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. The ADA’s starting point of 45 to 60g a meal counts total carbohydrate, so there the cup counts as 40.8g: at 60g that leaves room for a small side, and at 45g almost none.

Carb targets, and which carbs each one counts. These are general starting points, not prescriptions, and your healthcare team’s number beats any of them. The calculator compares each target with the figure it is written in.

• Very low carb / keto: 20 to 50g a day, usually counted as net carbs.
• Low carb: under 130g a day of total carbohydrate. That line is the definition used in the 2015 Feinman consensus on carbohydrate restriction, and 130g is also the US RDA, set from how much glucose the brain uses.
• ADA starting point: 45 to 60g of total carbohydrate a meal, a long-standing figure that a diabetes educator then moves up or down for you.
• Food label Daily Value: 275g of total carbohydrate a day, the FDA’s reference for a 2,000 kcal diet.

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 the carbohydrate divided by that ratio. Whether that means total carbs or total minus some of the fibre is your clinic’s call, so use whichever they taught you; the panel shows both.

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.