About glycemic index and glycemic load
The glycemic index (GI) ranks how quickly a carbohydrate-containing food raises blood glucose compared with a reference food, on a 0-100+ scale where pure glucose is set to 100 (white bread is a common alternate reference, scoring around 70 on the glucose scale). GI alone does not account for portion size, so nutrition science also uses glycemic load (GL), which multiplies the GI by the grams of available carbohydrate in an actual serving and divides by 100: GL = GI x carbs (g) / 100. This calculator applies that standard formula.
How the calculation works
- Enter the food's glycemic index as published in a GI table or food source - the glucose-referenced scale is most common; choose the bread-referenced option if that is what your source used.
- Enter the available carbohydrate per serving in grams - total carbohydrate minus fiber, since fiber has minimal effect on blood glucose.
- Enter how many of those servings you are evaluating; the calculator scales the glycemic load to match.
Reading the classification
Based on the widely cited International Tables of Glycemic Index and Glycemic Load, a GI of 55 or under is classified low, 56 to 69 is medium, and 70 or above is high on the glucose-referenced scale. Glycemic load uses its own bands: 10 or under is low, 11 to 19 is medium, and 20 or above is high. A food can carry a high GI yet a low GL if a typical serving has little carbohydrate - watermelon is the textbook example.
When to consult a professional
This calculator performs the standard GI/GL arithmetic only; it is not a meal plan or medical advice. Anyone managing diabetes, prediabetes, or another condition affected by blood glucose should review dietary changes with a physician or registered dietitian.