Enter a food's glycemic index and the carbs and fiber from its label to get its glycemic load. Free, no sign-up.
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Fill in the fields above and select "Calculate glycemic load" to see your result.
Can You Calculate Glycemic Index From a Food Label?
No. There is no formula for glycemic index. GI is measured in people: a small group of volunteers eats a portion of the food containing 50 grams of available carbohydrate, and their blood glucose is tracked for two hours and compared with their response to the same amount of pure glucose. The average of those responses is the food's GI. A nutrition label never lists it, and nothing printed on the panel can be plugged into an equation to produce it. Our guide to glycemic index vs. glycemic load covers the testing method in more detail.
That leaves three practical ways to fill in the GI box:
- Published GI tables. The University of Sydney GI database and Harvard Health both list tested values for common foods. Our own GI vs. GL chart of 15 common foods pulls the same values together with servings and GL. Results shift with variety, ripeness, and cooking, so treat a table value as typical rather than exact.
- The food picker in the calculator. It fills in a typical GI for 15 common foods, shows where each number comes from, and links to our full breakdown of that food where we have one. It deliberately leaves the carbs blank: those should come from your own label or your actual serving.
- A label-reading app's estimate. For packaged and store-brand foods that don't appear in any table, an app can estimate GI from the product's carbohydrate, fiber, sugars, and ingredients. An estimate isn't a measured value; see how an AI glycemic index scanner arrives at its number for what that difference means.
Once you have a GI, the calculator handles the part that can be calculated: the glycemic load of the serving on your plate. You can also browse our food-by-food GI guides for the full numbers on staples like rice, oats, and potatoes.
What Glycemic Load Actually Means
Glycemic index ranks how fast a food's carbohydrates raise blood glucose, on a scale that runs from 0 to roughly 110. Glycemic load scales that by how much carbohydrate is in a real serving, because people eat servings, not lab portions. That makes GL the more useful number at the table.
Watermelon is the classic example. Its GI is high, which makes it look like a food to avoid, but a cup of cubes carries very little carbohydrate because the fruit is mostly water, so its glycemic load per serving is low. GI tells you how fast a food's carbs hit; GL tells you how much that matters for the amount you eat. For a full side-by-side comparison, see our complete guide to glycemic index vs. glycemic load.
How to Calculate Glycemic Load From a Nutrition Label
Glycemic load has one formula, and it isn't proprietary. Anyone can run it with a nutrition label and a GI value.
GL = (GI × available carbohydrate in grams) ÷ 100
The term that trips people up is "available carbohydrate." On a U.S. nutrition facts panel, fiber is already included in the Total Carbohydrate figure, but fiber isn't digested into glucose, so it doesn't drive blood sugar the way starches and sugars do. Available (sometimes called "net" or "glycemic") carbohydrate is Total Carbohydrate minus Dietary Fiber, and minus sugar alcohols where the label lists them separately.
Worked example: a medium result
Take a serving with 30 g total carbohydrate and 5 g dietary fiber, and a glycemic index of 60:
- Total carbohydrate: 30 g
- Dietary fiber: 5 g
- Available carbohydrate: 30 − 5 = 25 g
- Glycemic index: 60
- Glycemic load: (60 × 25) ÷ 100 = 15 (Medium)
Worked example: a high result from a big portion
White rice has a GI of about 73. A restaurant-size serving of a cup and a half, cooked, carries roughly 67 g of available carbohydrate:
- Available carbohydrate: about 67 g
- Glycemic index: 73
- Glycemic load: (73 × 67) ÷ 100 ≈ 49 (High)
A half-cup of the same rice, at about 22 g of available carbohydrate, works out to a GL of about 16, back in the Medium band. And for a Low result, go back to watermelon: a GI of about 80 but only about 11 g of carbohydrate in a cup, so 80 × 11 ÷ 100 ≈ 9. Our white rice breakdown walks through the portion math in more detail.
Reading Your Result: What Low, Medium, and High GL Mean
A glycemic load number is only useful if you know what to do with it. The standard reference bands, per serving:
- Low: 10 or under
- Medium: 11 to 19
- High: 20 or more
A few things worth keeping in mind when you use them:
- GL is most useful for comparing two foods or two products against each other, not as a number to hit in isolation.
- Portion size matters. GL scales with the serving, so doubling a serving roughly doubles its glycemic load, even though the food's GI hasn't changed at all.
- A high-GI food can still land in the Low or Medium band if the actual serving is small. That's the watermelon effect from earlier.
Using the calculator to compare two foods
The bands are most useful side by side. Say you're choosing between rice and quinoa for dinner. Pick "White rice, cooked" in the calculator and enter about 44 g of carbohydrate for a cooked cup: the result is a GL of about 32, High. Now pick "Quinoa, cooked" and enter the roughly 34 g of available carbohydrate in a cooked cup: a GL of about 18, Medium. Same portion, a meaningfully smaller load. Our quinoa breakdown covers why it works as a direct swap.
These are general reference bands, not personal targets, and GL is a decision-support estimate, not a clinical measurement. If you're managing diabetes, prediabetes, or a pregnancy-related condition like gestational diabetes, follow your clinician's specific guidance over any generic band shown here.
The Easiest Way to Check GI and GL Without Memorizing Charts
Standing in the aisle with a package in your hand, the fastest route to an answer depends on what you're holding:
- Whole foods and staples: pick the food in the calculator above, or look up its GI in a published table, then add the carbs for your portion.
- Packaged foods with a known GI: type the GI into the calculator and copy the carbs and fiber straight off the label.
- Packaged foods with no published GI: point a label-reading app at the nutrition panel. Glycemic Genius uses Google Gemini to read total carbohydrate, fiber, sugars, and ingredients off the label and returns an estimated GI and GL for that specific product, with no chart lookup and no manual math.
None of these is universally "best." If you already know the GI, the calculator is all you need. An app earns its keep on store-brand and packaged items that don't appear on any chart, where you'd otherwise be guessing which entry is close enough.
Don't want to type in the numbers?
Glycemic Genius reads the label and estimates GI and GL for you. Free, 10 scans per month, no credit card required.
Is There a Free Way to Check Glycemic Index and Load?
Yes. The calculator at the top of this page is free, with no sign-up and no download. Use it as many times as you want.
If you check a lot of packaged foods and would rather skip the manual entry, Glycemic Genius, the app this site is built around, also has a free tier: 10 scans per month, no credit card required. Premium removes that monthly limit for $4.99/month or $44.99/year. It's a convenience upgrade for people who scan often, not a gate on the answer itself. For how it compares with other label and barcode apps, see our full glycemic index app comparison.