Glycemic Index Calculator
Look up the glycemic index (GI) and calculate the glycemic load (GL) of over 100 common foods. Use the meal builder to see the total glycemic load of your entire meal.
Look Up GI & Calculate GL
| Food | GI | Carbs | GL | |
|---|---|---|---|---|
| Total (0 items) | -- | 0g | 0 |
Meal GL is the sum of individual food GLs. A meal GL under 10 is low, 11-19 is medium, 20+ is high.
What Is the Glycemic Index?
The GI was developed by Dr. David Jenkins at the University of Toronto in 1981 and has since been tested on thousands of foods. The largest database is maintained by the University of Sydney, which has published GI values for over 4,000 food items. The values in this calculator are sourced from their research and cross-referenced with data from Oregon State University's Linus Pauling Institute.
Medical Disclaimer: This tool provides general educational estimates. Always consult your prescribing physician or healthcare provider before making medication changes or interpreting results from population-based models.
Contents
GI and GL Classification
| Classification | Glycemic Index (GI) | Glycemic Load (GL) | Blood Sugar Effect |
|---|---|---|---|
| Low | 55 or less | 10 or less | Slow, gradual rise |
| Medium | 56–69 | 11–19 | Moderate rise |
| High | 70 or more | 20 or more | Rapid spike and crash |
Why Glycemic Load Matters More
GI tells you how fast a food raises blood sugar, but not how much. Watermelon has a high GI of 76, but a cup contains only 11g of carbs — giving it a GL of just 8 (low). Conversely, spaghetti has a moderate GI of 46, but a cup has 44g of carbs — giving it a GL of 20 (high). For real-world dietary decisions, GL is the better metric because it accounts for both speed and quantity of blood sugar impact.
Factors That Affect Glycemic Index
The GI of a food is not fixed — it varies based on several factors:
- Cooking method: Boiling pasta al dente (GI 46) vs. overcooking it (GI 58+). Baking a potato (GI 85) vs. boiling (GI 78). More cooking generally increases GI by breaking down starch.
- Ripeness: A green banana has a GI around 30; a ripe yellow banana is 51; an overripe brown banana can reach 62. Ripening converts resistant starch to sugar.
- Processing: Whole rolled oats (GI 55) vs. instant oatmeal (GI 79). Whole wheat bread (GI 69) vs. pumpernickel (GI 41). More processing = higher GI.
- Food combinations: Adding fat, protein, or acid (vinegar, lemon juice) to a meal slows digestion and lowers the effective GI. A slice of white bread alone (GI 75) has a lower effective GI when eaten with peanut butter.
- Variety: Jasmine rice (GI 89) vs. basmati rice (GI 58) vs. brown rice (GI 50). Same food, very different GI values depending on the starch structure.
- Individual variation: The same food can produce different blood sugar responses in different people, depending on gut microbiome, insulin sensitivity, and genetics. GI values are population averages.
How to Use GI in Your Diet
Practical Tips
- Swap, don't eliminate. Replace white rice (GI 73) with basmati (GI 58) or brown rice (GI 50). Replace white bread (GI 75) with sourdough (GI 54) or pumpernickel (GI 41).
- Combine high-GI foods with protein and fat. A baked potato (GI 85) eaten with cheese and chicken has a much lower effective glycemic impact than eaten alone.
- Focus on GL, not just GI. A small portion of a high-GI food may have a lower glycemic impact than a large portion of a medium-GI food.
- Keep daily GL moderate. A daily GL under 80 is considered low; over 120 is high. Most health benefits come from keeping GL moderate rather than eliminating all high-GI foods.
- Eat whole, unprocessed foods. As a general rule, less processing means lower GI. Whole fruit is better than fruit juice; steel-cut oats are better than instant.
Frequently Asked Questions
What is a good glycemic index number?
A GI of 55 or below is classified as "low" and is generally best for blood sugar management. Most fruits, vegetables, legumes, and whole grains fall in this range. However, GI alone doesn't tell the whole story — glycemic load (which accounts for portion size) is a better guide for food choices. A low-GL food (GL under 10) has minimal blood sugar impact regardless of its GI value.
Is the glycemic index useful for diabetes?
Yes. The American Diabetes Association recognizes GI as a useful tool alongside carb counting. Research shows that low-GI diets improve HbA1c (long-term blood sugar) by 0.3-0.5% in people with type 2 diabetes — comparable to some medications. However, GI should be used as one factor among many, including total carbohydrate intake, fiber content, and overall diet quality. Always work with your healthcare team.
Does the glycemic index help with weight loss?
Evidence is mixed. Low-GI foods tend to be more satiating (they keep you full longer), which can help reduce overall calorie intake. A 2018 Cochrane review found that low-GI diets produced slightly more weight loss than high-GI diets, but the difference was small. The main benefit is likely indirect: choosing low-GI foods usually means eating more whole foods, fiber, and fewer processed carbohydrates.
Why does watermelon have a high GI but low GL?
Watermelon is 92% water. The small amount of sugar it contains (about 11g per cup) is absorbed quickly — hence a high GI of 76. But because there's so little sugar per serving, the actual blood sugar impact is small: GL = (76 × 11) ÷ 100 = 8.4 (low). This is precisely why GL is more practical than GI for dietary decisions. You'd have to eat over 4 cups of watermelon to reach a high GL.
Can I lower the GI of my meal?
Yes. Adding protein (meat, eggs, cheese), fat (olive oil, nuts, avocado), or acid (vinegar, lemon juice) to a high-GI food slows digestion and reduces the blood sugar spike. Studies show that 2 tablespoons of vinegar before a high-GI meal can reduce the post-meal blood sugar response by 20-30%. Cooking pasta al dente instead of soft also lowers its GI by 10+ points.
Sources
- Jenkins, D.J. et al. (1981). "Glycemic index of foods: a physiological basis for carbohydrate exchange." American Journal of Clinical Nutrition, 34(3), 362-366.
- Atkinson, F.S. et al. (2008). "International Tables of Glycemic Index and Glycemic Load Values: 2008." Diabetes Care, 31(12), 2281-2283.
- Atkinson, F.S. et al. (2021). "International Tables of Glycemic Index and Glycemic Load Values 2021." American Journal of Clinical Nutrition, 114(5), 1625-1632.
- Linus Pauling Institute, Oregon State University. "Glycemic Index and Glycemic Load." Micronutrient Information Center, reviewed 2023.
- Brand-Miller, J. et al. "The New Glucose Revolution." University of Sydney GI Research Group.
- American Diabetes Association. "Glycemic Index and Diabetes." Diabetes.org, 2024.