IRONMAN World Championship (Kona)
The most prestigious endurance event on earth. Lava fields, ocean humidity, headwinds across the Queen K Highway. Heat strain defines the day.
Kona is won or lost on bike-leg sodium. Front-of-field age groupers take 900 to 1400 mg per hour on the bike, dropping to 600 to 900 mg per hour on the run where absorption is lower. Humidity blocks evaporative cooling, so sweat rates run 20 to 30 percent above dry heat. Pre-load 1500 to 2000 mg sodium in the 24 hours before the start.
IM Kona Fueling Plan
For a 165 lb athlete finishing IM Kona in about 10 hr, plan roughly 65 g of carbs, 900 mg of sodium (1,250 mg for a salty sweater) and 1,050 ml of fluid per hour. That is about 650 g of carbs and 9,000 mg of sodium across the race.
| Finish time | Carbs | Sodium | Fluid |
|---|---|---|---|
| Front of field8 hr | 65 g/hr520 g total | 900 mg/hrsalty sweater 1,250 mg | 1,050 ml/hr8.4 L total |
| Mid-pack10 hr | 65 g/hr650 g total | 900 mg/hrsalty sweater 1,250 mg | 1,050 ml/hr10.5 L total |
| Back of pack14 hr | 55 g/hr770 g total | 850 mg/hrsalty sweater 1,150 mg | 1,000 ml/hr14 L total |
Computed by the free sodium and carb calculators for a 165 lb athlete in hot and humid conditions. Fluid is a planning figure for what to carry, not a drinking schedule: on the day, drink to thirst. Your own numbers move with body weight and sweat rate.
Where The Sodium Math Bends
Schematic profile · Cramping windows tend to cluster around major climbs and the descents that follow them
What's On Course
Ten bike aid stations run from bike mile 15.2 to 103.4, and 24 run aid stations sit 0.4 to 1.4 miles apart. Both serve water, cola, bananas, Precision 1000 electrolyte drink (1,000 mg sodium per litre) and Maurten Gel 160, Gel CAF 160 and Solid 160 bars; the run adds oranges, potato chips and chicken broth. Personal needs bags, food only, wait at bike mile 60.1 and run mile 16.9.
| Mile | Station | Cutoff |
|---|---|---|
| 2.4 | Swim exit | 2 hr 20 min from your swim start |
| 61.7 | Hawi turnaround, bike mile 59.3 | 2:40 PM |
| 62.5 | Bike personal needs, bike mile 60.1Your own bag, food only | |
| 95.9 | Scenic Point on the Queen K, bike mile 93.5 | 5:10 PM |
| 114.4 | Bike finish | 10 hr 30 min from your swim start |
| 131.3 | Run personal needs, run mile 16.9Your own bag, food only | |
| 133.1 | Kahilihili Drive at the Queen K, run mile 18.7 | 11:10 PM |
| 140.6 | Finish | 17 hr from your swim start |
Source: 2026 IRONMAN World Championship Kona athlete guide, 2026
75-92°F · high humidity
Climate
hot + humid
Humidity
high
Cutoff
17 hours
10-yr avg high
82°F
10-yr avg low
73°F
Record high / low
86° / 68°F
Years with rain
80%
The Cumulative Deficit Window
Kona is the sodium calculator stress test. Trade-wind heat plus high humidity means sweat does not evaporate efficiently, so cooling demands a higher sweat rate for the same workload. The bike leg crosses the Queen K Highway lava fields where radiant heat off black rock pushes apparent temperature 10-15F above ambient. The marathon back half on Alii Drive is where the famous Kona DNFs happen, almost always tracing back to cumulative sodium and fluid deficit from the bike leg. Pro and age-group winners consistently log sodium intake in the 1200 to 1800 mg per hour range across the bike.
Key Considerations
- Plan the bike leg sodium intake conservatively high. Most Kona DNFs trace back to under-fueling sodium on the bike, not the run.
- Humidity blunts evaporative cooling. Sweat rates in Kona run 20-30% higher than the same effort in dry heat.
- Pre-race sodium loading is non-negotiable. Add 1500-2000 mg sodium in the 24 hours before the start.
- The Energy Lab on the run course (mile 16-20) is the highest cramping window. Pre-dose 600 mg sodium at the mile 14 aid station.
Who Finishes, And How Fast
IRONMAN World Championship 2026 results
Men winner · 2026
Vincent Luis
7:47:27FRA
Women winner · 2026
Taylor Knibb
8:36:29USA
Free Tools, Pre-Filled For IM Kona
Tap any tool. We pre-load your event, climate, and sweat profile. Adjust your weight and finish target and the plan generates instantly.
Sodium plan
Per-hour sodium and fluid targets for IM Kona conditions.
Carb fueling
Hourly carb targets and a fuel menu calibrated to your weight and the IM Kona duration.
Heat protocol
10-14 day adaptation plan if you're racing into humidity.
Hydration audit
Weigh-in test that converts a 60-minute training session into a measured sweat rate.
Caffeine timing
Pre-race dose, mid-race top-ups, and race-week taper protocol for IM Kona timing.
Dig Into The Science
Beetroot Powder for Ironman: 5-Day Loading Protocol
Dietary nitrate loading for Ironman and 70.3 triathlon: the 5-day protocol, second-dose timing for events over 5 hours, and why betaine nitrate matters.
Stop Leg Cramps: Supplement Protocol & Risk Calculator
Leg cramps have two causes: electrolyte depletion and neuromuscular fatigue. Score yours with the free calculator, then load the 5 supplements that fix both.
Sodium Calculator for Endurance Athletes (Free Tool)
Sweat sodium varies 3 to 4x across athletes. A free sodium calculator that sets an hourly target from your body, sweat history, and race-day climate.
Your IM Kona Plan,
Built From Real Data.
Pro unlocks a per-leg sodium, fluid, and carb schedule keyed to the actual course: Kailua-Kona to the Hawi turnaround, Hawi to the Energy Lab, and Energy Lab to the finish, dosed for the Queen K heat.
- Your sweat rate, from a weigh-in test or your best estimate
- Per-leg sodium, fluid, and carb schedule keyed to the course profile
- Branded, printable PDF
- Post-race feedback capture so the next plan is sharper
Per race
Every race
Unlimited race plans today. Strava connection and the multi-event calendar are still in development.
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About IM Kona
How much sodium do Kona finishers typically take per hour?
Bike leg averages 900 to 1400 mg per hour for the front of the age-group field. Run leg drops to 600 to 900 mg per hour because absorption rate is lower under running impact. Total race sodium for a 10-hour finisher typically lands between 9,000 and 14,000 mg.
Why does Kona heat feel worse than other hot races?
Trade wind humidity. Most hot triathlons (Texas, Florida) have similar air temperatures but lower humidity, allowing evaporative cooling to keep core temperature manageable. Kona humidity blocks evaporation; sweat drips off rather than cooling you, so the same effort produces more heat strain.
Should I lower sodium intake on the run because of GI risk?
Slightly. Run-leg sodium intake is typically 60-75% of bike-leg intake due to lower absorption rates under impact. Switch from liquid electrolyte to capsules with water at the mile 13 aid station. Pre-loading on the bike makes the run-leg deficit more manageable.