Calculator · Race-day fueling

Triathlon race-day fueling planner.

Hourly carb / fluid / sodium targets · bottle & gel inventory · transitions · aid stations · printable cheat sheet

Build your complete fueling and hydration plan for a Sprint, Olympic, 70.3, or full Ironman. Enter your weight, sweat rate, race splits, and conditions; pick your products from the database (Maurten, SiS, PF, GU, Neversecond, Mortal, Precision, plus IM aid-station classics like coke, banana, broth). Get a minute-by-minute schedule, glycogen trajectory, race scorecard, and a one-page cheat sheet you can print and tape to your top-tube.

Start planning ↓ How it works

Athlete & environment

Height (cm)

Weight (kg)

Conditions

Bike sweat rate (L/h) ⓘMeasure by weighing before/after a 1h workout. Typical range: 0.5–2.5 L/h. Changing conditions auto-adjusts these values.

Run sweat rate (L/h) ⓘRunning sweat rate is usually 10–20% higher than biking due to less airflow cooling. Adjust based on your data.

Sweat type

Sweat sodium (mg/L)

Sweat type presets sodium; override if you have lab data.

Race details

Race distance Race start (HH:MM)

Swim split (min)

Bike split (min)

Run split (min)

Bike power (W)

Fueling mode

Fueling mode ⓘMinimum: conservative, for shorter races or untrained guts. Recommended: balanced for most athletes. Maximum: aggressive, requires trained gut & dual-transport carbs.

Run CHO vs bike ⓘRunning reduces GI tolerance. 75% means your run carb target is 75% of bike. Override higher if you’ve trained your gut for running intake.

Caffeine strategy ⓘCaffeine peaks ~45–60 min after ingestion. Late Bike places tabs in the last 1–2 h of bike so they peak during the run. Run Only saves all caffeine for the run.

Starting glycogen (g) ⓘEstimated glycogen stores after carb loading. Default = weight × 7g (well carb-loaded). Range: 5–10 g/kg depending on loading protocol.

Bike CHO override (g/h) ⓘLeave empty to use the auto-computed bike target from race duration. Set a value if the athlete has trained their gut to a specific intake (e.g. 100 g/h).

Run CHO override (g/h) ⓘLeave empty to use the auto-computed run target (default = bike target × run factor, typically 75%). Override if the athlete has trained their run gut higher.

CHO targets based on total race duration. Run discount reflects reduced GI tolerance. Glycogen default = weight × 7. Overrides bypass the auto-computation per leg.

Hydration strategy

Bike fluid replacement ⓘPercentage of sweat loss to replace via drinking. 100% = drink back everything you sweat. Some athletes tolerate 80–90% to reduce GI load.

Run fluid replacement ⓘAuto: allows up to 2% body weight loss, a widely accepted safe threshold. Manual: set your own replacement percentage.

Auto-use sodium & caffeine tablets at the hour mark (if carried)

Energy & hydration summary

Carried at race start

Bike, bottles, gels, tablets

Drink 1

Count

Drink 2

Count

Drink 3

Count

Gel A

Gels A

Gel B

Gels B

Gel C

Gels C

Tablet A

Count

Tablet B

Count

Run, flasks, gels, tablets

Flask 1

Count

Flask 2

Count

Gel A

Gels A

Gel B

Gels B

Gel C

Gels C

Tablet A

Count

Tablet B

Count

Transitions

T0 (−15 min)
Enable T0

T1
Allow nutrition in T1

T2
Allow nutrition in T2

T1 time (min)

T2 time (min)

T0 selections

Drink 1

Serv.

Drink 2

Serv.

Gel/Solid

Count

Tablet A

Count

Tablet B

Count

T1 selections

Drink 1

Serv.

Drink 2

Serv.

Gel/Solid

Count

Tablet

Count

T2 selections

Drink 1

Serv.

Drink 2

Serv.

Gel/Solid

Count

Tablet

Count

Aid stations

Bike aid-stations

Enable bike aid-stations

Frequency (km)

Drink A (bottles/station)

Drink B (bottles/station)

Drink C (bottles/station)

Bike station bottles add to your on-bike bank; you sip evenly over time.

Run aid-stations (cups)

Enable run aid-stations

Frequency (km)

Run drink ACups/station (150 ml)

Run drink BCups/station (150 ml)

Run drink CCups/station (150 ml)

Run cups are consumed at the station (not carried).

Pre-race guidance

Race scorecard

Schedule

Time	Segment	CHO (g)	kcal	Fluid (ml)	Sodium (mg)	Potassium (mg)	Caffeine (mg)	Products / notes

Notes

Breakfast target depends on expected race duration; also take ~25 g CHO 15 min before start.
Gels may be taken with water or sports drink; prefer water when possible.
Bike: liquids are sipped evenly from your carried bottles; aid-stations refill your bank.
Run: cups (150 ml) are consumed at the station; choose cups/station to match your needs.
Recovery: within 30–60 min, aim ~60–90 g carbs + 15–25 g protein; hydrate ~150% of fluid lost.

Glycogen trajectory

Fueling timeline

Race-day cheat sheet

How the planner builds your race-day schedule

1. Targets

Hourly carb / fluid / sodium targets

Your weight, sweat rate, and total race duration set the per-hour targets. The carb matrix scales with race time (Sprint sips, Ironman approaches 90–120 g/h). Run carbs default to 75% of bike to reflect reduced GI tolerance, override if you’ve trained your gut higher.

2. Inventory

Pick your products from a real database

120+ products: Maurten 100 / 160 / Mix 320, SiS GO + Beta Fuel, Precision PF 30, GU, Neversecond C30 / C90, Mortal, Torq, High5, plus IM aid-station classics (flat coke, broth, banana, pretzels, orange slice). DIY super-syrup bottles up to 40% CHO. Mix three gel types per leg to combine caffeinated + plain.

3. Transitions

T0, T1, T2 are real fueling windows

T0 (−15 min) is your pre-swim deposit. T1 is post-swim refuel. T2 is the run handover. Each gets its own products and counts toward the appropriate leg total, the planner knows pre-swim glucose lands in your bloodstream during the swim, not before it.

4. Aid stations

Course aid plays into the math

Set bike aid frequency (km) and what you grab per pass, bottles refill your on-bike bank and drain over time. Run aid stations dispense 150 ml cups; pick the drink and how many cups you grab. The schedule slots them at the actual time you arrive based on your pace.

5. Schedule + scorecard

Hour-by-hour minute-by-minute plan

15-minute granularity for the first hour, hourly summaries with target-vs-actual for CHO / fluid / sodium. Race scorecard at the bottom: how close you got to targets, projected body-weight loss (red >3.5%), caffeine load (mg and mg/kg), and what’s left in your bottles at the finish.

6. Cheat sheet

Print or export, tape it to your top-tube

Race-day PDF strips the inputs and shows: a one-page briefing (hourly targets + race totals + carry list + aid plan + transitions), then the cheat sheet (what / when), then glycogen trajectory and timeline. Export CSV for further editing or to import into a coach’s spreadsheet.

Coach note

A plan is the floor, not the contract.

Most race-day fueling plans fail because they’re built top-down (textbook number) instead of bottom-up (what your gut actually tolerates). Three rules I make every athlete follow:

Train every product on race day. Don’t take Maurten 320 in the bottle for the first time at IM Lanzarote. Every bottle, gel, and tablet on the cheat sheet should have been tested at race intensity for at least three long sessions.
Practice the transitions. T1 / T2 are not a bonus, they’re ~50–100 g of CHO and 250–500 ml of fluid each. Drill them in brick workouts so they happen automatically when you’re cooked.
Have a downside plan. If you can’t hit 100 g/h on the bike, what’s your 70 g/h fallback? The planner’s “Recommended” mode is the goal; “Minimum” is the bailout. Know both before the gun.

What this calculator can’t do: tell you what your gut will tolerate at 88% CP in 32°C heat. That’s a training adaptation, not a number. The plan is the input; how you build the gut to execute it is the work.

Race-prep coaching Performance Lab

Related calculators

Intra-workout fueling

Quicker version: hourly carb target for any workout duration with food-equivalent and DIY mix breakdowns. Good for training days.

Open → Sweat rate

Measure your bike + run sweat rate from a weigh-in protocol, the most important input for fluid & sodium targets above.

Open → Power to finish (course-based)

Pair the fueling plan with a realistic race-time prediction on your actual course (Kona, Lanzarote, every IM 70.3 worldwide).

Open →

Want a coach to build the plan and rehearse it with you?

The planner is the input. Race-prep coaching turns it into the actual race-day brief: which bottles go where on the bike, what you tell special-needs to put in your bag, the bailout plan if your stomach turns, the heat-adjusted version. Built around your gut, your sweat data, and the specific course.

Coaching Send feedback

Spotted a bug, want a product added to the database, or have feedback? Email info@yousuli.co.