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Fiber Calculator

Find out how many grams of fiber to aim for each day, based on the calories you eat and your age and sex.

Last updated September 24, 2026

Your details

Units
Sex
Weight
Height

Your daily fiber target

26 g

That’s 14 g for every 1,000 calories you eat, based on about 1,830 calories a day.

Fiber guidelines for you
GuidelineGrams a day
14 g per 1,000 calories26 g
Adequate intake (women 19–50)25 g

Add fiber slowly and drink water with it to avoid stomach upset.

Not medical advice. If you have kidney disease, diabetes, or take prescription medication, talk to your doctor or a registered dietitian before changing your protein intake. Read our full disclaimer.

How this fiber calculator works

The Institute of Medicine set fiber needs at 14 grams for every 1,000 calories. The U.S. Dietary Guidelines use the same number. So the more you eat, the more fiber you need.

Here is what the calculator does:

  1. It estimates your daily calories with the Mifflin-St Jeor equation, using your weight, height, age, and sex.
  2. It multiplies that by your activity level to get your maintenance calories.
  3. It multiplies your calories by 14 g per 1,000.

For example, if you eat about 2,000 calories a day, your target is 28 g of fiber.

Adequate intake by age and sex

The calculator also shows the adequate intake for your group. These are fixed numbers from the same report:

GroupFiber per day
Men 19 to 5038 g
Men 51+30 g
Women 19 to 5025 g
Women 51+21 g

Your two numbers will often be close. If they differ, either one is a fine goal. Most people eat much less than both.

How to get more fiber

  • Swap white bread, rice, and pasta for whole grain versions.
  • Add beans or lentils to soups, salads, and bowls.
  • Eat fruit with the skin on instead of drinking juice.
  • Snack on nuts, seeds, or raw vegetables.
  • Start your day with oats or a high-fiber cereal.

Go slowly. Add a few grams a week and drink plenty of water. This gives your gut time to adjust and helps avoid bloating.

Fiber, protein, and fullness

Fiber and protein both help you feel full, which is useful if you are trying to lose weight. Beans, lentils, and edamame give you both. Use our protein calculator to set your protein goal, and read our guide on how much fiber per day for food ideas and serving sizes.

If you have a digestive condition, diabetes, or kidney disease, talk to your doctor or a registered dietitian before making big changes to your diet.

Frequently asked questions

How much fiber per day do I need?

U.S. guidelines suggest 14 grams of fiber for every 1,000 calories you eat. As a set number, the adequate intake is 38 g for men 19 to 50, 30 g for men 51 and older, 25 g for women 19 to 50, and 21 g for women 51 and older.

How does this fiber intake calculator work?

It estimates your daily calories with the Mifflin-St Jeor equation and your activity level. Then it multiplies by 14 g per 1,000 calories. It also shows the adequate intake for your age and sex so you can compare.

Can you eat too much fiber?

Adding a lot of fiber quickly can cause gas, bloating, or cramps. Add it slowly over a few weeks and drink water with it. If you have a bowel condition such as IBS or Crohn's disease, talk to your doctor or a registered dietitian about the right amount for you.

What foods are high in fiber?

Beans, lentils, whole grains, oats, vegetables, fruit with the skin on, nuts, and seeds are all good sources. Many high-protein plant foods like beans and lentils give you fiber and protein at the same time.

Sources

  1. Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. National Academies Press, 2005.
  2. U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2020-2025.
  3. Mifflin MD, et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990.