Glycemic load calculator: from GI to the effect of a real portion
The glycemic index (GI) ranks how quickly the carbohydrate in a food raises blood glucose, but it says nothing about how much of that carbohydrate you eat. This glycemic load calculator combines the two: glycemic load (GL) = GI × grams of available carbohydrate ÷ 100. Watermelon has a high GI of 76, yet a cup of it carries so little carbohydrate that its GL is low.
Pick one of 62 common foods with a published average GI, choose a portion such as “1 cup cooked” or “1 medium”, and the available carbohydrate is filled in from USDA data — or type your own GI and carbs from a pack. Add foods to a meal to see the total GL and the meal’s carbohydrate-weighted GI. It works as a glycemic index calculator for mixed meals too.
How to use the Glycemic Load Calculator
- Choose Pick a food and select it from the list, or switch to Enter my own GI.
- Set the amount and portion; the available carbohydrate (carbs minus fibre) appears in grams. Overwrite it with the figure from your pack if you have one.
- Read the GL, its band (low, medium or high) and the working line.
- Press Add to meal for each food on the plate to get the meal GL and meal GI.
- Open the reference table at the bottom to compare the GI of all 62 foods.
Glycemic Load Calculator features
Published GI values
Average GI of 62 foods from the international GI tables (Atkinson, Foster-Powell & Brand-Miller, Diabetes Care 2008), with the standard error.
Real portions
Available carbohydrate comes from USDA FoodData Central for household portions — cups, slices, medium fruit — or grams.
Meal maths
Meal GL is the sum of each food’s GL; meal GI is the average GI weighted by each food’s carbohydrate.
Clear bands
GI low ≤ 55, medium 56–69, high ≥ 70; GL low ≤ 10, medium 11–19, high ≥ 20.
Your own values
Enter a GI from a study or a product’s certified GI and the carbs from its label.
How to calculate glycemic load
Glycemic load = GI × available carbohydrate in grams ÷ 100. Available carbohydrate means the carbohydrate your body digests — total carbohydrate minus dietary fibre. On US labels “Total Carbohydrate” includes fibre, so subtract it; UK and EU labels already list fibre separately.
Worked example. One cup of boiled white rice (158 g) has about 43.6 g of available carbohydrate (USDA). With a GI of 73: 73 × 43.6 ÷ 100 = 31.8, a high GL. A medium apple (200 g, 25.4 g available carbs, GI 36) gives 9.1, a low GL. Eaten together, the meal GL is about 41 and the meal GI is (73 × 43.6 + 36 × 25.4) ÷ 69 ≈ 59.
GI and GL bands
These cut-offs are the ones used with the international GI tables and by the University of Sydney’s GI research group. Some researchers also describe a total daily GL under about 80 as low and over 120 as high.
| Measure | Low | Medium | High |
|---|---|---|---|
| Glycemic index (glucose = 100) | 55 or less | 56–69 | 70 or more |
| Glycemic load per serving | 10 or less | 11–19 | 20 or more |
Limits of GI and GL
- GI is measured in a lab on a standard portion eaten alone; fat, protein, fibre and acid in a meal slow absorption, so mixed-meal GI is an estimate.
- Ripeness, variety, cooking time and cooling change GI — al dente pasta and parboiled rice are lower than soft-cooked versions.
- Individual glucose responses differ. A blood sugar log shows how you respond.
- Low GI does not mean healthy: chocolate and ice cream are low because of their fat. Look at the whole diet, including fibre and the net carbs you eat.
Glycemic Load Calculator FAQ
What is the difference between glycemic index and glycemic load?
GI compares how fast a fixed amount of carbohydrate raises blood glucose; GL also accounts for how much carbohydrate a portion contains. GL is the better guide to a real serving.
How do I calculate the glycemic load of a meal?
Work out each food’s GL (GI × available carbs ÷ 100) and add them. The glycemic load calculator does this when you press Add to meal, and also shows the carbohydrate-weighted meal GI.
What is a good glycemic load per day?
There is no official target. Studies often describe a daily GL under about 80 as low and above 120 as high. If you manage diabetes, follow the carbohydrate plan your care team gives you.
Where do the GI values come from?
From Table 1 of the International Tables of Glycemic Index and Glycemic Load Values: 2008 (Diabetes Care), which averages studies from several laboratories. For foods not listed, use a value from a published study or a certified product GI.
Is this glycemic index calculator suitable for diabetes?
It is for information and learning only — not a diagnosis or treatment plan. Talk to your doctor or dietitian, and check your own glucose readings, before changing food or medicine.