The short answer
A first half marathon is a sensible next goal when you can repeat three running or run-walk sessions most weeks, recover from a 45–60 minute easy outing, and protect time for a gradually longer session. If that baseline is not stable, build toward a 5K or 10K first rather than compressing half-marathon preparation.
Readiness is not a qualifying pace. It is the ability to repeat the training process without every long run becoming a rescue mission.
The readiness screen
Answer each item with yes, not “probably on a perfect week.”
- I have completed at least several weeks of consistent easy running or run-walking.
- I can schedule three sessions in an ordinary week.
- One weekly window can gradually grow beyond an hour.
- Easy effort is genuinely conversational.
- I can reduce a bad week without trying to make up every missed kilometre.
- Current pain does not change my gait.
- The event cutoff, terrain, and travel fit the way I expect to complete it.
If several answers are no, choose a 10K block first. That is a timeline decision, not a verdict on whether you are “a real runner.”
Choose the plan length from the constraint
| Situation | More realistic choice |
|---|---|
| New to running or returning after a long break | Build a 5K/10K base, then use a longer half-marathon plan |
| Three stable weekly runs and a comfortable 45–60 minute easy session | A 16–20 week half-marathon plan |
| Recent consistent 10K training and four available windows | A shorter plan may fit, but it should not require a sudden load jump |
| Repeated pain, illness, or severe fatigue | Pause the timeline and get appropriate guidance |
Running-injury research does not provide one universally safe weekly progression. A systematic review found conflicting evidence for specific distance, duration, frequency, and intensity parameters. That is why a plan should respond to the runner, not hide behind a fixed percentage.
What the week needs to contain
1. Easy running
Most running should feel controlled enough to talk in sentences. Easy days build frequency and leave room to absorb the longer and more specific work.
2. A gradually longer session
The long run develops time on feet, confidence, clothing and shoe decisions, and fueling practice. It does not need to reach 21.1K before race day in every plan. Its useful length depends on training history, pace, recovery, total weekly load, and available weeks.
3. One controlled quality stimulus
This might be short hills, a steady block, or planned intervals. It should have a clear job. If every run becomes moderately hard, recovery becomes ambiguous and the long session often suffers.
4. Strength and recovery
Use simple lower-body, calf, hip, and trunk work. Keep hard strength away from the most demanding run when possible, and reduce it before key long sessions if soreness changes mechanics.
A four-week example inside the plan
This is a pattern, not a distance prescription.
- Week A: normal easy frequency + long run.
- Week B: repeat frequency; extend one useful variable.
- Week C: consolidate with another small progression if recovery is stable.
- Week D: reduce volume while keeping the habit and some normal rhythm.
Do not progress the long run, add a new speed session, increase strength volume, and remove recovery in the same week.
Start fueling practice before race week
Longer outings are where you learn what breakfast, fluids, and carbohydrate sources are comfortable. Use the marathon fueling planner to organize a practice schedule, but test it during training and individualize it. A calculator cannot know your tolerance, weather, medical needs, or what the event supplies.
Decide what happens after a missed week
- Resume with the next safe priority.
- Shorten the next long run if the gap changes readiness.
- Do not combine two long runs or two hard sessions to “catch up.”
- Move the goal date when the remaining calendar no longer supports gradual preparation.
The finish line should create structure, not force you to deny the evidence in front of you.
Choose the next path
Use the training start-date calculator to count backward from the event. If the readiness screen is not stable, use the 10-week 10K plan. If it is, compare the 16-week half-marathon plan with your actual weekly windows.
26weeks can create a goal-specific plan and adapt near-term decisions when recovery, completed training, stress, schedule, or a missed workout changes the week. It cannot guarantee a finish or replace individualized medical care.
Professional-care boundary
Seek appropriate clinical guidance for pain that changes gait, persistent or worsening symptoms, chest discomfort, fainting, severe shortness of breath, a recent procedure, pregnancy-related considerations, or a condition that affects exercise safety.