Disclaimer: The information in this article is general in nature and is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your doctor or other qualified health professional before starting any exercise programme or with any questions you may have regarding a medical condition.
A new runner can usually get to 5 km in about nine weeks. A first marathon can take 12 to 16 weeks if you already run, or about six months if you are starting from very little exercise. The 10 km and half marathon sit in between. For those, the best way to set a timeframe is to count forward from the distance you run now.
Below, you'll find where those figures come from, how to work out your own number for the middle distances, and what to do if your race is sooner than that.
Training time by race distance
This table covers training to finish a race comfortably, not to chase a fast time.
| Distance | Starting from little or no running | Already running regularly |
|---|---|---|
| 5 km | About 9 weeks on a run-walk plan | You may be ready now if you can run for 30 minutes |
| 10 km | Finish a 5 km plan first, then build up | Count forward from your weekly distance |
| Half marathon (21.1 km) | Finish a 5 km plan first, then build up | Count forward from your weekly distance |
| Marathon (42.2 km) | About six months | 12 to 16 weeks |
At the time of writing (November 2026), we couldn't find an Australian health or sport authority that sets a standard number of weeks for a 10 km or half marathon. That is why those rows ask you to count forward instead.
Starting from no running: aim for 5 km first
If you don't run at all yet, 5 km is the sensible first target, even if a longer race is your real goal. The UK's free NHS Couch to 5K programme takes you to 5 km in nine weeks. You run three times a week, with rest days in between.
The first week starts with 1-minute runs, each followed by a 90-second walk. Each week you run a little more. The programme says you can take longer than nine weeks if you want to go at your own pace, so repeating a week is fine.
The end point is useful for planning the next step. By the end of Couch to 5K, you are running for about 30 minutes without stopping. If you can already do that, you are past the beginner stage for a 5 km and can look at a race date now.
Our first 5 km guide covers the week-by-week run-walk approach in more detail, including how to pick an event with enough training time. A free Saturday parkrun is also a low-pressure way to try the 5 km distance before you enter a paid race.
How to work out your time for a 10 km or half marathon
For these two distances, your timeframe depends mostly on how far you already run each week. A simple rule from Australia's health information service helps you count it. Healthdirect advises that you increase distance by no more than 10% per week.
That rule sets the pace of your build-up. To use it, you need two numbers:
- the total distance you run in a normal week now
- the total distance your chosen training plan asks for in its biggest week
You can find the second number in a training plan from a running coach, club or race organiser. Then count how many weeks it takes to get from one to the other at 10% a week or less.
A worked example
This example is an illustration of the counting method, not a training plan. Say you finish Couch to 5K and run about 15 km a week. If you add 10% each week, your weekly totals look roughly like this:
- Week 1: 15 km
- Week 4: 20 km
- Week 7: 26.6 km
- Week 10: 35.4 km
So a plan that peaks at about 20 km a week would take you around a month of build-up. A plan that peaks at about 35 km a week would take around ten weeks.
Add easier weeks
Most people can't add distance every single week. An ABC Everyday piece on marathon training describes a typical training month. It has three weeks of intense training, then one less intense week so the body can adapt. Exercise physiologist Kirra Rankin suggests cutting your distance by about 20% in the easier week.
If you use the same pattern for a 10 km or half marathon, add one extra week for every three weeks of build-up. In the example above, the ten-week build becomes about thirteen weeks. Then add a little spare time for a cold, a busy fortnight at work or a sore calf.
What a typical training week looks like
Whichever distance you pick, a simple week has three runs with a rest or cross-training day between each one. Make two of them shorter, easy runs. Make the third your longer run, and let that one grow as race day gets closer.
Easy means a pace you could hold a conversation at. Most of your training should feel comfortable, and the longer run should be slower than your shorter runs, not faster. Healthdirect also recommends that you warm up and cool down before and after each run to reduce your risk of injury, starting with gentle movements.
If you have time for a fourth session, a short strength workout is often a better use of it than another run.
Marathon preparation for first-timers
The marathon is the other distance where we found clear expert timeframes. The same ABC Everyday article says a 12 to 16-week programme may work for people with some running experience. People who are inactive may need much longer. For someone starting from the couch, Rankin suggests a good six months to prepare, enjoy the process and avoid injury.
Rankin's starting point for beginners is about three days of running a week, up to about 15 km in the first week. She suggests adding about 2 km a week from there. From a 15 km week, that first step is a little more than the 10% rule above, so if you are new to running or prone to niggles, the smaller increase is the safer choice. Around two weeks before the race, she suggests one run of about 30 km. That run gives you confidence that you can reach the finish line.
Sports scientist Dr Kellie Pritchard-Peschek told the ABC that people should check with a GP before they start training for a marathon. She said the aim is medical clearance that you are fit and healthy enough to train. If you work with an exercise professional, they can also do an exercise screening.
Rankin also says strength training is a key part of a marathon programme. The article adds that rest days between runs help the body recover and avoid injuries.
What can make your preparation longer
These factors can move your own timeframe.
Your current fitness and other sport
Rankin says the length of a training programme can vary with a person's strength and athleticism. Whether you play other sports can change how many kilometres you can manage each week.
Injury or a health condition
Healthdirect says that if you are recovering from an injury or illness, you may need to change your running programme to suit your body. That may mean a slower build-up, so allow extra weeks. If you have an illness or injury, Healthdirect advises seeing a doctor before you begin.
Your age
Healthdirect states that beginners of any age can start running. It also suggests a check-up with your doctor first if you are new to running and aged over 40. The same applies if you have a chronic medical condition, are pregnant, or are recovering from an injury or illness.
Finishing or chasing a time
The timeframes in this guide are for getting to the finish line. If you want a particular finishing time, you will be adding faster sessions on top of the distance work. A running coach can help you plan that safely, and it is reasonable to allow more time than the figures above.
Rest between runs
Healthdirect suggests resting your body for 24 to 48 hours between runs. Squeezing in extra runs to finish sooner cuts into that recovery time.
What if your race is sooner than your timeframe?
If you have already entered and the weeks don't add up, don't try to catch up by adding distance quickly. Jumping well past the 10% guide raises your injury risk. Better options:
- Check whether the event also has a shorter distance, and ask the organiser if you can switch.
- Ask whether your entry can be transferred to a later event or the following year.
- If walking is allowed and the cut-off is generous, plan a run-walk race and aim simply to finish.
Signs you need more time
A plan is a guide, not a contract. It is worth adding a week or two, or repeating a week, if:
- your longer run leaves you sore for several days
- you have a pain that changes the way you run, or keeps coming back in the same spot
- you have missed two or more weeks through illness, travel or work
- every run feels hard, even the easy ones
Pain that doesn't settle with rest is worth checking with a GP or physiotherapist before you keep training.
Choosing a race date that fits your timeframe
Once you have your number of weeks, count forward from today and add two to four spare weeks. Then look for a race on or after that date. You can browse upcoming 5 km events, 10 km events, half marathons and marathons on KeepActive. You can also narrow a search to your city, for example half marathons in Sydney, Melbourne or Brisbane.
Before you enter, check the organiser's page for the cut-off time, whether walking is allowed and the course profile. A hilly course or a tight cut-off may be a reason to choose a later race or a shorter distance first.
Training with others can make a long build-up easier to stick with. You can find running groups near you and compare their pace, meeting day and distance. Our article on run clubs explains what to expect at a first session.
