Half Ironman Triathlon: Distances, Times and Training

Also called 70.3, Middle distance, Half distance.

A half Ironman is a 1.9 kilometre swim, a 90 kilometre bike and a 21.1 kilometre run, which is a half marathon. The three legs total 70.3 miles, which is where the name comes from. Most finishers take between 5 and 7 hours, and nutrition becomes a limiting factor rather than an afterthought.

Distance breakdown

  • Swim: 1.9km (1.18 miles)
  • Bike: 90km (55.9 miles)
  • Run: 21.1km (13.1 miles)
  • Total: 113km (70.2 miles)

Typical finish times

  • Elite: Under 3:50
  • Advanced: 4:30 to 5:15
  • Intermediate: 5:15 to 6:15
  • First-timer: 6:15 to 7:30

Ranges, not targets. Course profile, heat and water conditions move every one of these on the day.

Training load

  • Weekly hours: 8 to 14 hours
  • Prep time: 16 to 20 weeks
  • Longest sessions
  • Swim: 60 minutes
  • Bike: 3 to 4 hours
  • Run: 1 hour 45

Each leg of a half ironman triathlon

The swim (1.9km)

35 minutes to an hour depending on ability and conditions. Long enough that a wetsuit makes a material difference where the rules allow one. Pacing matters more than at shorter distances: arriving at T1 with your heart rate under control sets up the next five hours.

The bike (90km)

Two and a half to three and a half hours, and the leg that defines your day. You need to eat and drink on the bike, because you cannot make up a calorie deficit on the run. Most first-timers under-fuel here and pay for it in the last 10km of the half marathon.

The run (21.1km)

A half marathon off the bike, usually 1 hour 45 to 2 hours 30. Expect to be considerably slower than a standalone half. This leg is largely decided by what happened in the previous four hours: pacing and fuelling, not run fitness.

How it compares to the other distances

Standard triathlon distances compared by swim, bike, run and total
DistanceSwimBikeRunTotalTypical finish
Super Sprint400m10km2.5km12.9km (8 mi)45 to 60 minutes
Sprint750m20km5km25.75km (16 mi)1:15 to 1:30
Olympic1.5km40km10km51.5km (32 mi)2:30 to 3:00
Half Ironman1.9km90km21.1km113km (70.2 mi)5:15 to 6:15
Ironman3.8km180km42.2km226km (140.4 mi)12 to 14 hours

The typical finish column shows the intermediate band for each distance.

Who this distance suits

Athletes with at least one Olympic-distance finish and the schedule for consistent long weekend sessions. This is the distance where triathlon stops being a fitness activity and starts being a logistics and nutrition problem.

  • The three legs total 70.3 miles, hence the name
  • Nutrition becomes a limiting factor, not an afterthought
  • Needs 8 to 14 hours a week over 16 to 20 weeks
  • A dedicated tri bike starts to pay for itself, though a road bike still finishes
  • Expect several days of recovery, not several hours

Common questions

How long is a half Ironman?

A half Ironman is a 1.9 kilometre swim, a 90 kilometre bike and a 21.1 kilometre run. Those add up to 70.3 miles, which is why the distance is branded 70.3.

How long does a half Ironman take?

Most age-group athletes finish between 5 and 7 hours. Competitive age-groupers come in around 4:30 to 5:15, and professionals go under 3 hours 50. Course profile and heat move these numbers more than at shorter distances.

How long should I train for a half Ironman?

Sixteen to twenty weeks is the usual plan length for someone with an Olympic-distance background, on eight to fourteen hours a week. The limiting factor is rarely fitness. It is the ability to protect a three to four hour ride most weekends.

Can I do a half Ironman as my first triathlon?

It is possible but not advisable. You would be learning open-water starts, transitions and race nutrition simultaneously over five or more hours. Doing a sprint and an Olympic first means the only new variable on 70.3 race day is duration.

Guides for this distance