be able to run about 5 km without stopping, then allow at least 8 weeks, and ideally 12–16, to build up. Three runs a week is enough to finish well; four gives you more margin.

First-timers start with an 8 km long run and build to 18 km rather than the full distance. Race-day adrenaline, the taper and a sensible pace carry you the last 3 km, and skipping a 21 km training run removes a big injury risk. Your easy runs should feel conversational, and walking briefly on hills or to take a drink is completely fine.

Two 15-minute strength sessions a week (squats, lunges, calf raises, glute bridges and a plank) are part of every week. They are short, but they help your legs handle the extra kilometres.

• Increase weekly distance by no more than about 10% unless it is a planned build week
• Keep an easy day or rest day after every long run
• If you miss a week, repeat the previous week rather than jumping ahead
• A niggle that changes how you run means two easy days or cross-training, not pushing through

What is my half marathon pace?

Your realistic half marathon pace comes from a recent 5 km or 10 km race, run through the Riegel formula: predicted time = known time × (21.0975 ÷ known distance)^1.06. A 55-minute 10 km predicts about 2:01:21, or 5:45 per km.

Training paces then follow from race pace. In the journal, easy runs are about 22% slower than race pace, long runs about 18% slower, tempo runs about 4% faster and 1 km intervals about 10% faster. The prediction assumes you complete the training, so treat it as a target to grow into. Try the free half marathon pace calculator with your own time.

How to run a sub 2 hour half marathon

To run a sub 2 hour half marathon you need to average just under 5:41 per km (about 9:09 per mile); the splits below use 5:40 per km for a small buffer. By the Riegel formula, that is realistic if you can currently run 10 km in about 54:20 or 5 km in about 26:05, and you complete the training.

If your current times are a little slower, a 12–16 week plan with consistent long runs and weekly tempo work can close a gap of a few minutes for many runners, but no plan can promise it. Retest a 5 km or 10 km at mid-plan; if your predicted time drops under 2:00, run the race at that pace. Start the first 3 km 5–10 seconds per km slower than goal pace, then settle in. Even splits beat a fast start almost every time.

How long should my longest run be before a half marathon?

For most runners the longest run should reach 18–20 km about three weeks before race day. First-timers in the journal peak at 18 km; runners with a half behind them peak at 20 km.

Run long runs at easy to long-run pace, not race pace. In the last six weeks before the taper, the journal adds a race-pace finish to the long run (for example the last 5–8 km at goal pace) so you practise holding pace on tired legs. Cutback weeks shorten the long run by about a quarter, and the second-to-last week drops it to 12 km.

If you are a slower runner, think in time as well as distance. An 18 km long run at 7:30 per km takes well over two hours, so keep the pace genuinely easy, take carbohydrate from about 45 minutes in and walk briefly to drink. The aim is to arrive at race week having practised the duration, your fuelling and your shoes, not to prove you can already race the distance.

Fuelling and race day

Practise race-day fuelling on your long runs so nothing on the day is new. On runs over 75 minutes, take in 30–60 g of carbohydrate an hour, from gels, chews or a sports drink, and drink to thirst.

Use your three longest runs as dress rehearsals: the same shoes, kit, breakfast and gels you plan to use on race day.

• Eat a mostly carbohydrate breakfast 2–3 hours before the start
• Start 5–10 seconds per km slower than race pace for the first 3 km
• Take your first gel around 40–50 minutes in if you use them
• Nothing new on race day: same shoes, same gels, same breakfast

Common half marathon training mistakes

Most half marathon plans go wrong in one of three ways: easy runs that are too fast, long runs that jump too quickly, or skipping the taper. Each one is easy to see in a run log.

• Running easy days at tempo pace. The hard sessions only work if the easy ones are genuinely easy.
• Adding distance too quickly. Big jumps in weekly kilometres are a common route to shin and knee problems.
• Treating cutback weeks as optional. They are where the fitness from the previous three weeks sinks in.
• Panicking in the taper. Fitness does not disappear in two weeks; fatigue does.
• Neglecting sleep and carbohydrate in the peak weeks. They are your best recovery tools.

Updated October 18, 2026 · Written by the Kilopace editorial team