Full Ironman: 20-Week Training Plan
A 20-week plan to take you from Half Ironman fitness to finishing a full Ironman. Volume tables, race-week protocol, and honest logistics.
Overview
A full Ironman — 3.8km swim, 180km bike, 42.2km run — is a life event, not just a race. Finishing requires twenty weeks of consistent work, careful recovery, and a willingness to restructure your life around training. This plan assumes you've completed a Half Ironman and have a current 70.3 time under 7 hours (or equivalent endurance base). If you haven't, do the Half Ironman plan first.
The plan is designed around 12-15 hours of training per week peaking at 18-20 hours for the biggest weeks. If you can't commit that time over five months, this isn't the right plan for you yet — and that's fine. An Ironman will wait.
Golden Rule: Finishing an Ironman is about accumulated aerobic capacity and metabolic efficiency, not speed. The athletes who DNF are usually the ones who trained too hard too often; the ones who finish are the ones who showed up consistently at moderate intensity.
Prerequisites
- Half Ironman finished in under 7 hours in the last 12 months
- Ability to swim 2km continuous, bike 4 hours continuous, run 2 hours continuous — separately
- No major injuries in the last 6 months
- 15+ hours per week available for training across the plan
- A bike that's been race-fit recently and a coach or experienced friend who can assess your swim stroke
The 20-Week Block Structure
| Phase | Weeks | Focus |
|---|---|---|
| Base | 1-6 | Aerobic volume, low intensity, mobility work |
| Build 1 | 7-11 | Progressive volume, tempo intensity, first century ride |
| Build 2 | 12-16 | Peak volume, race-pace specificity, long bricks |
| Taper | 17-19 | Reduce volume, maintain intensity, logistics prep |
| Race | 20 | Race week |
Every fourth week is a recovery week: reduce volume 30-40%, keep one intensity session.
Weekly Volume Targets
| Phase | Swim | Bike | Run | Total |
|---|---|---|---|---|
| Base | 8-10 km | 150-200 km | 40-50 km | 12-14 hours |
| Build 1 | 10-12 km | 200-280 km | 55-65 km | 14-16 hours |
| Build 2 | 12-14 km | 280-380 km | 65-80 km | 17-20 hours |
| Taper | 6-8 km | 120-180 km | 30-40 km | 8-10 hours |
Numbers are indicative — adjust based on how your body responds. If you're accumulating fatigue faster than these suggest, back off 10-15%.
The rest of this plan is for supporters
You’ve read the overview. The full Advanced programme — the week-by-week schedule, the sessions, the progressions and the numbers — unlocks with an access code, from £0.67 a month. Every Beginner and Intermediate guide on the site stays free.