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Carbs{{ resultsReady ? `${formatNumber(computation.normalizedInputs.carb_target_gph, 0)} g/h` : '—' }} Fluid{{ resultsReady ? `${formatNumber(computation.values.fluid_rate_lph, 2)} L/h` : '—' }} Portable fuel{{ resultsReady ? fuelUnitRateLabel : '—' }}
Choose the activity for this single session.
From 30 minutes to 12 hours.
min
Set 0–120 g/h; higher rates should be practiced before an important session.
g/h
Enter your planned or measured rate. A value of 0 uses the 0.75 L/h illustration.
L/h
The planner assigns the remaining carb target to portable fuel.
g/L
Used to report planned intake beside the sweat-loss reference.
mg/L
Enter the amount you can actually carry in one bottle.
mL
Use 0 when the drink alone supplies the target.
g/unit
This is not a replacement prescription; it estimates loss context at the selected fluid rate.
The neutral value 0 keeps the visible reference profile.
mg/L
The neutral default is 0 mg.
mg/unit
The neutral default is 0, which disables the theoretical dose equivalent.
mg/dose
Choose 10–60 minutes; 30 minutes keeps the default schedule compact.
min
Fuel plan
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{{ carbGuidanceTitle }}{{ carbGuidanceText }}
Hydration and sodium are individual.Use measured sweat data from similar conditions when available. Avoid gaining body mass during exercise, and treat the sodium comparison as context rather than a dose recommendation.

The chart renderer is unavailable. The same source values remain available in the fuel plan.

WindowCarbsFluidFuel unitsSodium intakeCopy
{{ row.window }}{{ row.carbs }}{{ row.fluid }}{{ row.fuelUnits }}{{ row.sodium }}
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A fuel plan can look sensible by the hour and still fail when it is turned into bottles, packets, and decisions made while tired. Endurance fueling connects three rates: carbohydrate for working energy, fluid for hydration, and sodium supplied by drinks or portable food. Duration turns each hourly rate into a session total, while the available products determine whether that total can be carried and consumed in repeatable portions.

Quantity Useful basis Common planning error
CarbohydrateGrams per hour that have been rehearsedChoosing a high target without testing product mix or gut tolerance
FluidLiters per hour measured in similar weather and effortDrinking to a fixed number that exceeds actual losses
SodiumMilligrams per hour from the planned fluid and foodTreating estimated sweat loss as a prescription for full replacement
Carry planBottle and fuel portions available between refillsPlanning totals that cannot be carried or divided into usable servings

Carbohydrate needs change with session length, intensity, training status, and tolerance. Published guidance often uses 30 to 60 g/h during longer endurance exercise and allows intakes up to about 90 g/h for sessions beyond roughly 2.5 hours, but the upper end normally requires practice. A target is useful only when the athlete can digest it at the planned effort.

Fluid and sodium vary more between athletes and conditions than a generic schedule can capture. A sweat-rate measurement from a similar run or ride gives a stronger starting point than a broad illustration. Sweat sodium concentration is also individual, and an unmeasured reference profile is context rather than a dose recommendation.

Overdrinking is a serious limit on any hydration plan. Sodium does not make excessive fluid intake safe, and gaining body mass during exercise is a warning that intake may be outrunning losses. The safest plan is rehearsed in training, adjusted for the route and weather, and simple enough to follow without saving most intake for the end.

How to Use This Tool:

Build one session at a time, starting with rates you can defend from training rather than the largest values the fields allow.

  1. Choose Sport, enter Moving duration, and set the carbohydrate target in g/h. The sport choice labels the plan; it does not change the arithmetic.
  2. Enter a planned or measured Fluid rate. A value of 0 does not mean no fluid; it selects the built-in 0.75 L/h illustration, which should be replaced when you have a better estimate.
  3. Describe the prepared drink, bottle volume, and one portable-fuel portion. The remaining carbohydrate target is assigned to that portable portion only when its carbohydrate value is above 0.
  4. Choose a Sweat-sodium reference or enter a measured concentration. A positive measured value overrides the profile. Add sodium from the drink and portable fuel only when those values match the products you will use.
  5. Set a reminder interval from 10 to 60 minutes, then review the hourly rates, session totals, and each intake window. Round the result into portions you can actually carry while keeping the intended hourly average visible.

Interpreting Results:

Read planned carbohydrate beside the selected target. An uncovered carbohydrate target means the drink does not meet the target and the portable-fuel carbohydrate is 0, so no serving count can be calculated. Decimal bottle and fuel counts preserve the rate calculation; they still need practical rounding.

  • Use the entered fluid rate when it comes from a comparable training session. If the plan says its fluid basis is illustrative, do not mistake 0.75 L/h for a personal sweat-rate estimate.
  • Treat sodium loss reference and sodium gap reference as comparison values. They do not diagnose hydration status or prescribe salt doses.
  • The reminder schedule divides the same hourly plan into time windows. Changing the interval changes the row size, not the hourly or full-session totals.
  • Stop and reassess if the plan implies fluid above observed tolerance, body-mass gain during exercise, or carbohydrate intake that has not been practiced.

Technical Details:

The model combines constant hourly rates over one session. It does not predict changing sweat rate, aid-station availability, stomach tolerance, or product absorption. A positive entered fluid rate is used directly; otherwise the calculation uses 0.75 L/h. A positive measured sweat-sodium concentration overrides the selected 300, 600, 900, or 1,200 mg/L reference profile.

Formula Core

Duration converts minutes into hours, and every session total is the corresponding hourly rate multiplied by that duration.

H=D60 , Qtotal=Qhour×H

D is moving duration in minutes, H is hours, and Q can be fluid, carbohydrate, sodium, bottles, or portable-fuel portions. Full precision is retained in the calculation; visible values may be rounded.

Drink carbohydrate is set by fluid volume and drink concentration. Portable fuel fills the non-negative remainder when one serving contains carbohydrate.

Cdrink=F×K , R=max(0,T−Cdrink) , U=RG

F is fluid in L/h, K is drink carbohydrate in g/L, T is the carbohydrate target in g/h, G is grams in one portable-fuel portion, and U is portions per hour. When G is 0, U is set to 0 and the remainder is reported as uncovered.

The sodium comparison uses the same fluid and fuel rates. It never converts the remaining gap into a recommended dose.

Naloss=F×Nasweat , Naintake=F×Nadrink+U×Nafuel , Nagap=max(0,Naloss−Naintake)

Sweat and drink concentrations use mg/L, while the resulting rates use mg/h. If a positive salt-dose reference is entered, the displayed theoretical equivalent is the gap divided by milligrams per dose; a value of 0 disables that comparison.

Schedule mechanism

Each row spans from its start minute to the smaller of the next reminder boundary or the session finish. For a window lasting w minutes, every hourly quantity is multiplied by w/60. A final partial window therefore receives a proportional amount instead of being rounded up to a full interval.

Limitations, Privacy, and Safety Notes:

This is an informational planning model, not medical or dietetic advice. It cannot account for illness, medications, acclimatization, gastrointestinal problems, kidney or cardiovascular conditions, or an emergency during exercise.

  • Carbohydrate targets above familiar intake should be tested gradually during training.
  • Do not use the sodium gap to justify overdrinking. Sodium supplementation does not prevent exercise-associated hyponatremia when fluid intake remains excessive.
  • The calculations run in the browser and entered plan values are not sent to a calculation service. Shared or downloaded results can still contain personal fueling information.
  • Seek urgent medical help for confusion, seizures, collapse, severe breathing difficulty, or other serious symptoms during or after exercise.

Worked Example:

Three-hour ride with measured sweat data

A rider targets 60 g/h of carbohydrate and 1.0 L/h of fluid. A 30 g/L drink supplies 30 g/h, leaving one 30 g portable-fuel portion per hour. With measured sweat sodium of 1,000 mg/L, drink sodium of 400 mg/L, and 100 mg in each fuel portion, planned sodium intake is 500 mg/h beside a 1,000 mg/h loss reference. The three-hour totals are 180 g carbohydrate, 3 L fluid, three fuel portions, and 1,500 mg planned sodium. The 500 mg/h sodium gap remains context, not a replacement instruction.

References: