What is glycemic load and how is it different from glycemic index?

Glycemic index (GI) ranks how quickly a fixed amount of carbohydrate from a food raises blood glucose relative to pure glucose (GI 100). Glycemic load (GL) goes one step further: it multiplies the GI by the actual grams of available carbohydrate in your real-world serving, then divides by 100. A food can have a high GI but a low GL if the serving is small — watermelon is the classic example (GI 76, but a typical 120g portion contains only about 8g of carbs, giving a GL of around 6).

What is the formula for glycemic load?

GL = (GI x available carbohydrates in grams) divided by 100. Available carbohydrates means total carbohydrates minus fibre (net carbs). For example, 150g of white rice (GI 73) contains roughly 28g of carbs per 100g, so the available carbs in that serving are 42g and the GL is (73 x 42) / 100 = 30.7.

What counts as a low, medium or high glycemic load?

For a single food or meal, GL 10 or below is low, 11-19 is medium, and 20 or above is high. For an entire day, a low-GL diet typically stays below 80-100, a moderate diet stays below 120, and a high-GL diet exceeds 120. These thresholds come from the original Harvard research by Salmeron and colleagues (1997) and are used in most nutrition guidelines worldwide.

Which foods have the lowest glycemic load per typical serving?

Non-starchy vegetables, legumes, and most whole fruits score lowest. Boiled lentils (GL around 4 per 150g), chickpeas (GL 7), apples (GL 5) and strawberries (GL 2) are excellent examples. The key insight is that fibre-rich, minimally processed foods deliver carbohydrate slowly, keeping both GI and net carbs low.

Can I use this to plan a low-GL diet?

Yes. Build each meal using the calculator, then add the meal totals across the day. Aim for individual meals of GL 10 or below and a daily total below 100 for a strict low-GL approach. Swapping white rice (GL 31 per 150g) for basmati (GL 23) or pearled barley (GL 11) at one meal already makes a meaningful difference.

Are the GI values in this calculator reliable?

All GI values come from the International Tables of Glycemic Index and Glycemic Load compiled by Foster-Powell, Holt and Brand-Miller (2002, updated 2021) — the same reference used in clinical research and diabetes management guidelines. Real-world GI can vary by +-5-10 points depending on ripeness, cooking method, and individual physiology, so treat results as a guide rather than a precise prescription.

Glycemic Load Calculator

Understanding how much a meal will affect your blood sugar matters far more than whether a food simply has a “high” or “low” glycaemic index. That is the core insight behind glycemic load (GL): it combines the quality of the carbohydrate (captured by the GI) with the quantity you actually eat, producing a single number that predicts the real glucose impact of a serving.

This calculator covers more than 60 common foods — grains, bread, pasta, rice, vegetables, legumes, fruit, dairy, snacks and beverages — and lets you build a complete meal by stacking as many items as you like. Every component shows its individual GL in real time; the total updates automatically as you add or adjust servings.

How glycemic load is calculated

The formula is straightforward:

GL = (GI × available carbohydrates in grams) / 100

Available carbohydrates are the net carbs in your actual serving: (carbohydrates per 100g / 100) × serving weight in grams. So for 150g of white rice with 28g carbs per 100g:

Available carbs = (28 / 100) × 150 = 42g
GL = (73 × 42) / 100 = 30.7 — classified as High

The same 150g serving of pearled barley (GI 28, 22g carbs/100g):

Available carbs = (22 / 100) × 150 = 33g
GL = (28 × 33) / 100 = 9.2 — classified as Low

Same plate size, very different metabolic impact.

Worked example: a typical lunch

Suppose you eat a medium jacket potato (150g, GI 85), a side of baked beans (150g, GI 40) and a glass of orange juice (250ml, GI 50):

Food	GI	Available carbs	GL
Baked potato (150g)	85	30g	25.5
Baked beans (150g)	40	22.5g	9.0
Orange juice (250ml)	50	25g	12.5
Meal total	—	77.5g	47.0

Swap the jacket potato for a medium sweet potato (GI 63), the white juice for water, and add lentils instead of baked beans:

Food	GI	Available carbs	GL
Sweet potato (150g)	63	25.5g	16.1
Green lentils (150g)	25	18g	4.5
Meal total	—	43.5g	20.6

The revised lunch delivers less than half the glycemic load of the original, with more fibre and protein to boot.

The GL scale and daily targets

Per meal: GL ≤10 = Low, GL 11–19 = Medium, GL ≥20 = High
Per day: below 80–100 is considered a low-GL diet; below 120 is moderate; above 120 is high

Research by Jenkins, Brand-Miller and colleagues shows that low-GL diets are associated with improved insulin sensitivity, better long-term blood glucose control in type 2 diabetes, lower cardiovascular risk markers, and more stable appetite regulation compared with high-GL diets matched for total calories.

Practical tips for lowering meal GL

Choose pasta cooked al dente over overcooked; lower starch gelatinisation reduces GI by 10–15 points.
Add vinegar, lemon juice or acidic dressings to starchy meals — acidity slows gastric emptying and lowers GL.
Combine high-GI foods with protein, fat or fibre; these macronutrients blunt the glucose response.
Allow cooked potatoes and rice to cool before eating; cooling increases resistant starch, cutting effective GI by 20–25%.
Opt for whole fruit over juice — the fibre matrix dramatically reduces the rate of sugar absorption.