How to Run a Sub 1 Hour 20
Half Marathon.

Pace, splits & training plan for a sub 1:20 half marathon.

What pace is a 1:20 half marathon?

A 1:20 half marathon is a pace of 3:48 per kilometre (6:06 per mile), or 15.8 km/h (9.8 mph).

Pace /km

3:48

min/km

Pace /mile

6:06

min/mi

Speed

15.8

km/h

Speed

9.8

mph

1:20 Half Marathon splits.

KM Cumulative Time
1 3:48
2 7:35
3 11:23
4 15:10
5 18:58
6 22:45
7 26:33
8 30:20
9 34:08
10 37:55
11 41:43
12 45:30
13 49:18
14 53:05
15 56:53
16 1:00:40
17 1:04:28
18 1:08:15
19 1:12:03
20 1:15:50
21 1:19:38
21.0975 1:20:00
Mile Cumulative Time
1 6:06
2 12:12
3 18:18
4 24:25
5 30:31
6 36:37
7 42:43
8 48:49
9 54:55
10 1:01:01
11 1:07:08
12 1:13:14
13 1:19:20
13.11 1:20:00

Get the 12-week plan on Garmin or Coros.

Race, tempo and interval paces from the matching 1:20 half marathon training plan, plus two real weeks already on it.

Race

3:47

min/km

Tempo

3:29–3:59

min/km

Intervals

3:04–3:26

min/km

Week 3 59.7 km 16 km long run 6 runs
Monday

Easy 5km

4:47 - 5:17 / km

Tuesday

Intervals

3:29 - 3:46 / km

Wednesday

Easy 11km

4:47 - 5:17 / km

Thursday

Tempo

3:56 - 4:26 / km

Friday

Rest

Saturday

Tempo

3:56 - 4:26 / km

Sunday

Long Run 16km

5:02 - 5:41 / km

Week 10 62.5 km 24 km long run 5 runs
Monday

Rest

Tuesday

Intervals

3:29 - 3:46 / km

Wednesday

Easy 13km

4:47 - 5:17 / km

Thursday

Progression

3:56 - 4:26 / km

Friday

Rest

Saturday

Easy 5km

4:47 - 5:17 / km

Sunday

Progression

5:02 - 5:41 / km

Start the 1:20 half marathon training plan

What does this pace feel like?

A 3:48/km average for the half marathon is a serious, advanced effort — quick enough that breathing is deep and rhythmic from the early kilometres and conversation is out of the question. The pace sits close to threshold, so the race rewards runners who have trained their body to clear lactate efficiently and who have the discipline to hold back through a fast first 10 km.

Adjust your target.

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Get Your Free Half Marathon Training Plan

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Related.

Aiming faster?

Sub 1:15 Half Marathon Pace Guide

Training plans

Half Marathon Running Plans

Need more time?

Sub 1:30 Half Marathon Pace Guide
Back to Pace Calculator

FAQs.

Is a 1:20 half marathon good?

Yes — sub-1:20 requires 3:48/km (6:06/mi) for the full distance and is a benchmark that places you well inside the top few percent at most big-city half marathons.

What 10K time predicts a 1:20 half marathon?

Around 36:00–36:30. If your 10K is faster but the half keeps escaping you, the missing ingredient is usually weekly volume rather than speed.

How many weeks do I need to train for a 1:20 half?

From a 1:23–1:25 base, 12 weeks of structured threshold work and pace-specific long runs is a realistic timeline. From further back, allow a full season.