Glycemic Index & Glycemic Load Calculator
Turn a food's glycemic index (GI) and carbohydrate content into its glycemic load (GL) — a better measure of how much a real-world serving will raise blood glucose.
GI of the food on the glucose = 100 scale.
Total carbs minus fibre, for the portion you eat.
How to Use This Calculator
- Enter the food's glycemic index on the glucose = 100 scale (use the reference table below or a published GI list).
- Enter the available carbs per serving — total carbohydrate minus fibre — for the portion you actually eat.
- Read the glycemic load and its low / medium / high band.
GL reflects a real serving's glucose impact better than GI alone. It guides food choice and is a complement to — not a replacement for — carbohydrate counting.
Glycemic Index vs Glycemic Load
The glycemic index ranks a carbohydrate food by how quickly it raises blood glucose compared with pure glucose (GI 100). But GI ignores portion size. The glycemic load fixes that by scaling GI to the actual grams of carbohydrate in a serving:
Example: watermelon has a high GI (~72) but few carbs per serving (~8 g) → (72 × 8) ÷ 100 = GL ≈ 6 (low).
GI and GL Reference Bands
| Category | Glycemic Index | Glycemic Load (per serving) |
|---|---|---|
| Low | ≤ 55 | ≤ 10 |
| Medium | 56–69 | 11–19 |
| High | ≥ 70 | ≥ 20 |
Lower-GL meals tend to produce smaller, steadier glucose rises, which can support insulin sensitivity over time.
Glycemic Index of Common Foods
Approximate GI values on the glucose = 100 scale (they vary by variety, ripeness and cooking):
| Food | Approx. GI | Band |
|---|---|---|
| White bread | ~75 | High |
| White rice | ~73 | High |
| Boiled potato | ~78 | High |
| Watermelon | ~76 | High |
| Banana (ripe) | ~51 | Low–medium |
| Rolled oats | ~55 | Low |
| Apple | ~36 | Low |
| Lentils / chickpeas | ~28–32 | Low |
| Whole milk | ~39 | Low |
| Peanuts | ~14 | Low |
How to lower a meal's glycemic load
Pair carbohydrate with protein, healthy fat or fibre; choose whole, less-processed grains over refined ones; keep carb portions modest; add acidity such as vinegar or lemon; and note that cooking and cooling starchy foods like potato, rice and pasta forms resistant starch that lowers the effective GL.
Frequently Asked Questions
How do you calculate glycemic load?
Multiply the food's glycemic index by the grams of available carbohydrate in your serving, then divide by 100. For example, a food with GI 64 and 30 g carbs has a GL of (64 × 30) ÷ 100 = 19.2.
What is the difference between GI and GL?
GI rates how fast a carbohydrate raises glucose, regardless of amount. GL accounts for both speed (GI) and quantity (carbs per serving), so it better reflects a realistic portion's effect on blood sugar.
What is a good glycemic load?
Per serving, a GL of 10 or under is considered low, 11–19 medium, and 20 or more high. Lower-GL choices generally cause gentler blood-glucose rises, but overall diet quality and total carbs still matter.
Does glycemic load replace carb counting for insulin?
No. For mealtime insulin, carb counting with your insulin-to-carb ratio is the standard. GL is a complementary guide to food choice. See our insulin-to-carb ratio calculator for dosing.
Which foods have a low glycemic index?
Most non-starchy vegetables, legumes (lentils, chickpeas, beans), most whole fruits such as apples and berries, rolled oats, dairy, and nuts are low GI (55 or under). Highly processed grains, white bread and rice, and many starchy foods like potatoes tend to be high GI.
Does cooking or ripeness change a food's glycemic index?
Yes. A riper banana has a higher GI than a green one, and longer-cooked or mashed starches raise GI versus firm, al-dente versions. Cooking then cooling potatoes, rice or pasta forms resistant starch that lowers the effective GI, even if you reheat them gently.
Sources
- Atkinson FS, Foster-Powell K, Brand-Miller JC. International tables of glycemic index and glycemic load values. Diabetes Care.
- Harvard T.H. Chan School of Public Health. Carbohydrates and blood sugar — glycemic index and load.
Last reviewed: June 2025