Glycemic Load Calculator
Glycemic Index Alone Doesn't Tell You What You're Eating
Glycemic index measures how quickly a carbohydrate raises blood sugar per gram of carbohydrate — but it says nothing about portion size. Watermelon has a high glycemic index yet contains relatively little carbohydrate per serving, while a large bowl of a moderate-index grain can deliver a much bigger blood sugar impact simply through volume. Glycemic load corrects for this by factoring in the actual amount of carbohydrate in a real serving.
The Formula
Dividing by 100 rescales the product so that a food with a glycemic index of 100 (pure glucose, the reference standard) and 100 grams of carbohydrate in a serving would land at a glycemic load of 100 — an extreme case used to anchor the scale.
Classification Bands
| Glycemic load | Category |
|---|---|
| 10 or below | Low |
| 11 to 19 | Medium |
| 20 or above | High |
How Portion Size Changes the Load
For a food with a fixed glycemic index of 70, changing only the serving's carbohydrate content:
| Carbs per serving | Glycemic load | Category |
|---|---|---|
| 10 g | 7.0 | Low |
| 20 g | 14.0 | Medium |
| 30 g | 21.0 | High |
| 45 g | 31.5 | High |
| 60 g | 42.0 | High |
Computed directly with the formula above. The same glycemic index moves through all three categories purely by changing the portion — which is exactly the limitation of using glycemic index alone.
Why This Matters for Blood Sugar Management
- Comparing real servings — two foods with similar glycemic index can have very different glycemic loads once actual serving sizes are accounted for.
- Portion control strategy — since load scales linearly with carbohydrate amount, reducing portion size directly reduces load even without switching foods.
- Meal planning for blood sugar — totaling glycemic load across a meal's components gives a more complete picture than looking at any single ingredient's index in isolation.
How to Use This Calculator
- Enter the food's Glycemic Index (0 to 110).
- Enter Carbohydrates per Serving in grams.
- Select Calculate for the glycemic load and its Low/Medium/High classification.
Related Calculations
To see how carbohydrate totals fit into your broader daily targets, use the Macronutrient Ratio Calculator. For fiber intake, which also affects blood sugar response, see the Fiber Intake Calculator.