IRONMAN 70.3 Boulder fuel plan: carbs, fluid and sodium per hour.
June 12, 2027, Boulder, Colorado, United States. Set your finish time and the plan follows.
- Distance
- 113 km
- Climbing
- 826 m, bike course
- Typical temperature
- 13 to 33 °C · 55 to 91 °F
- Aid stations
- See below
Your plan
70.3 (half distance) · 5 h 30 min
Carbs an hour
75g
The research range for this race is 60 to 90 g; your gut training sets where you start. Above 60 g, use glucose and fructose, about 2:1.
Jeukendrup 2014Viribay 2020+4 moreFluid an hour
To thirst
Without a sweat rate the research says drink to thirst. Do the sweat test to get a range.
NATA 2017ACSM 2007Sodium an hour
300 to 1,000mg
Nearer the top in the heat. A sweat sodium test gives you your own number.
Baker 2017NATA 2017+1 moreLeg by leg (typical splits for this distance)
- Swim36 minNo fuel
- Bike2 h 48 min210 g carbs
- Run1 h 56 min145 g carbs
About 365 g of carbs over the race (bike and run). That is a 25 g gel every 20 minutes, or the same carbs from drink and chews.
Rehearse it in training first: the gut adapts in 2 to 4 weeks. Costa 2017
Hand it to your AI
Your AI can check these numbers against your training and adjust them. The prompt has your results filled in.
See the prompt
I'm racing a 70.3 (half distance) and expect to finish in 5 h 30 min. I haven't measured my sweat rate. Conditions look hot, and my gut is in some training for fueling. A race fuel calculator built on the research (Jeukendrup 2014, the ACSM 2016 position stand) gave me: 75 g carbs an hour (glucose and fructose, about 2:1), about 365 g in total; fluid: drink to thirst, no sweat rate yet; 300 to 1,000 mg sodium an hour. Check this against my training and how my gut has handled fueling, then build my race day plan: what to take and when, leg by leg, with real products I can buy.
Gemini, Grok Bot, Dots, Muse and Cue: copy the prompt and paste it in.
With Memory.fit, your AI would already know your sweat rate.
On Android now: get it on Google Play. One email when the iPhone app is on the App Store.
The course
What to know about IRONMAN 70.3 Boulder.
Raced at altitude: the bike course starts at the Boulder Reservoir, 1,585 m (5,199 ft) above sea level, after a one loop swim in it. Two loop bike with short rollers and fast descents, then a two loop run around the reservoir, much of it on hard packed dirt roads.
On course: Precision Fuel & Hydration, Maurten Gel 100 and Gel 100 CAF, Maurten Solid 225 bars, cola, chips and pretzels on the run. Train with what the course hands out, or carry your own.
Bike aid stations about every 12 to 15 miles (19 to 24 km) and run aid stations about every mile (1.6 km).
Race details checked October 26, 2026 from ironman.com, ironman.com, ironman.com, ironman.com. Courses and aid stations change: check the official page in race week.
Train for it
Train for IRONMAN 70.3 Boulder with your AI.
With Memory.fit, your AI reads your real training, sleep and fuel, plans your weeks toward race day and shows the plan in the app.
Questions
IRONMAN 70.3 Boulder: questions.
At a typical finish of 5 h 30 min, the research range is 60 to 90 g an hour, as glucose and fructose, set by how trained your gut is. Enter your own finish time above for your number.
Typical race day low and high air temperature published by IRONMAN on the race page. run from about 13 to 33 °C (55 to 91 °F). Heat raises your sweat rate, so do a sweat test in similar weather.
Bike aid stations about every 12 to 15 miles (19 to 24 km) and run aid stations about every mile (1.6 km). Check the athlete guide in race week, as positions can change.
Not medical advice. Memory.fit is not affiliated with IRONMAN 70.3 Boulder or its organizer.
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