Free Tool

Half Marathon Pace Calculator

Enter your goal finish time and instantly get your target pace per km or mile, even-split checkpoints at 5K, 10K, 15K, and 20K, plus the training paces your plan should include.

Goal Finish Time
Target Pace
5:41
min/km
Per mile
9:09
min/mile
Even-Split Checkpoint Times
5 km
0:28:26
10 km
0:56:53
15 km
1:25:19
20 km
1:53:45
Finish
2:00:00
Training Pace Zones (per km)
Easy / Recovery
6:50
+20% of HMP
Long Run
6:32
+15% of HMP
Half Marathon Pace
5:41
Race pace
Tempo
5:17
-7% of HMP

How to Use This Half Marathon Pace Calculator

Enter your goal finish time in hours, minutes, and seconds. The calculator instantly shows your required average pace per kilometre or mile. Below that, you'll see even-split checkpoint times — the exact clock times you should see at 5 km, 10 km, 15 km, and 20 km if you run perfectly even splits.

The training pace zones are calculated relative to your goal half marathon pace (HMP): easy runs at HMP +20%, long runs at HMP +15%, and tempo runs at HMP −7%.

What Is Half Marathon Pace?

Half marathon pace (HMP) is the average speed required to cover 21.0975 km (13.1 miles) in your goal time. It sits between your 10K race pace (faster) and marathon pace (slower) in the effort spectrum.

For reference: a 2-hour half marathon requires 5:41 per km (9:09 per mile). A 1:45 half marathon demands 4:59 per km (8:00 per mile). A sub-1:30 requires 4:15 per km (6:51 per mile).

Even Splits vs. Negative Splits

The calculator shows even-split times, but negative splits are optimal in practice. Running the second half slightly faster than the first is both faster on average and feels better psychologically.

A practical approach for most runners: run the first 5 km 5–10 seconds per km slower than goal HMP, settle into target pace from km 5–15, then push in the final 6 km if you still feel strong. The goal is to cross the finish with energy remaining — not to collapse at the line.

Half Marathon Pacing Mistakes

  1. Going out too fast. The first 5 km of a half marathon feels deceptively easy. Running 15–20 seconds per km faster than goal pace in the opening km leads to a painful final 5 km.
  2. Skipping fuelling. At half marathon distances, a gel at km 8–10 can make a meaningful difference for runners who take longer than 90 minutes.
  3. Ignoring training pace zones. Running long runs at race pace, or running easy days too hard, are the most common mistakes in half marathon training. Use the zones above to keep your training structured.

Training Paces for Half Marathon

The three most important paces in a half marathon training plan:

Frequently Asked Questions

Half marathon pace is the average speed you need to maintain across 21.0975 km (13.1 miles) to achieve your goal finish time. For example, a 2-hour half marathon requires an average pace of 5:41 per km (9:09 per mile). Your half marathon pace is typically 10–20 seconds per km faster than your marathon pace and 30–45 seconds per km slower than your 10K pace.
Negative splits — running the second half slightly faster than the first — are optimal for most runners. Aim to run the first 5 km at 5–10 seconds per km slower than your goal half marathon pace, then settle into target pace from km 5–15, and push in the final 6 km if you have energy remaining. Even splits are fine; avoid positive splits (going out too fast) as glycogen depletion can still be a factor in the final 5 km.
This calculator gives you the theoretical even-split pace for your goal time. Actual race performance depends on course elevation, weather, pre-race fatigue, and pacing discipline on the day. Use this as your target and adjust by 5–10 seconds per km based on conditions.
Long runs for half marathon training should be 60–90 seconds per km slower than your goal half marathon pace. If your goal pace is 5:30/km, run your long runs at 6:30–7:00/km. This builds the aerobic base needed to sustain your pace across 21 km without excessive recovery cost.
As a rough guide using the Riegel formula: your half marathon pace will be approximately 6% slower than your 10K pace and about 12% slower than your 5K pace. If you run 10K at 5:00/km, expect your half marathon pace to be around 5:18/km. PacecraftAI uses your recent race times to project your accurate half marathon pace target.

Want a personalised half marathon training plan?

PacecraftAI builds an adaptive 10–16 week half marathon plan around your goal time, adjusts it every week, and coaches you 24/7 — including race-day pacing strategy.

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