Carb Load Calculator

Endurance Carb Loading Calculator

Kilograms (kg) Pounds (lbs)

Moderate (8g per kg body weight) Aggressive (10g per kg body weight) Elite / Maximum (12g per kg body weight) Most marathon runners aim for 10g/kg for 2-3 days before the race.

Your Daily Targets

Daily Total Carbs

0g

Carb Calories

0 kcal

Sample Meal Distribution

• 3 Meals per day (each): 0g
• 5 Small Meals/Snacks (each): 0g

function calculateCarbLoad() { var weight = parseFloat(document.getElementById('bodyWeight').value); var unit = document.getElementById('weightUnit').value; var multiplier = parseFloat(document.getElementById('loadIntensity').value); if (isNaN(weight) || weight <= 0) { alert("Please enter a valid body weight."); return; } var weightInKg = weight; if (unit === 'lbs') { weightInKg = weight / 2.20462; } var dailyCarbs = Math.round(weightInKg * multiplier); var calories = Math.round(dailyCarbs * 4); document.getElementById('totalCarbs').innerHTML = dailyCarbs + "g"; document.getElementById('carbCalories').innerHTML = calories + " kcal"; document.getElementById('threeMeals').innerHTML = Math.round(dailyCarbs / 3) + "g"; document.getElementById('fiveMeals').innerHTML = Math.round(dailyCarbs / 5) + "g"; document.getElementById('carbResultArea').style.display = 'block'; window.scrollTo({ top: document.getElementById('carbResultArea').offsetTop + 100, behavior: 'smooth' }); }

How to Use the Carb Load Calculator

For endurance athletes participating in events lasting longer than 90 minutes (like marathons, long-distance triathlons, or century rides), maximizing muscle glycogen stores is critical for performance. This calculator helps you determine exactly how many grams of carbohydrates you need to consume per day during your "loading" phase.

The Science of Glycogen Loading

Muscle glycogen is the primary fuel source for high-intensity endurance exercise. Under normal dietary conditions, your muscles store enough glycogen for about 90–120 minutes of activity. By increasing your intake to 8–12 grams of carbohydrates per kilogram of body weight in the 36–48 hours before an event, you can nearly double these stores, delaying the onset of fatigue (often called "hitting the wall").

Carb Loading Strategy Examples

• The 70kg (154lb) Marathoner: For an aggressive load (10g/kg), this athlete needs 700g of carbohydrates per day. This is roughly equivalent to 2,800 calories from carbs alone.
• The 90kg (198lb) Ironman Athlete: For a maximum load (12g/kg), this athlete requires 1,080g of carbohydrates per day.

Pro Tips for Successful Carb Loading

• Lower the Fiber: To avoid gastrointestinal distress on race day, choose low-fiber carbohydrates like white rice, white pasta, and peeled potatoes instead of whole grains.
• Hydrate: For every gram of glycogen stored, your body stores approximately 3 grams of water. Expect your body weight to increase slightly—this is a sign of a successful load.
• Reduce Fat and Protein: Since your carbohydrate intake will be very high, you must reduce fat and protein intake to stay within a reasonable total caloric range.
• Liquid Carbs: If you find it difficult to eat the required volume of food, use sports drinks, fruit juices, or smoothies to hit your targets.

Frequently Asked Questions

When should I start carb loading?
Most protocols recommend starting 48 to 72 hours before your race. Ensure you are also "tapering" (reducing exercise volume) during this time so your muscles aren't burning the fuel you are trying to store.

Will I feel bloated?
Some heaviness is normal due to the extra water weight. This "stored" water is actually beneficial, as it will be released and used for hydration as you burn through the glycogen during your race.