distance

Half Marathon Pace Calculator

Calculate your half marathon pace, finish time, and split times. Get VDOT training zones, race predictions, and negative-split strategy for your 13.1 mile race.

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Sub-4 Marathon

Target a sub-4-hour marathon finish with even splits

Key values: 42.195 km · 5:41/km pace · 3:59:59

First Marathon

Comfortable pace for a first-time marathon finisher

Key values: 42.195 km · 6:30/km pace · ~4:34

10K Race Pace

Calculate pace for a target 10K finish time of 50 minutes

Key values: 10 km · 50:00 target · Pace-based

Documentation

Half Marathon Distance

A half marathon is exactly 21.0975 km (13.1094 miles). Pace is typically expressed as minutes per kilometer (or mile):

\text{Pace} = \frac{\text{Total time (min)}}{21.0975}

\text{Finish time} = \text{Pace (min/km)} \times 21.0975

Common Pace Targets

Finish time	Pace (min/km)	Pace (min/mi)	Level
1:30	4:16	6:52	Elite/sub-elite
1:45	4:58	8:00	Advanced
2:00	5:41	9:09	Intermediate
2:15	6:24	10:18	Recreational
2:30	7:06	11:26	Beginner
3:00	8:32	13:44	Walk/run

Predicting from Shorter Races

Riegel's formula estimates race time at a new distance using a known performance:

T_2 = T_1 \times \left(\frac{D_2}{D_1}\right)^{1.06}

Example: A 10K in 50:00 predicts a half marathon of approximately $50 \times (21.1/10)^{1.06} \approx 1\text{:}51\text{:}14$ . The exponent 1.06 accounts for the fact that pace slows at longer distances.

Pacing Strategy

Even splits: Run every kilometer at the same pace. The simplest and most reliable strategy for first-timers.
Negative splits: Run the second half faster than the first. Start 10–15 sec/km slower, then pick up. Most sub-elite PRs use this strategy.
Avoid positive splits: Starting too fast leads to a dramatic slowdown (“hitting the wall”) after km 15–18.

Race-day rule: The first 5 km should feel easy. If you're breathing hard at km 3, you started too fast.

Frequently Asked Questions

How long does it take to run a half marathon?

The average half marathon finish time is about 2 hours for men and 2 hours 15 minutes for women. Beginners typically finish in 2:15 to 2:45, while advanced runners target sub-1:45. Elite runners finish under 1:05 (men) or 1:10 (women).

What pace do I need for a sub-2-hour half marathon?

To finish under 2 hours, you need an average pace of 5:41 per km (9:09 per mile) or faster. Building in a small buffer, aim for 5:35 per km to account for hills, crowds, and hydration stops.

How do I predict my half marathon time from a 10K?

Multiply your 10K time by 2.22 using a simple multiplier, or use the Riegel formula: $T_2 = T_1 \times (D_2/D_1)^{1.06}$ . A 50-minute 10K predicts roughly 1:51 for the half marathon, assuming equivalent training.

Should I run even splits or negative splits in a half marathon?

Negative splits (running the second half faster) generally produce the best results. Start 10 to 15 seconds per km slower than target pace for the first 5 km, settle into pace through km 15, then pick up if you feel strong. Going out too fast often leads to a dramatic slowdown after km 16.

How many weeks of training do I need for a half marathon?

Most half marathon training plans run 10 to 14 weeks. Beginners should have a running base of at least 15 to 20 km per week before starting a plan. Key workouts include a weekly long run building to 18 to 20 km, a tempo run, and easy recovery runs.

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