Free Fiber Calculator

How much fiber do you need per day? Enter your age and sex for the National Academies Adequate Intake. Add calories if you know them, and you also get the 14g per 1,000 kcal figure the tables are built from.

Your age

Sex

FemaleMale

Pregnancy or breastfeeding

NeitherPregnantBreastfeeding

Daily calories (optional)

If you know your calorie intake, the calculator also shows 14g of fiber per 1,000 kcal, which is the rule the age and sex targets are built from.

Your daily fiber target

25g

The adult female Adequate Intake is 25g per day, equal to 14g of fiber per 1,000 kcal of estimated energy need.

The FDA Daily Value printed on food labels is 28g, based on a 2,000 calorie diet. Most adults in the United States eat about half of what they need.

Set this number as your daily goal in Fibey and log foods against it.

This is general nutrition guidance, not a medical diagnosis. If you have IBS, inflammatory bowel disease, a bowel stricture, or have been given a specific fiber prescription, follow your clinician. Increase fiber over days and weeks, not overnight, and drink water as you go.

How much fiber per day, in plain numbers

The National Academies set an Adequate Intake of 14 grams of fiber for every 1,000 calories. That produces the familiar adult numbers: 25g for women 19 to 50, 38g for men 19 to 50, then 21g and 30g after 51 because estimated calorie needs fall. The FDA Daily Value on the Nutrition Facts label is 28g, which is the same 14g per 1,000 kcal rule applied to a 2,000 calorie diet.

Almost nobody hits those numbers. The Dietary Guidelines for Americans call fiber a dietary component of public health concern: more than 90% of women and 97% of men do not meet recommended intakes. A 2015 Academy of Nutrition and Dietetics position paper put mean US intake at about 17g a day, with only 5% of people meeting the Adequate Intake.

That gap is the whole reason to calculate a target instead of guessing. A 2019 Lancet review of carbohydrate quality found people eating 25g to 29g of fiber a day had lower rates of coronary heart disease, type 2 diabetes and colorectal cancer than people eating much less, with possible extra benefit above 30g. The calculator gives you a personal number. Closing even half the gap from a typical 16g to 17g day is a meaningful change.

Set this target in Fibey

Once you have a gram number, the useful next step is logging against it. Fibey is a dedicated fiber tracker: set your daily goal, add foods as you eat, and see the day add up without opening a full calorie diary.

Free to download on iOS. No account required.

Common questions

How much fiber do I need per day?

Adult women need 25g per day through age 50 and 21g after that. Adult men need 38g through age 50 and 30g after that. Those figures are Adequate Intake values from the National Academies, built from 14g of fiber per 1,000 calories. The number on food labels is 28g, which is the FDA Daily Value for a 2,000 calorie diet.

Why is the target lower after 50?

Estimated calorie needs fall with age, and the Adequate Intake is 14g of fiber per 1,000 calories. The gram target drops because the calorie estimate drops, not because fiber becomes less important.

Can I eat too much fiber?

There is no official upper limit. The practical problem is jumping too fast. Going from a typical 16g day to 30g overnight commonly causes bloating and cramping. Increase by a few grams at a time and drink water. People with bowel disease or who have been told to follow a specific fiber prescription should follow that, not this calculator.

Does soluble or insoluble fiber matter more?

Both. Soluble fiber (oats, beans, apples, chia) forms a gel and is the type most associated with cholesterol and blood-sugar effects. Insoluble fiber (wheat bran, vegetable skins, whole grains) adds bulk. The Adequate Intake is for total fiber from food, so a mix of plants covers both without you having to count them separately.