Sub-1:45 half marathon training plan

To run a half marathon under 1:45:00 you need to average 4:59 per kilometre. That takes a fitness of about VDOT 42.6 — the same athlete who can run a 5 km in 22:50, a 10 km in 47:22, a marathon in 3:37:50. From a starting point about 5% slower, a focused 14-week block is a realistic way to get there; from much further back it takes more than one build, and the table below says how many weeks.

Build my sub-1:45 half marathon plan — free

Set from your own time trial. The first week is yours to train on before you decide.

The pace, and the splits

Goal	1:45:00 for the half marathon
Average pace	4:59 per km
At 5 km	24:53
At 10 km	49:46
At 15 km	1:14:39

What that fitness looks like at other distances

A goal time is really a fitness level. At VDOT 42.6, Jack Daniels' model predicts:

5 km	22:50
10 km	47:22
Marathon	3:37:50

If you can already run close to these at a shorter distance, the fitness is there and the goal is about endurance and pacing. If you cannot, the goal is about fitness first.

How long it takes from where you are

Your half marathon today	Realistic time to the goal
1:48:09 — 3% short	About 8 weeks of consistent training
1:51:18 — 6% short	About 15 weeks of consistent training
1:55:30 — 10% short	About 23 weeks of consistent training
2:01:48 — 16% short	More than one training block. Build to an interim goal first.

Based on roughly 0.4% improvement a week for a trained runner, capped at about 12% for a single block — the same rule the plan uses when it tells you whether your own goal is realistic.

Training paces at this fitness

Easy — a ceiling, not a target	5:49/km or slower
Marathon pace	5:13/km
Threshold	4:56/km
Interval (VO₂max)	4:27/km
Repetition	4:10/km

These are the paces of the goal, which you train toward. A plan built from your own time trial starts from where you are now and moves them as you get fitter.

A 15-week block toward it

Generated for a runner currently doing 1:50:15 for the half marathon, on about 51 km a week. Volume rises no more than 10% a week and every fourth week comes down.

Week	Phase	Volume	Load
1	Base	51 km	279
2	Base	53 km	291
3	Base	55 km	298
4	Base · down	38 km	215
5	Base	56 km	306
6	Base	57 km	306
7	Build	55 km	327
8	Build · down	42 km	242
9	Build	55 km	329
10	Build	57 km	335
11	Build	58 km	344
12	Peak · down	46 km	262
13	Peak	60 km	348
14	Taper	42 km	235
15	Race · race	26 km	206

What the plan says about this goal

Your goal is 5% faster than today's fitness. Over 15 weeks that is a realistic ask if the plan gets done. It is not a certainty — nothing here is — but it is the right side of possible.

Common questions

What pace do I need for a sub-1:45 half marathon?

4:59 per kilometre, held evenly. Going through halfway more than a few seconds a kilometre quicker than that is the commonest way a goal race is lost, because the cost of going out fast is paid back with interest in the second half.

How many weeks does it take to train for a sub-1:45 half marathon?

It depends entirely on how far away you are now. A trained runner improves roughly 0.4% a week in a good block, and one block of training is worth about 12% at most. So from 3% short it is about 8 weeks; from 10% short it is closer to 23; beyond 12% it is more than one season's work.

What should my easy runs be at this fitness?

No faster than 5:49 per kilometre, and slower is fine. Most runners chasing a time goal run their easy days too fast, which leaves them too tired to hit the sessions that actually build speed.

Is this plan right for me?

The numbers on this page are worked out for a runner currently doing 1:50:15 for the half marathon, on about 51 km a week. Yours will differ. Building your own plan asks for a recent race or time trial and sets every pace from it, adjusted for the altitude you train at.

Other half marathon goals

Half marathon races in South Africa

Worth reading

Build my plan