Carb Counter Calculator

Pick a food, enter what you are actually eating in grams, and this gives you total carbohydrate, fibre and net carbs for that portion, then shows it against the daily target you are working to.

Net carbs, and why the number is smaller than the label says

Net Carbs = Total Carbohydrates − Dietary Fiber

Fibre is a carbohydrate your small intestine cannot break down, so it passes through without raising blood glucose. That is the whole idea behind net carbs. It matters more for some foods than others: 100g of white rice has almost no fibre, so total and net are nearly the same, while 100g of black beans loses more than a third of its carbohydrate to fibre. The gap is what makes beans and lentils behave so differently from bread despite similar-looking labels.

A third term appears on packaged low-carb products: sugar alcohols, which are partially absorbed and conventionally halved before subtracting. Erythritol is the exception and can be subtracted in full. None of the whole foods in the list below contain them, so the calculator does not ask, but you will need the adjustment for anything from a protein bar wrapper.

Carbohydrate per 100g, and what it looks like as a portion

Figures are USDA reference values for the food alone. Cooking method barely moves them, but anything added afterwards does: a tablespoon of ketchup is another 5g.

Worked example

A cup of cooked black beans, 170g. Total carbs = 24 × 1.7 = 40.8g. Fibre = 8.7 × 1.7 = 14.8g. Net carbs = 26.0g.

On a 50g keto day that single cup is over half your allowance. On the ADA’s 45 to 60g per meal guidance it fits comfortably inside one meal with room for something alongside it.

Daily carb targets by goal. These are general starting points, not prescriptions, and your healthcare team’s number beats any of them.

• Very low carb / keto: 20 to 50g per day
• Moderate restriction: 100 to 130g per day
• ADA general guidance: 45 to 60g per meal
• Athletes with diabetes: 150 to 250g per day

If you are counting carbs for insulin

Carb counting exists mainly because insulin dosing depends on it. Your endocrinologist sets an Insulin-to-Carb Ratio (ICR), meaning one unit covers a certain number of grams, commonly 15 to start. The dose for a meal is net carbs divided by that ratio.

This calculator deliberately stops short of that arithmetic. An ICR is personal, it changes with time of day, illness and activity, and a page that cannot know any of those has no business producing a number you might inject. Use it to get the carb figure right, then apply your own ratio.

Important: never adjust insulin doses based on a website. This is a learning and planning tool.