Who this plan is for
You've signed up for your first Half Ironman. It's 12 weeks out. You can run for 30 minutes without walking, you can ride a bike for an hour or two on a Saturday morning, and you can swim a few lengths of a 25m pool without gasping at the wall. You have never raced a triathlon before, or maybe you've done a sprint. You are not a swimmer. You're not really a cyclist either. You are an adult with a job and a life and you want to finish a 70.3 without blowing up, getting injured, or losing your weekends for three months.
This plan is written for that person. 12 structured weeks, aimed at a first 70.3 finish somewhere in the 6:00-7:30 range. It won't get you a Kona slot. It won't work if you're starting from zero (scroll down to the base camp section if that's you). And it doesn't need a power meter, a coach, or an expensive wetsuit to execute.
I'm an age grouper, not a coach. This is what worked for me and for people around me on the way to their first half. Treat it as a starting shape, not a contract — move sessions around to fit your life, and cut volume before you cut sleep.
The 70.3 distance — what you're training for
A Half Ironman — branded as "70.3" because the total distance is 70.3 miles (113.1 km) — consists of:
- 1.9 km swim (1.2 miles) — usually open water, almost always wetsuit-legal in European races
- 90 km bike (56 miles) — varies from flat coastal loops to 1,500m+ climbing mountain courses
- 21.1 km run (13.1 miles, a half marathon) — off the bike, so expect heavy legs
Realistic finish times for a first-time 70.3 athlete following a plan like this one land between 6:00 and 7:30. Breakdown:
- Swim: 35-50 minutes
- T1 (swim-to-bike transition): 4-6 minutes
- Bike: 3:00-3:45
- T2 (bike-to-run transition): 2-4 minutes
- Run: 2:00-2:45
Training volume to get there: 8-12 hours per week on average across the 12-week block, peaking at 12-14 hours in the two hardest weeks. That's it. You don't need 20 hours a week to finish your first 70.3. You need consistency and a plan.
For the wider context — distances, formats, where 70.3 fits in triathlon — see the Triathlon Training Hub.
Before week 1: the baseline check
Be honest with yourself. Four questions:
- Can you swim 400m non-stop (16 lengths of a 25m pool), even slowly, without holding the wall?
- Can you ride a bike for 2 hours at conversational pace without bonking?
- Can you run 8 km continuously, even slowly?
- Do you have at least 7-8 hours per week to commit to training, consistently, for 12 weeks?
If you answered yes to all four, you're ready for Week 1. If you answered no to any of the first three, you need a 4-week base camp before the plan starts.
Base camp (4 weeks): 3 swims per week (start at 10 minutes, build to 25 minutes of continuous-ish swimming), 3 bike rides per week (start at 45 minutes, build one to 2 hours), 3 runs per week (start at 20 minutes, build one to 8 km). No intensity. Just aerobic work, zone 2, slow and steady. At the end of the 4 weeks, retest. Then start Week 1.
The 12-week plan — week by week
This is the actual plan. Read the weekly structure section below first so you know how the sessions fit into the days. All intensities refer to the zones explained further down.
Notation: WU = warm-up, CD = cool-down, Z1-Z5 = intensity zones, T-pace = threshold pace (roughly the fastest pace you can hold for 60 minutes).
Phase 1 — Build base (Weeks 1-4, 7-9 h/week)
| Wk | Hours | Swim | Bike | Run | Brick / Long | Notes |
|---|---|---|---|---|---|---|
| 1 | 7h | 2x: 300 WU + 6x100 easy + 200 CD | Tue 45 min Z2 · Wed 60 min Z2 | Tue 30 min Z2 · Thu 40 min Z2 | Sat: 2h bike Z2 + 15 min run off | All easy. Focus on consistency. |
| 2 | 8h | 3x: 400 WU + 8x100 easy + 200 CD | Wed 75 min Z2 | Tue 35 min · Thu 45 min Z2 | Sat: 2h15 bike Z2 + 20 min run · Sun 60 min run | Add 3rd swim this week. |
| 3 | 9h | 3x: 400 WU + 10x100 moderate + 200 CD | Wed 90 min Z2 | Tue 40 min · Thu 50 min Z2 with 4x30s strides | Sat: 2h30 bike Z2 + 25 min run · Sun 75 min run | First "real" volume week. |
| 4 | 6h | 2x: easy 30 min technique | Wed 60 min Z2 | Tue 30 min · Thu 40 min Z2 | Sat: 90 min bike Z2 + 15 min run · Sun 45 min run | Recovery week. Don't skip it. |
Phase 2 — Build intensity (Weeks 5-8, 9-12 h/week)
| Wk | Hours | Swim | Bike | Run | Brick / Long | Notes |
|---|---|---|---|---|---|---|
| 5 | 10h | 3x: 400 WU + 6x150 @ T-pace + 200 CD | Wed 90 min w/ 3x8 min Z3 · Fri 45 min Z2 | Tue 45 min Z2 · Thu 55 min w/ 4x3 min Z3 | Sat: 3h bike Z2 w/ 2x15 min Z3 + 25 min run · Sun 90 min run | First threshold work. Ease in. |
| 6 | 11h | 3x: 400 WU + 8x150 @ T-pace + 200 CD | Wed 2h w/ 3x10 min Z3 · Fri 45 min Z2 | Tue 50 min · Thu 60 min w/ 5x3 min Z3 | Sat: 3h15 bike w/ 2x20 min Z3 + 30 min run · Sun 105 min run | Race a sprint triathlon this weekend if available. |
| 7 | 12h | 3x: 400 WU + 10x150 @ T-pace + 200 CD | Wed 2h w/ 4x10 min Z3 · Fri 60 min Z2 | Tue 55 min · Thu 70 min w/ 6x3 min Z3 | Sat: 3h30 bike w/ 3x15 min Z3 + 35 min run · Sun 2h run | Biggest week so far. Sleep 8+ hours. |
| 8 | 8h | 2x: 1 km continuous moderate | Wed 75 min Z2 | Tue 40 min · Thu 45 min Z2 | Sat: Olympic-distance B-race OR 2h bike Z2 + 30 min run | Recovery/test week. Race Olympic if possible. |
Phase 3 — Peak (Weeks 9-10, 12-14 h/week)
| Wk | Hours | Swim | Bike | Run | Brick / Long | Notes |
|---|---|---|---|---|---|---|
| 9 | 13h | 3x: 400 WU + 4x400 @ T-pace + 200 CD | Wed 2h15 w/ 4x12 min Z3 · Fri 75 min Z2 | Tue 60 min · Thu 75 min w/ 4x5 min Z3 | Sat: 4h bike (full 90km+) w/ 3x20 min Z3 + 30 min run off · Sun 2h15 run | Peak volume. This is the top. |
| 10 | 14h | 3x: full 1.9 km open water swim rehearsal | Wed 2h30 Z2/Z3 mix · Fri 75 min Z2 | Tue 60 min · Thu 75 min w/ 5x4 min Z3 | Sat: 4h15 bike (race-distance+) + 40 min run off (dress rehearsal) · Sun 2h15 run | Nutrition dress rehearsal on Saturday. Full race kit. |
Phase 4 — Taper (Week 11, ~9 h/week)
| Wk | Hours | Swim | Bike | Run | Brick / Long | Notes |
|---|---|---|---|---|---|---|
| 11 | 9h | 3x: 400 WU + 6x100 moderate + 200 CD | Wed 90 min Z2 w/ 2x10 min Z3 · Fri 60 min Z2 | Tue 45 min · Thu 50 min w/ 4x2 min Z3 | Sat: 2h30 bike Z2 + 20 min run · Sun 90 min run | Volume down, intensity maintained. Don't add sessions. |
Phase 5 — Race week (Week 12, 4-5 h/week)
| Day | Session | Notes |
|---|---|---|
| Mon | Rest or 30 min easy walk | Sleep priority. Start hydrating. |
| Tue | 45 min bike Z2 + 15 min run off, both easy | Spin the legs. Don't push. |
| Wed | 30 min swim: 200 WU + 4x100 moderate + 200 CD | Feel for the water. That's it. |
| Thu | Rest or 20 min easy run + 4x20s strides | Travel day if racing away. |
| Fri | 20 min bike easy + 10 min run easy + 10 min swim in race venue if possible | Race pack-up, gear check, bike drop. |
| Sat | 20 min easy activation (walk, spin, or short swim) | Early dinner. Lay out kit. Sleep. |
| Sun | Race day. | Execute. |
Weekly structure overview
A typical training week looks like this:
- Mon — Rest. Full day off. No training. This is when adaptation happens.
- Tue — Swim + Run. Morning swim, evening run. Or both back-to-back if you're short on time.
- Wed — Bike. The midweek quality bike session. Intervals if the plan calls for them.
- Thu — Swim + Run. Second swim and a run with some intensity.
- Fri — Rest or mobility. Optional easy spin if you're feeling fresh. Do not add quality here.
- Sat — Long bike + brick run. The most important session of the week. Long aerobic bike with the occasional tempo block, finished with a short run off the bike.
- Sun — Long run. Z2 aerobic, no intensity, just time on feet.
Why this structure: the two big sessions (Saturday brick, Sunday long run) are back-to-back on purpose. That simulates race-day fatigue and is the single most effective pattern for 70.3 prep. Monday rest is non-negotiable — people who train 7 days a week hit Week 8 injured or burnt out. Friday rest protects Saturday.
Training intensity zones, briefly
You don't need a power meter or a lab test for a first 70.3. You need to understand five rough zones and train mostly in two of them.
- Z1 — Recovery. You could hold a full conversation. Walking, spinning, very easy jogging.
- Z2 — Endurance. You can speak in full sentences but you wouldn't want to give a speech. This is 70-80% of your training. It should feel "almost too easy."
- Z3 — Tempo. Short sentences. You can talk but it's work. This is your 70.3 race pace on the bike.
- Z4 — Threshold. One word at a time. Hard. Uncomfortable. You can hold this for ~40-60 minutes if you have to.
- Z5 — VO2 max. Can't talk. Gasping. Short intervals only.
This plan uses Z2 and Z3 almost exclusively. Z4 shows up rarely as threshold pace in the swim. Z5 does not appear — it's not useful for 70.3 prep at the beginner level, and it increases injury risk disproportionately.
Rough heart rate anchors, if you use a monitor: Z2 is approximately 65-75% of max HR, Z3 is around 76-85%, Z4 is 86-92%. These are broad ranges — individual variation is huge, so treat them as a starting point, not gospel.
Nutrition during training and race day
Under-fueling is the single most common reason first-timers blow up during a 70.3. The bike is where you eat. The run is where the bike nutrition pays off or punishes you.
Key numbers to practice:
- Carbs per hour on the bike: 60-90 grams/hour. Lower end if your stomach is sensitive, higher end if you've trained your gut. Start at 60 g/h and build up across the 12 weeks.
- Hydration: roughly 500-750 ml/hour on the bike, more in heat. Drink to thirst + a bit more, not on a strict schedule.
- Sodium: salty sweaters need 500-1000 mg/hour, average sweaters 300-600 mg/hour. If you finish long rides with salt crust on your kit, you're on the higher end.
- Caffeine: a small dose (50-100 mg) in the last hour of the bike or early run can help. Don't try it for the first time on race day.
Practice protocol: every Saturday long bike from Week 5 onwards, eat and drink exactly what you plan to use on race day. Same carbs, same bottles, same gels or chews or whatever works for your stomach. By Week 10 your nutrition should be boring and automatic. I'm not recommending specific brands — what works for me may destroy your stomach. Test in training, not on race day.
On the run, most people can take an additional 30-60 g/hour of carbs, usually via gels and aid-station cola. Expect your stomach to be less cooperative on the run than on the bike.
Minimum viable gear kit
You don't need premium gear for a first 70.3. You need the right gear. In rough priority order:
- Wetsuit. The single most important purchase for a beginner. A wetsuit adds 5-10% swim speed and, more importantly, buoyancy — which dramatically reduces panic in open water. Budget tier works fine for a first 70.3. Rent one if you're only doing one race.
- Tri suit (one-piece or two-piece). You wear it for all three disciplines. It has a thin chamois pad that's swim-friendly. A cheap one is fine.
- Bike. Whatever you already ride is fine. Road bike with clip-on aero bars beats a TT bike you can't handle. A well-fitted road bike beats a poorly-fitted tri bike every day of the week. Budget or premium — your fit matters more than your frame.
- Helmet. Any road helmet that fits. An aero helmet saves a few minutes but isn't required for a first 70.3.
- Shoes. Running shoes you've trained in. Not new ones. Not new ones on race day. Never new ones on race day.
- Goggles. Two pairs: clear lens (for overcast or early starts) and tinted (for sun). Bring both to the race venue.
- Nutrition storage. Bento box or frame bag on the bike for gels and solid food, plus two bottle cages. A between-the-arms rear hydration system is nice but optional.
Race day pacing strategy
The single biggest race-day mistake is going out too hard on the bike. The single biggest reward is pacing the bike conservatively so you can run.
- Swim — conservative. Start at 70% effort. Let faster swimmers go. Settle into a rhythm you could hold for 2 km even if the race were longer. The swim is 35-50 minutes out of a 6-7 hour day. Saving one minute in the swim by going hard costs you 10 minutes later.
- Bike — capped effort. For a first 70.3, cap your bike at approximately 70-75% of your functional threshold power if you use power, or 80-85% of max heart rate if you use HR. If you have neither, use perceived effort: "I could keep going like this for at least another hour" at the halfway point. If you can't say that at km 45, you're too hot.
- Run — start easy, build after km 7. The first 5-7 km of the half marathon should feel suspiciously easy. If it doesn't, you're running too hard. After km 7, if you feel good, start lifting effort gradually. If you don't feel good, hold pace and survive. The back half is where everyone slows — you want to slow least.
Walk the aid stations. Drink at every aid station. Eat a gel every 20-25 minutes. Do not try to be a hero in the first half of the run.
Common mistakes first-timers make
- Going out too hard on the bike. Adrenaline + fresh legs + a flat first 20 km = disaster. Commit to a cap and stick to it for the first hour.
- Under-fueling. 60-90 g carbs/hour on the bike, starting from minute 15. You can't "catch up" later.
- Over-hydrating with plain water. Hyponatremia is real. Use electrolytes, not just water. Especially in heat.
- New gear on race day. New shoes, new tri suit, new nutrition, new goggles — any of these can wreck your race. Everything you wear should have at least 4 hours of training time on it.
- Skipping bricks. Running off the bike is its own skill. Every week should include at least one short run off the bike, even 15 minutes.
- Ignoring the recovery week. Weeks 4 and 8 are lighter on purpose. Skipping them because "I feel fine" leads to injury in Week 9.
- Taper panic. In Week 11 your legs will feel heavy and sluggish. This is normal. Do not add sessions. Do not test yourself. Trust the work.
- Not practicing open water. Pool-only swim prep + race day in a wetsuit in a cold lake = panic. Do at least 4-6 open water swims before race day.
What happens after 70.3
Most first-time 70.3 athletes do one of three things after their race: (a) never race again and tell the story at dinner parties, (b) do a second 70.3 to beat their first time, or (c) sign up for a full-distance Ironman within 48 hours of finishing.
If you're in category (c) — and a surprising number of first-timers are — the jump from 70.3 to full-distance Ironman is not linear. A full Ironman is roughly 2.5-3x the physical effort of a 70.3, not 2x. Training volume goes from 10-12 hours/week peak to 15-18 hours/week peak. Nutrition becomes a much bigger problem. Mental preparation matters more than fitness.
If you want to see what that journey looks like from the inside, I'm in it right now: read my live first-Ironman training log. I went from 70.3 to Challenge Roth 2026 as my first full-distance race, and I'm documenting every week — the hours, the sessions, the mistakes, the life trade-offs.
But first: finish the 70.3 in front of you. One race at a time.
Frequently Asked Questions
How long does it take to train for a 70.3 from scratch?
If you have a base of general fitness (you can run 30 minutes continuously, ride a bike for an hour, and swim a few lengths without stopping), 12 weeks is enough to finish a 70.3 safely. If you're starting from zero — no running, no swimming, no cycling — plan on 6 months minimum: 3 months of base building across all three disciplines, then a 12-week structured plan. The swim is almost always the limiter for absolute beginners; it takes longer to adapt than bike or run.
Can I do a 70.3 without a coach?
Yes, for your first one. A written plan and the discipline to follow it gets most first-timers across the line. A coach becomes genuinely useful when (a) you're chasing a time goal, (b) you have injury history and need session-level adaptation, or (c) you're balancing training with a demanding job and need someone to tell you which session to drop. For a first 70.3 where the goal is to finish, self-coached with a plan like this one is perfectly reasonable.
How many hours a week do I need to train for a half Ironman?
For a first 70.3 with a finish-line goal, plan on 8-12 hours per week on average across a 12-week block, peaking at 12-14 hours in the two hardest weeks. Below 7 hours/week and you won't have enough time in the saddle. Above 15 hours/week for a first-timer and you're almost certainly over-training relative to your experience. Most first 70.3 finishers complete their prep on 9-10 hours/week average.
Is a road bike good enough for 70.3?
Yes. A road bike with clip-on aero bars will get you through a first 70.3 with zero compromise on finish time. Triathlon-specific bikes (TT/tri bikes) are faster — maybe 10-20 minutes over 90 km for a fit age grouper — but they also cost 2-3x more, handle worse in crosswinds, and are less comfortable if you're still building fitness. Do your first 70.3 on whatever bike you already ride. Upgrade later if you commit to the sport.
What's a realistic finish time for a first 70.3?
For a fit first-timer who follows a 12-week plan, expect 6:00 to 7:30. Breakdown: swim 35-50 min, T1 5 min, bike 3:00-3:45, T2 3 min, run 2:00-2:45. Strong athletes with triathlon background can go sub-5:30 on their first one; back-of-pack finishers with light training hit 7:30-8:00. The published cutoff at most 70.3 races is 8:30 from your individual wave start.
Do I need a pool to train for 70.3?
A pool makes swim training much easier but it's not strictly required. You can prepare for a 70.3 swim entirely in open water if you have reliable lake or sea access and a wetsuit — this is how a lot of European age groupers train. What you cannot skip is swim-specific volume: you need to be in the water 2-3x per week. A bathtub is not a pool; a lake-only plan works only if you can swim year-round.
Can I run a half marathon off the bike in a 70.3?
Yes, but it will feel very different from a standalone half marathon. Expect your 70.3 run pace to be 20-45 seconds/km slower than your flat half marathon PR. The legs are heavier, the core is tired, and you'll be dealing with nutrition and heat. This is why brick sessions (short run immediately after a bike) are non-negotiable in the plan — your body has to learn that specific transition.
Should I do a sprint or Olympic before a 70.3?
Strongly recommended. A sprint triathlon (750m / 20km / 5km) in weeks 4-6 of your plan teaches you transitions, wetsuit swimming in a mass start, and race-day nutrition under zero-consequence conditions. An Olympic-distance race (1.5km / 40km / 10km) in week 8 works as a perfect B-race rehearsal for your 70.3. If you've never raced a triathlon before, at least do one sprint before your 70.3.
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