How to Count Carbs

Medically Reviewed by Michael Dansinger, MD on March 18, 2023
3 min read

Carbohydrates are a great source of energy for your body, but they affect your blood sugar too. If you have diabetes, keep track of how many you eat with a few simple tricks.

Know your carbs. It's a lot more than just pasta and bread. All starchy foods, sugars, fruit, milk, and yogurt are rich in carbs, too. Make sure you count them all, not just the obvious ones.

Put together a meal plan. Figure out the amount of carbs, protein, and fat you can eat at meals and snacks throughout the day to keep your blood sugar levels steady. Most adults with diabetes aim for 45-60 grams of carbs per meal and 15-20 grams per snack. That number may go up or down, depending on how active you are and the medicines you take, so check with your doctor or a registered dietitian.

Look at labels. They make counting carbs easy. Find the "Total Carbohydrate" number listed on a package's "Nutrition Facts" panel. Then, check the serving size and confirm the amount you can eat. Repeat this step with other foods you plan to eat. When you add all the grams of carbs, the total should stay within your meal budget.

Starch, fruit, or milk = 15. Fresh foods don't come with a label. You may have to guess the number of carbs they have. A good rule of thumb: Each serving of fruit, milk, or starch has about 15 grams. Vegetables don't have a lot, so you can eat more of them. Two or three servings of veggies usually equal 15 grams of carbs.

Pay attention to portion sizes. The size of one serving depends on the type of food. For instance, one small (4-ounce) piece of fresh fruit, 1/3 cup of pasta or rice, and 1/2 cup of beans are each one serving. Buy a pocket guide that lists carb counts and portion sizes. Or download an app on your smartphone. Measuring cups and a food scale when you eat at home will help you be accurate.

Adjust your insulin. Your doses may change, depending on the amount of carbs you ate at a meal and the difference between your target blood sugar level and your actual reading. You'll need to know your "insulin-to-carbohydrate ratio," or the number of carbs one unit of insulin will cover. Generally, one unit of fast-acting insulin covers 12-15 grams of carbohydrates.

Your body can also be more sensitive to insulin changes throughout the day. Stress or how much you exercise also has an impact. It's important to work out a plan with your doctor for how to change your treatment if you need to.

Make healthy choices. Carb counting focuses on the number of them you eat at every meal, not what types. Still, pick healthy options when you can. Foods and drinks with added sugar are often high in calories and low on nutrients. Healthy carbs like whole grains, fruits, and veggies will give you energy and the vitamins, minerals, and fiber that can help control your weight.