Estimate your daily and total carbohydrate targets for a pre-race carb-loading phase, based on body weight and grams-per-kilogram sports-nutrition guidelines.
Quick Facts
Method
Carbohydrate intake scaled to body mass (g/kg/day)
Sports-nutrition guidelines for events over 90 minutes typically call for 7-12 g of carbohydrate per kg of body weight per day for 1-3 days before the event. Carbohydrate provides about 4 kcal per gram.
Results
Calculated
Daily Carb Target
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Grams per day during loading
Total Loading Carbs
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Grams over the whole loading period
Calories From Carbs
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Per day, at 4 kcal per gram
Per-Meal Target
—
Assuming 4 meals per day
Ready
Enter your body weight and loading plan, then press Calculate.
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How to use this calculator
This calculator estimates how much carbohydrate to eat during a pre-race carb-loading phase. Enter your body weight, pick a loading intensity, and set the number of loading days, then click Calculate to see your daily carb target, total grams for the loading period, calories from carbs, and a per-meal estimate. Click Clear to reset all fields.
The formula
Carb loading is dosed by body mass: daily carbohydrate (g) = body weight (kg) × grams per kilogram per day. Sports-nutrition guidance for endurance events lasting longer than about 90 minutes generally recommends 7 to 12 g/kg/day, depending on event length and how aggressive the protocol is. The total for the loading phase is simply the daily figure multiplied by the number of loading days, and calories from carbs are the daily gram total multiplied by 4 kcal per gram (the standard energy value of carbohydrate). If your weight is entered in pounds, it is converted to kilograms first (1 kg = 2.20462 lb) before the target is applied.
Choosing an intensity
Light (7 g/kg/day) fits events roughly 90 minutes to 2 hours long. Standard (10 g/kg/day) is the widely used target for marathons, half-Ironman races, and similar mid-distance endurance efforts. Aggressive (12 g/kg/day) matches short, high-carbohydrate rapid-loading protocols used before ultra-endurance events. This is a general planning estimate, not individualized medical or dietetic advice — athletes with diabetes or other conditions affecting carbohydrate metabolism should work with a sports dietitian or physician before changing intake.
Frequently Asked Questions
How much carbohydrate should I eat per day when carb loading?
Sports-nutrition guidelines for endurance events lasting longer than 90 minutes generally call for about 7 to 12 grams of carbohydrate per kilogram of body weight per day during the loading phase. Multiply your body weight in kilograms by your chosen g/kg target to get your daily gram goal.
How long should I carb load before a race?
The classic protocol loads for about 3 days before the event. Modern rapid protocols compress this to roughly 24 to 48 hours at the higher end of the g/kg range (around 10 to 12 g/kg/day) alongside reduced training volume. Events under 90 minutes typically do not need a dedicated loading phase.
What is the difference between the Light, Standard, and Aggressive settings?
Light (7 g/kg/day) suits events from about 90 minutes to 2 hours. Standard (10 g/kg/day) is the commonly used target for marathons, half-Ironman races, and similar mid-distance endurance events. Aggressive (12 g/kg/day) matches short, rapid-loading protocols used before ultra-endurance events.
Does this work for pounds as well as kilograms?
Yes. Choose lb as the weight unit and the calculator converts your weight to kilograms (1 kg = 2.20462 lb) before applying the grams-per-kilogram target, so the daily and total gram figures come out correctly either way.
Practical Guide for Carb Loading Calculator - Pre-Race Carbohydrate Strategy
Carb Loading Calculator - Pre-Race Carbohydrate Strategy is most useful when the inputs reflect the situation you are actually planning around, not a best-case estimate. Treat the result as a decision aid: it gives you a structured way to compare assumptions, spot outliers, and decide what to verify next. For Sports work, the most important review lens is repeatability, fatigue, recovery, pacing, training load, and conditions on the day.
Start with a baseline run using values you can defend. Then change one assumption at a time and watch which output moves the most. If one input dominates the result, spend your verification time there first. If several inputs have similar influence, use a conservative scenario and an optimistic scenario to create a practical range instead of relying on a single exact number.
Before acting on the result, compare the result with recent sessions, race logs, and coach feedback instead of relying on a single best effort. This is especially important when the calculator supports a purchase, project plan, performance target, or operational decision. The calculator can make the math consistent, but the quality of the conclusion still depends on current data, clear units, and assumptions that match your real constraints.
When the output looks surprising, slow down and inspect each input in order. A small change in one high-leverage field can move the final number more than several low-leverage fields combined. For Carb Loading Calculator - Pre-Race Carbohydrate Strategy, that means you should first confirm the value with the greatest scale, then confirm the value with the greatest uncertainty, then rerun the calculator with conservative and optimistic assumptions. This sequence turns the calculator from a single answer into a practical decision range.
Review Checklist
Confirm every input uses the unit and time period requested by the calculator.
Run a low, expected, and high scenario so the answer has a useful range.
Check whether rounding or a missing decimal place changes the decision.
Update the calculation each training block, after a tune-up event, or when volume and intensity change.