If you are new to racing, the first thing you ask is how many km is a half marathon. The precise answer matters for training, pacing, and fueling. You will see guides that round numbers, yet accuracy helps you plan every split. In this article for smartcric.buzz, we break down a half marathon in km, convert the distance to miles, and show how to pace your run without stress.
Many runners also search how many km in half marathon while building their plan. Others ask how many miles is a half marathon because their watch shows miles by default. We cover both. You will also learn how half marathon distance compares with a full race and how far is a marathon and half marathon when listed side by side.
How many km is a half marathon | The quick answer
How many km is a half marathon exactly? The official distance is 21.0975 km. Organisers and training apps usually round it to 21.1 km for convenience. If you prefer miles, the same course equals 13.109 miles, which most runners write as 13.1 miles. Knowing the exact number keeps your plan precise when you build splits and nutrition.
When you see half marathon in km printed on event pages, the course has already been measured to certification standards. That is why your watch might show a small variance on the day; GPS drift and wide cornering can add metres even though the route is correct.
Marathon vs half | How far is a marathon and half marathon?
- Half marathon distance: 21.0975 km (13.109 miles)
- Marathon distance: 42.195 km (26.219 miles)
Therefore, how far is a marathon and half marathon when compared directly? The full marathon is exactly double the half marathon. This ratio matters when you plan weekly mileage and long-run length. If you know how many km is a half marathon, you can scale workouts realistically and protect your recovery.
Why the exact number matters for pacing
Runners who understand how many km in half marathon build better pacing habits. A small mistake early can snowball over 21.0975 km. Even splits conserve energy, while erratic surges burn glycogen and raise heart rate. Moreover, precise distance helps you time gels and plan water stops.
When friends ask how many miles is a half marathon during training, tell them 13.109. That number makes your pace conversions accurate and keeps group runs on track.
Pace table | Match your goal to an even split
Use this table to convert finish goals to pace per km and pace per mile. It is built around the official half marathon distance of 21.0975 km.
| Finish time | Pace / km | Pace / mile |
| 1:20 | 3:48 | 6:06 |
| 1:25 | 4:02 | 6:29 |
| 1:30 | 4:16 | 6:52 |
| 1:35 | 4:30 | 7:15 |
| 1:40 | 4:44 | 7:38 |
| 1:45 | 4:59 | 8:01 |
| 1:50 | 5:13 | 8:23 |
| 1:55 | 5:27 | 8:46 |
| 2:00 | 5:41 | 9:09 |
| 2:05 | 5:55 | 9:32 |
| 2:10 | 6:10 | 9:55 |
| 2:15 | 6:24 | 10:18 |
| 2:20 | 6:38 | 10:41 |
| 2:25 | 6:52 | 11:04 |
| 2:30 | 7:07 | 11:27 |
Print this chart or save it to your phone. Seeing the number keeps how many km is a half marathon front of mind and helps you settle into rhythm quickly.
Example split plans for popular finish goals
Below are checkpoint times for evenly paced efforts. They reference half marathon in km markers at 5 km, 10 km, 15 km, 20 km, and the finish.
Goal 1:30 (4:16/km)
- 5 km: 21:20
- 10 km: 42:40
- 15 km: 1:03:59
- 20 km: 1:25:19
- Finish (21.0975 km): 1:30:00
Goal 1:45 (4:59/km)
- 5 km: 24:53
- 10 km: 49:46
- 15 km: 1:14:39
- 20 km: 1:39:32
- Finish: 1:45:00
Goal 2:00 (5:41/km)
- 5 km: 28:26
- 10 km: 56:53
- 15 km: 1:25:19
- 20 km: 1:53:45
- Finish: 2:00:00
Goal 2:15 (6:24/km)
- 5 km: 32:00
- 10 km: 1:03:59
- 15 km: 1:35:59
- 20 km: 2:07:59
- Finish: 2:15:00
Because how many km is a half marathon never changes, each plan works on any certified course; you just adjust for hills or heat.
Choosing a target pace that fits your fitness
Start with recent results. A fresh 5K or 10K predicts your limit better than a guess. Add a margin for endurance, then test pace during long runs. When you keep asking how many km is a half marathon, you also remember the reality of 21.0975 km: patience pays. If goal pace feels like a sprint in training, choose a safer target and enjoy negative splits.
Many runners who track in miles still ask how many miles is a half marathon for pacing. Convert once, set your watch to km for clarity, and follow half marathon in km markers on course.
Training frameworks that respect half marathon distance
You can reach the start line with three to five runs per week. These simple structures emphasise consistency and make how many km in half marathon feel manageable.
Finish strong (3 days weekly)
- Intervals: 6 × 800 m at 10K pace, jog equal time.
- Easy run: 40 to 60 minutes at conversational effort.
- Long run: 12 to 18 km, last 3 to 6 km at steady pace.
Personal record (4 days weekly)
- Tempo: 20 to 30 minutes at a comfortably hard pace.
- Easy + strides: 45 minutes easy, then 6 × 20-second strides.
- Intervals: 5 × 1 km at 10K pace, 2 minutes recovery.
- Long run: 14 to 22 km with blocks at goal pace.
High achiever (5 days weekly)
Add a second aerobic day. Keep the long run disciplined most weeks. You already know how many km is a half marathon; build your ceiling with tempo and interval quality without overdosing volume.
Strength two times per week supports form and resilience. Focus on calves, glutes, hips, and mid-back to protect your half marathon distance sessions.
Taper week | Carry freshness to 21.0975 km
Seven days out, reduce volume to 60–70% of your peak week. Keep two short tune-ups at goal pace so your legs remember rhythm. Sleep well, choose simple meals, and lay out kit midweek. When you know how many km is a half marathon, you also know you do not need extreme carb loading; steady meals work fine for most runners.
Fueling and hydration for the half marathon in km
- Pre-race meal: Eat 2 to 3 hours before the start; keep it familiar and carb-led.
- Mid-race gel: One gel around 40–60 minutes helps many athletes.
- Fluids: Sip to thirst; do not overdrink.
- Caffeine: If tolerated, a small coffee an hour before can sharpen focus.
This plan fits the time window implied by how many km is a half marathon. Practice during long runs so race day feels calm.
Gear checklist for confident pacing
- Shoes with at least one long run on them
- Technical socks to prevent blisters
- Shorts or tights that do not chafe
- Watch set to pace per km and auto-lap at 1 km
- Race belt or pins, gels, and a throwaway layer
Knowing how many km in half marathon lets you set the right data screen: current pace, lap pace, distance, and time.
Race morning routine that keeps you steady
Warm up with 5 to 10 minutes of easy jog, a few drills, and three strides. Enter the start pen early so you do not weave in the first kilometre. Run the opening 3 km slightly conservative, then settle on goal pace. Smile at cameras near 21 km and run through the line. Because how many km is a half marathon is fixed, the discipline to hold pace is the true test.
Common mistakes and how to avoid them
- Sprinting the first 5 km and paying later
- Skipping gels when your goal exceeds 1:45
- Training only long and slow, then lacking tempo economy
- Ignoring heat, headwind, or sharp hills
- Forgetting the conversion when friends ask how many miles is a half marathon
Small tweaks fix these issues fast. Keep half marathon in km on your watch, and focus on a smooth rhythm.
Course craft | Hills, wind, corners, and aid
Shorten stride uphill and stay tall downhill to save quads. Tuck behind small groups in a headwind. Choose clean lines through turns and decide about water before you reach the table. These habits protect seconds at every marker. Your understanding of how many km is a half marathon turns into smart choices across the route.
Glossary of distance phrases you will see
- Half marathon distance: the certified 21.0975 km course length
- Half marathon in km: the same figure, written for metric pacing
- How many km in half marathon: a common search phrasing that equals 21.0975
- How many miles is a half marathon: the 13.109 miles conversion
- How far is a marathon and half marathon: a side-by-side comparison of 42.195 km and 21.0975 km
This glossary keeps your terminology consistent when building a plan or writing race goals.
FAQ’s
How many km is a half marathon?
How many km is a half marathon equals 21.0975 km, often rounded to 21.1 km for simplicity.
How many miles is a half marathon?
It is 13.109 miles, usually written as 13.1 miles on signs and medals.
Why is half marathon in km not a clean 21?
Because the half is exactly half of 42.195 km. That official marathon length creates 21.0975 km.
How many km in half marathon for training routes?
Use 21.1 km as your planning number. It stays close to the exact distance while keeping calculations easy.
How far is a marathon and half marathon together?
42.195 km for the full and 21.0975 km for the half. Side by side, the marathon is double the half.
Should I set my watch to km or miles?
Choose the unit that matches course markers. If the race is marked every kilometre, set km so how many km is a half marathon converts directly into clean splits.
Conclusion
You asked how many km is a half marathon. Remember 21.0975 km (21.1 km) or 13.109 miles (13.1 miles). Build even splits, practise fueling, and keep your training consistent. Whether you search how many km in half marathon, convert for friends asking how many miles is a half marathon, or compare how far is a marathon and half marathon is, the numbers are now clear. Save this guide on smartcric, set your watch to half marathon in km, and enjoy every step to the finish line.
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