The calculation runs in your browser; no data is sent or stored. The result is for information only and does not replace assessment by your doctor.
What does the macronutrient calculator show?
The calculator starts from your energy needs and divides them into the three macronutrients, that is carbohydrate, protein and fat. The energy figure comes from the Mifflin-St Jeor equation, which estimates resting expenditure from weight, height, age and sex, then multiplies it by an activity factor [1]. The headline result is the number of grams of carbohydrate per day, because that is the number you work with at each meal if you count carbohydrate.
Below it come protein, in grams and in grams per kilogram of body weight, then fat and total energy. Most people usually take in between 1 and 1.5 g per kilogram per day, and in chronic kidney disease the recommendation drops to 0.8 g per kilogram [2]. If you only want the energy, without the split, you will find it at the calorie calculator. The figure does not apply to competitive athletes, to pregnant women, or to people with other diseases that change metabolism. The Mifflin-St Jeor equation is validated in adults and cannot be used in children.
How much carbohydrate per day is right in diabetes?
There is no single figure. No ideal macronutrient distribution could be established for everyone with diabetes [2]. The plan is built on each person's habits, preferences and goals [2].
The consistent finding is that reducing carbohydrate has the most evidence for lowering blood glucose. That is why the calculator gives you three patterns instead of one figure, and why choosing between them stays a conversation with your doctor or dietitian.
Why are there three distribution patterns and not just one?
Because the same amount of energy can be split in many ways, and the difference shows up in blood glucose. The first pattern, with half the energy from carbohydrate, is close to ordinary eating. The second drops to 40%, the third to 30% and shifts the energy toward fat.
The last two fall outside the ranges considered acceptable for the general population, where carbohydrate sits between 45% and 65% of energy. They are still patterns in current use in diabetes. The calculator shows all three so you can see how much the grams change, not to recommend one of them.
How do I get from grams per day to the food on my plate?
The grams per day are divided across the meals you actually eat. The calculator shows a simple split across three main meals, which is a starting point, not a rule. If you also have snacks, you take their carbohydrate out of the main meals.
The next step is translating grams into food. For that, you use the carbohydrate content of usual portions and the nutrition label. If you are on insulin, the grams at a meal connect to your insulin dose through the insulin-to-carbohydrate ratio.