Carb Loading Calculator

Updated Sep 2026 Used 0 times

Set the loading targetNormalize body mass and choose the explicit g/kg/day target.

Body mass

Use current body mass; unit conversion occurs before the target is applied.

Carbohydrate target

Choose within the supported sports-nutrition range; higher is not automatically better.

Loading duration

Select the period you are calculating, not a guaranteed optimal protocol.

Turn it into a usable planDivide across eating occasions and keep during-event intake separate.

Meals and snacks per day

Used only to divide the daily target into equal planning portions.

Expected event duration

Used to show a separate broad during-event intake range.

Guest calculations stay on this device. Signed-in results sync privately.

Your result

Carbohydrate loading target

Enter your values, then calculate to see a verified result.

Inputs usedReview the information used for this result.

Full calculation and sourcesOpen Full calculation and sources to audit the inputs, formula sequence, assumptions, and source scope.

Versioned calculationFormula v1.0.0

Target stays visible

No hidden body-mass multiplier.

Meal-scale output

Turn a daily total into practical portions.

Strategies separated

Pre-event and during-event numbers do not blur together.

Set body massMetric or pounds normalize to kg.70 kg

Choose g/kg/dayKeep the target explicit.10 g/kg/day

Distribute practicallyUse meals and snacks.6 eating occasions

Interpretation

Carbohydrate supports glycogen availability.

Glycogen storage accompanies water.

A gram total is not personalized clinical nutrition.

Use this result

Translate grams into a dayReview daily, multi-day, and per-meal examples.Check suitability and toleranceReview conditions that need individual guidance.

Keep exploring

4 available tools

Running Race PlannerBuild an exact-time split, checkpoint, fuel, and start-delay plan.Sweat Rate CalculatorCalculate condition-specific sweat loss from a before-and-after test.VO2 Max CalculatorEstimate aerobic capacity from a measured Cooper 12-minute distance.Rucking Calorie CalculatorEstimate energy expenditure for loaded walking from terrain and load.

Public verification recordFormula v1.0.0

Review scope: Body-mass Normalization, 8-12 G/kg/day Arithmetic, Multi-day Totals, Kcal Conversion, Meal Distribution, And Separate Event-duration Bands.
Review team: CalculatorGeek Expert Review Team
Verified: 2026-09-27
Next source review: 2027-03-27
Automated fixtures: 5 cases

Review method

Recompute metric and pound cases; test both target boundaries, day counts, event-duration transitions, and invalid body mass.

Known limitations

The calculator does not determine whether carbohydrate loading is appropriate for the event or individual.
The gram target is not a complete meal plan and does not ensure micronutrient, protein, fat, fiber, or energy adequacy.
High carbohydrate intake can cause gastrointestinal discomfort and short-term water-associated mass gain.
Diabetes and other medical or dietary conditions require individualized professional advice.
During-event ranges are broad context and should be practiced rather than first attempted on race day.

Primary sources

Latest update

2026-09-27 · Added source-backed endurance calculation, premium result detail, public fixtures, and unified contextual navigation.

Published calculation checks

Case	Inputs	Expected result
70 kg at 10 g/kg for two days	body_mass_kg=70 kg, target_g_per_kg=10, loading_days=2, meals_per_day=6 count, event_duration_hours=4 hr	daily_carbohydrate_grams=700, loading_window_grams=1400, daily_carbohydrate_kcal=2800, during_event_low_gph=60, during_event_high_gph=90
154.324 pounds equivalent	body_mass_kg=154.323584 lb, target_g_per_kg=10, loading_days=2, meals_per_day=5 count, event_duration_hours=150 min	daily_carbohydrate_grams=700, grams_per_meal_or_snack=140, during_event_low_gph=30, during_event_high_gph=60
Eight gram lower bound	body_mass_kg=60 kg, target_g_per_kg=8, loading_days=1, meals_per_day=4 count, event_duration_hours=0.75 hr	daily_carbohydrate_grams=480, loading_window_grams=480, during_event_high_gph=0
Twelve gram upper bound	body_mass_kg=90 kg, target_g_per_kg=12, loading_days=3, meals_per_day=9 count, event_duration_hours=3 hr	daily_carbohydrate_grams=1080, loading_window_grams=3240, grams_per_meal_or_snack=120

On this page

Direct answer

The carb loading calculator multiplies body mass by a selected 8-12 g/kg/day target, then shows the daily total, multi-day total, carbohydrate calories, and per-meal share.

For a well-trained marathon runner, published sports-nutrition literature describes 10-12 g/kg/day over the final 36-48 hours. The calculator also shows broad during-event carbohydrate context separately so the two strategies are not confused.

Schedule a practiced during-race target in the Running Race Planner, and measure fluid loss separately with the Sweat Rate Calculator.

How to use the calculator

Enter body mass and choose the target deliberately.
Select the loading window you are evaluating.
Choose a practical number of meals and snacks.
Keep pre-event and during-event quantities separate.
Test food choices before race week and personalize when needed.

Inputs, outputs, and result meaning

Inputs

Body mass: Use current body mass; unit conversion occurs before the target is applied.
Carbohydrate target: Choose within the supported sports-nutrition range; higher is not automatically better.
Loading duration: Select the period you are calculating, not a guaranteed optimal protocol.
Meals and snacks per day: Used only to divide the daily target into equal planning portions.
Expected event duration: Used to show a separate broad during-event intake range.

Outputs

Daily carbohydrate target: Body mass multiplied by selected g/kg/day.
Loading-window carbohydrate: Daily target multiplied by selected days.
Carbohydrate energy: Daily carbohydrate grams multiplied by 4 kcal/g.
Grams per meal or snack: Equal-share planning amount, not a mandatory meal structure.
During-event lower reference: Broad lower during-event reference from duration.
During-event upper reference: Broad upper during-event reference from duration.

Formula and methodology

Daily target: body mass in kilograms x selected grams per kilogram per day.

Loading window: daily grams x selected days. Carbohydrate energy: daily grams x 4 kcal/g.

The during-event range is shown separately: 30-60 g/h for 1-2.5 hours and 60-90 g/h for events beyond about 2.5 hours in the cited sports-nutrition context. It is not added to the pre-event loading total.

Worked examples

70 kg athlete at 10 g/kg/day

70 x 10 = 700 g carbohydrate per day. Over two days, the arithmetic total is 1,400 g. Across six eating occasions, an equal planning share is about 117 g each.

60 kg at 8 g/kg/day

The daily target is 480 g. The lower target may be more practical, but target selection still depends on event demands and individual tolerance.

Interpretation and limitations

The calculator does not determine whether carbohydrate loading is appropriate for the event or individual.
The gram target is not a complete meal plan and does not ensure micronutrient, protein, fat, fiber, or energy adequacy.
High carbohydrate intake can cause gastrointestinal discomfort and short-term water-associated mass gain.
Diabetes and other medical or dietary conditions require individualized professional advice.
During-event ranges are broad context and should be practiced rather than first attempted on race day.

Frequently asked questions

How many grams per kilogram are used for carb loading?

This tool supports 8-12 g/kg/day and keeps the selected target visible. Marathon literature commonly describes 10-12 g/kg/day over 36-48 hours for well-trained runners.

Why did my body mass increase?

Stored glycogen is accompanied by water, so short-term scale increase can occur and is not automatically body-fat gain.

Is the per-meal number mandatory?

No. It is an equal-share planning aid; foods, appetite, tolerance, and schedule may require uneven distribution.

Are during-race carbs included in the loading total?

No. Pre-event loading and during-event intake are separate strategies and are reported separately.

Should everyone use 12 g/kg/day?

No. The highest selectable value is not automatically best or appropriate. Match the strategy to event demands and individual needs.

Sources and transparency

CalculatorGeek independently recomputed the public fixtures on 2026-09-27. Sources establish the method or its safe interpretation; they do not make a field estimate equivalent to laboratory measurement or individualized professional advice.