Glycemic Load Calculator
Based on Net Carbs.
Blood Glucose Response Chart
The Glycemic Load (GL) calculator is a tool that estimates a specific food’s effect on blood sugar levels by combining its Glycemic Index (GI: how quickly carbohydrates raise blood sugar) with the amount of digestible carbohydrates per serving.
It helps people, especially those managing diabetes or diets, predict the impact of foods on their glucose levels more accurately than the Glycemic Index alone.
The GL Calculation Formula:
Glycemic Load (GL) = (Glycemic Index (GI) × Digestible Carbohydrates (g) per serving) ÷ 100
To calculate the Glycemic Load (GL): Multiply the Glycemic Index (GI) by the digestible carbohydrates in a serving, then divide by 100.
Below the calculator, an Interactive Blood Glucose Chart displays the glycemic impact based on the calculated Glycemic Load for your food. This chart adjusts for metabolic health profiles, such as normal, pre-diabetic, or diabetic states, helping you visualize how different foods might influence your blood glucose based on your condition.
To calculate Glycemic Load (GL), you need two variables:
- Glycemic Index (GI) of the food
- Digestible Carbohydrates in serving (Total Carbohydrates minus dietary fiber)
Glycemic Index (GI)
The Glycemic Index (GI) is a scale from 0 to 100 that measures how quickly a carbohydrate-containing food raises blood sugar levels after consumption.
High-GI foods, like white bread or sugary snacks, cause rapid spikes, while low-GI foods, such as lentils or most vegetables, lead to a slower, more gradual increase. The GI scale compares foods to pure glucose (GI = 100), offering insight into how different carbohydrates affect energy levels and insulin response.
However, Glycemic Index alone does not tell the full story.
Read more: Glycemic Index: Simple Science, Complex Controversy
While the Glycemic Index (GI) measures how quickly blood sugar rises after consuming a fixed amount of carbohydrates, it doesn’t reflect the total rise, which depends on the digestible carbohydrates consumed. This is where Glycemic Load (GL) comes in.
Glycemic Load provides a more complete measure of a food’s blood sugar impact by combining GI with the digestible carbohydrates per serving.
For example, watermelon has a high GI of 72, but with only 7.2g grams of digestible carbohydrates per 100 grams, its GL is low (approximately 5.18), meaning it has a minimal overall effect on blood sugar.
By combining GI and GL, you can make informed dietary choices, managing both the speed and extent of blood sugar changes to support energy stability, weight management, and diabetes control.
Why Portion Size Matters?
Portion size determines the amount of digestible carbohydrates you eat, which the Glycemic Load (GL) calculation uses. GL multiplies a food’s Glycemic Index (GI) by the digestible carbohydrates in a serving, then divides by 100. A small portion of high-GI watermelon (GI 72) has a low GL due to its few digestible carbohydrates (e.g., 7.2g per 100g serving, GL 5.18), while a large serving of low-GI pasta can have a higher GL with more digestible carbohydrates. It’s the serving size that makes GL a better gauge of blood sugar impact than GI alone.
The GL formula relies on digestible carbohydrates, those that affect blood glucose, excluding dietary fiber, which doesn’t significantly raise blood sugar. This focus ensures GL accurately reflects a food’s glycemic effect based on both GI and the amount consumed.
Digestible Carbohydrates and Glycemic Load
Digestible carbohydrates (net carbs) are a crucial input in any Glycemic Load calculator, as they represent the actual amount of carbohydrate that affects blood sugar — making the calculation accurate and reflective of real metabolic impact.
Digestible carbohydrates, also called net carbs or available carbohydrates, are the total carbohydrates in a food minus its dietary fiber and, for some sugar alcohols like erythritol, their non-glycemic portion, since these components don’t significantly raise blood sugar. In the Glycemic Load (GL) calculation, you multiply a food’s Glycemic Index (GI) by its net carbohydrates per serving and divide by 100. This approach ensures a precise measure of the food’s impact on blood glucose levels.
For example, if a food contains 25g total carbohydrates, including 6g fiber and 4g erythritol (a sugar alcohol with negligible glycemic effect), the digestible carbohydrates are 15g (25 - 6 - 4).
Using this 15g in the GL formula provides an accurate reflection of its blood sugar effect.
This distinction is particularly valuable for low-carb or keto diets, where fiber-rich foods like nuts or vegetables may appear high in total carbohydrates but have a lower digestible carbohydrate content, making GL an effective tool for managing insulin and energy levels without inflating carbohydrate impact.
Glycemic Load Calculation
The Glycemic Load (GL) calculation shows how much a specific serving of food affects your blood sugar by combining its Glycemic Index (GI) with the grams of digestible carbohydrates in that serving. The formula is simple: multiply the GI (a number from 0 to 100 showing how quickly carbs raise blood sugar) by the digestible carbohydrates (total carbs minus fiber) in a serving, then divide by 100.
For example, if a food has a GI of 50 and a 20g serving contains 20g of digestible carbs (after subtracting fiber), the GL is (50 × 20) ÷ 100 = 10. A GL below 10 is low, 11-19 is medium, and 20 or higher is high.
Using digestible carbohydrates ensures accuracy, especially for high-fiber foods, providing a clear picture of how your blood sugar responds to what’s on your plate.