Glycemic Load Calculator
Glycemic Load = GI × carb grams / 100. Low/med/high categorisation.
Overview
Glycemic load (GL) is a more practical cousin of the glycemic index (GI). Where GI ranks a food by how sharply 50 grams of its carbohydrate raises blood sugar, GL adjusts for the actual portion size, so a watermelon slice (high GI but low carb content) ends up with a modest GL rather than a frightening one. This makes glycemic load the better tool for everyday meal planning.
Tracking glycemic load is useful for people managing type 2 diabetes, insulin resistance, polycystic ovary syndrome, or simply trying to avoid energy crashes. A meal centred on low-GL foods tends to produce a gentler, more sustained rise in blood glucose, which can support better satiety and mood across the afternoon.
How it works
The formula is GL = (GI × carbohydrate_grams) / 100, where GI is the food's glycemic index (a number from 0 to 100 referenced to pure glucose). The result is a unitless score that is then classified — typically a GL below 10 is "low," 11 to 19 is "medium," and 20 or above is "high." Adding GL across the foods in a meal gives a rough total, with daily totals under 100 considered low and above 200 considered high.
Because GL is a multiplication of intensity (GI) and quantity (grams), you can lower a meal's GL either by swapping for a lower-GI food or by shrinking the portion. Mixing in protein, fat, and fibre slows digestion and effectively lowers the realised glycemic response further, though the GL number itself does not capture that.
Examples
- A 120 g serving of watermelon with GI 76 and 9 g carbs:
(76 × 9) / 100≈ 6.8 — low. - A medium baked potato with GI 85 and 35 g carbs:
(85 × 35) / 100≈ 29.8 — high. - A 150 g serving of lentils with GI 28 and 18 g carbs:
(28 × 18) / 100≈ 5 — low. - A bowl of cornflakes with GI 81 and 26 g carbs:
(81 × 26) / 100≈ 21 — high; oats at GI 55 and 27 g carbs give about 15 — medium.
FAQ
Is GL better than GI?
For everyday decisions, yes — it accounts for portion size. GI is still useful when comparing equal-carb servings of similar foods.
Does cooking change GL?
Yes. Cooking pasta al dente versus soft, or boiling potatoes versus baking them, can shift GI by 10 to 20 points.
Do I need to count GL like calories?
Most people benefit from awareness rather than strict tracking. Aim for low-to-medium-GL choices most of the time.
Why is fibre not in the formula?
Carb grams in the equation should exclude fibre (i.e. net carbs). Soluble fibre also blunts the real-world glycemic response in ways the formula does not show.