Half Ironman
Half Ironman / Ironman 70.3
A Half Ironman (70.3) is a middle-distance triathlon: 1.9km swim, 90km bike, 21.1km run. Learn what to expect, training requirements, and how to prepare for this challenging race.
Quick Answer
Half Ironman — A Half Ironman (officially Ironman 70.3) is a middle-distance triathlon consisting of a 1.9km swim, 90km bike, and 21.1km run (half marathon). The "70.3" refers to the total distance in miles. Finish times typically range from 4:30 to 8:00+ hours.
Half Ironman Distances
| Discipline | Distance (Metric) | Distance (Imperial) |
|---|---|---|
| Swim | 1.9km | 1.2 miles |
| Bike | 90km | 56 miles |
| Run | 21.1km | 13.1 miles |
| Total | 113km | 70.3 miles |
The distance is exactly half of a full Ironman.
Half Ironman Finish Times
| Level | Swim | T1 | Bike | T2 | Run | Total |
|---|---|---|---|---|---|---|
| Beginner | 45-55 min | 6-8 min | 3:30-4:00 | 3-5 min | 2:30-3:00 | 7:00-8:30 |
| Intermediate | 35-45 min | 4-6 min | 2:45-3:15 | 2-3 min | 2:00-2:30 | 5:30-6:45 |
| Advanced | 28-35 min | 2-4 min | 2:20-2:45 | 1-2 min | 1:40-2:00 | 4:45-5:30 |
| Elite | 23-28 min | <2 min | 2:00-2:15 | <1 min | 1:15-1:30 | 3:45-4:15 |
Use our Half Ironman Calculator for personalized pace predictions.
Why 70.3?
The name "70.3" comes from the total race distance in miles:
- 1.2 mi swim
- 56 mi bike
- 13.1 mi run
- = 70.3 miles total
Ironman 70.3 is a registered trademark of the World Triathlon Corporation (WTC).
Training for Half Ironman
Time Commitment
| Goal | Training Hours/Week |
|---|---|
| Finish | 8-10 hours |
| Competitive | 10-14 hours |
| Podium | 14-18 hours |
Training Timeline
| Phase | Duration | Focus |
|---|---|---|
| Base | 8-12 weeks | Build aerobic volume |
| Build | 8-10 weeks | Add intensity, longer efforts |
| Peak | 3-4 weeks | Race simulation, bricks |
| Taper | 2 weeks | Reduce volume 40-50% |
Total: 20-28 weeks for adequate preparation.
Sample Peak Training Week
| Day | Workout | Duration |
|---|---|---|
| Monday | Swim | 60 min |
| Tuesday | Run intervals | 75 min |
| Wednesday | Bike + strength | 90 min |
| Thursday | Swim + short run | 90 min |
| Friday | Rest | — |
| Saturday | Long bike + brick run | 4-5 hours |
| Sunday | Long run | 90-120 min |
Read our complete Half Ironman Training Overview.
Race Day Strategy
Swim (1.9km)
| Strategy | Why |
|---|---|
| Relaxed start | Long day ahead |
| Sight every 8-10 strokes | Stay on course |
| Bilateral breathing | Balance and navigation |
| Target: 75-85% effort | Conservation |
Bike (90km)
| Strategy | Why |
|---|---|
| Stay in Zone 2-3 | Save legs for half marathon |
| Eat 200-300 cal/hour | Fuel the run |
| Drink 500-750ml/hour | Prevent dehydration |
| Don't race others | Race your own pace |
Run (21.1km)
| Strategy | Why |
|---|---|
| Start 30 sec slower than half marathon pace | Compensate for fatigue |
| Walk aid stations first half | Take in fluids properly |
| Build into second half | Negative split if possible |
| Manage the heat | Don't blow up |
See our Ironman Pacing Strategy guide.
Nutrition Strategy
Pre-Race
| Timing | Nutrition |
|---|---|
| Day before | 8-10g carbs/kg body weight |
| Race morning | 2-3g carbs/kg, 3 hours before |
| Pre-swim | Sips of water |
During Race
| Leg | Nutrition Target |
|---|---|
| Swim | Nothing |
| Bike | 60-80g carbs/hour |
| Run | 40-60g carbs/hour |
| Total | 400-600g carbs |
Hydration
| Condition | Fluid Target |
|---|---|
| Cool | 500-700ml/hour |
| Moderate | 700-900ml/hour |
| Hot | 900-1200ml/hour |
Read our Triathlon Nutrition Race Day Guide.
Half Ironman vs Other Distances
| Distance | Swim | Bike | Run | Typical Time |
|---|---|---|---|---|
| Sprint | 750m | 20km | 5km | 1:00-2:00 |
| Olympic | 1.5km | 40km | 10km | 2:00-3:30 |
| Half Ironman | 1.9km | 90km | 21.1km | 4:30-7:00 |
| Ironman | 3.8km | 180km | 42.2km | 9:00-17:00 |
Key Training Benchmarks
Before attempting a Half Ironman, aim to complete:
| Benchmark | Target |
|---|---|
| Swim | 2000m continuous |
| Bike | 3-hour ride at race pace |
| Run | 15km at easy pace |
| Brick | 2-hour bike + 45-min run |
Common Mistakes
1. Insufficient Bike Training
The 90km bike is the longest leg. Many athletes under-train cycling and pay for it on the run.
2. Running Too Fast Off the Bike
Your half marathon pace off a 90km bike is NOT your standalone half marathon pace. Start conservatively.
3. Nutrition Failures
4.5-7 hours of racing requires serious fueling. Practice your nutrition plan extensively in training.
4. Inadequate Taper
The taper is where fitness becomes performance. Don't skip it or cut it short.
Common Questions
How long does it take to train for a Half Ironman?
For athletes with a fitness base, 20-24 weeks is ideal. Complete beginners should plan 6+ months and consider completing shorter races first.
Can I do a Half Ironman without doing an Olympic first?
Yes, but it's not recommended. Olympic distance teaches race pacing, transitions, and nutrition at lower stakes.
What's a good Half Ironman time?
- Finishing: Under 7:00 is solid for beginners
- Competitive: Sub-5:30 is strong
- Elite age-group: Sub-4:45
Is Half Ironman harder than a marathon?
Different challenges. Half Ironman is longer (4.5-7 hours vs 3-5 hours) and requires three sports, but the run pace is slower. Most athletes find Half Ironman more demanding overall.