Carb Loading Calculator
Free Carb loading Calculator for hydration sports nutrition. Enter your stats to get performance metrics and improvement targets.
Reviewed by Sher, Sports Science & Nutrition Specialist
Formula
Daily Carbs (g) = Body Weight (kg) x Carb Rate (g/kg)
Where Body Weight is in kilograms and Carb Rate ranges from 7 g/kg for moderate to 12 g/kg for extreme endurance events. Glycogen storage is approximately 15-20 g per kg body weight in muscle.
Worked Examples
Example 1: Marathon Runner Carb Loading
Problem:A 70 kg marathon runner wants to carb load for 3 days before a race lasting approximately 3.5 hours at high intensity.
Solution:Carb target = 70 kg x 10 g/kg = 700 g carbs per day\nDaily carb calories = 700 x 4 = 2,800 cal\nTotal over 3 days = 2,100 g\nMax glycogen = 70 x 20 = 1,400 g\nNormal glycogen = 70 x 15 = 1,050 g\nExtra glycogen = 350 g = 1,400 cal
Result:Daily: 700g carbs (2,800 cal) | Total: 2,100g | Extra glycogen: 350g
Example 2: Triathlete Pre-Race Loading
Problem:A 60 kg female triathlete needs to carb load for 2 days before an Ironman event with extreme intensity demands.
Solution:Carb target = 60 kg x 12 g/kg = 720 g carbs per day\nDaily carb calories = 720 x 4 = 2,880 cal\nTotal over 2 days = 1,440 g\nMax glycogen = 60 x 20 = 1,200 g\nNormal glycogen = 60 x 15 = 900 g\nExtra = 300 g = 1,200 cal
Result:Daily: 720g carbs (2,880 cal) | Total: 1,440g | Extra glycogen: 300g
Frequently Asked Questions
What is carb loading and why do endurance athletes use it?
Carb loading, also known as glycogen supercompensation, is a nutritional strategy where athletes increase their carbohydrate intake in the days leading up to a major endurance event. The goal is to maximize glycogen stores in the muscles and liver beyond their normal resting levels. This extra glycogen provides additional fuel during prolonged exercise lasting more than 90 minutes. Research shows that carb loading can improve endurance performance by 2 to 3 percent, which can translate to several minutes in a marathon. The strategy works best for continuous activities like marathon running, long-distance cycling, triathlon events, and cross-country skiing.
How many grams of carbs per kilogram should I eat during carb loading?
The recommended carbohydrate intake during a carb loading phase depends on your event intensity and duration. For moderate intensity endurance events, aim for 7 to 8 grams of carbohydrates per kilogram of body weight per day. For high intensity events like marathons or long triathlons, you should target 10 grams per kilogram per day. For ultra-endurance events lasting many hours, some athletes consume up to 12 grams per kilogram per day. These amounts are significantly higher than normal training intake of 5 to 7 grams per kilogram. It is important to gradually increase intake rather than suddenly consuming massive amounts of carbohydrates to avoid digestive issues.
When should I start carb loading before an event?
The modern approach to carb loading recommends starting 2 to 3 days before your endurance event. Older protocols suggested a depletion phase followed by loading over 6 to 7 days, but research has shown that a shorter 2 to 3 day loading phase is equally effective and causes less gastrointestinal distress. During these loading days, you should simultaneously reduce your training volume to allow glycogen to accumulate in your muscles. The final meal before your event should be consumed 3 to 4 hours before start time and contain familiar, easily digestible carbohydrate-rich foods. Avoid trying new foods during the loading phase to prevent stomach issues on race day.
What are the best foods to eat during carb loading?
The best carb loading foods are those that are rich in carbohydrates but relatively low in fiber and fat to maximize absorption and minimize gastrointestinal discomfort. Excellent choices include white rice, pasta, bread, bagels, pancakes, potatoes, sweet potatoes, oatmeal, cereal, bananas, and dried fruit. Sports drinks and fruit juices can supplement solid food intake when you are struggling to eat enough. Many athletes find it helpful to eat smaller, more frequent meals throughout the day rather than three large meals. Foods like beans, high-fiber cereals, and cruciferous vegetables should be limited because they can cause bloating and gas before competition.
References
Reviewed by Sher, Sports Science & Nutrition Specialist · Editorial policy