Fiber calculator
Find out how much fiber you really need each day. Enter your details below for a personalized recommendation backed by USDA and Institute of Medicine guidelines.
We estimate 1,798 calories/day. Override if you know yours.
Your recommended daily fiber
The average American eats only 15g of fiber per day.
You need 25g, 67% more than the average.
What 25g of fiber looks like
Here's one way to hit your daily target with real food
1 cup black beans (cooked)
15g1 medium pear
5.5g1 oz almonds (23 nuts)
3.5gTrack your fiber intake with Grove
You know the goal. Now hit it. Grove lets you search real foods, log your fiber, and build a daily habit. On iPhone, iOS 18.0 or later.
How to use this calculator
- Enter your age, or drag the slider.
- Pick your biological sex.
- Pick the activity level closest to a normal week.
- If you know how many calories you eat in a day, enter that too. If you don't, the calculator estimates it.
- Read your daily fiber goal in grams. It updates as you change each answer.
There is no signup and nothing you enter is saved.
How we calculate your fiber goal
Our calculator combines two evidence-based approaches to give you the most accurate fiber target possible.
Method 1: IOM Adequate Intake
The Institute of Medicine (IOM) established Adequate Intake (AI) levels for fiber based on the amount associated with the lowest risk of cardiovascular disease in large epidemiological studies. For adults 19-50, that's 25 grams per day for women and 38 grams per day for men. Adults over 50 have slightly lower targets (21g and 30g respectively), reflecting typical decreases in caloric intake with age.
Method 2: 14 grams per 1,000 calories
The Dietary Guidelines for Americans recommend 14 grams of fiber for every 1,000 calories consumed. This scales your fiber needs to your actual energy intake. We estimate your daily calories with the Mifflin-St Jeor equation (the most accurate predictive equation for resting metabolic rate), then adjust for your activity level. You can also enter your own calorie intake if you already know it.
Your personalized recommendation
We take the higher of the two methods as your recommended daily fiber intake. This ensures your target accounts for both the population-level research behind the IOM guidelines and your individual caloric needs.
Sources: Institute of Medicine Dietary Reference Intakes, USDA Dietary Guidelines for Americans, USDA What We Eat in America (NHANES), and Reynolds et al., The Lancet, 2019.
Daily fiber intake by age and sex
If you only want the number, here it is. These are the Institute of Medicine Adequate Intake levels the calculator starts from, in grams of fiber per day.
For toddlers, pregnancy and breastfeeding, see the full daily fiber by age chart.
| Age | Women and girls | Men and boys |
|---|---|---|
| 4 to 8 | 25g | 25g |
| 9 to 13 | 26g | 31g |
| 14 to 18 | 26g | 38g |
| 19 to 50 | 25g | 38g |
| 51 and over | 21g | 30g |
How to calculate your fiber intake by hand
Take the calories you eat in a day, divide by 1,000, and multiply by 14. At 2,000 calories that is 2 x 14 = 28 grams. At 2,500 calories it is 2.5 x 14 = 35 grams.
Then compare that with your row in the table and use the higher number. A 30-year-old woman eating 2,000 calories gets 28 grams from the calorie rule and 25 grams from the table, so her goal is 28 grams. The calculator above does the same thing, and estimates your calories for you if you do not know them.
How to work out what one food or drink adds
Once you know your goal, any Nutrition Facts label tells you how far one food gets you. It takes three steps.
- Find Dietary Fiber on the label. It sits under Total Carbohydrate. Read the grams, and skip the percentage for now.
- Check the serving size at the top. If the can or bag holds two servings and you had all of it, double the grams. The FDA's label guide puts it this way: two servings is two times the nutrients shown.
- Divide those grams by your daily goal.
Take a fiber soda that lists 9 grams of fiber per can. Against a 25 gram goal, one can is 9 / 25 = 36% of your day, and you have 16 grams left to find in food. Against a 38 gram goal the same can is 24%.
| Fiber on the label | 25g goal | 28g goal | 38g goal |
|---|---|---|---|
| 3g | 12% | 11% | 8% |
| 5g | 20% | 18% | 13% |
| 9g | 36% | 32% | 24% |
The percentage printed on the label uses one number for everyone. The FDA sets the Daily Value for fiber at 28 grams, so the label matches the 28g column above. If your goal is different, go by the grams.
Frequently asked questions
- The Institute of Medicine recommends 25 grams per day for women and 38 grams per day for men ages 19-50. For adults over 50, the recommendation drops to 21g for women and 30g for men. An alternative guideline from the USDA is 14 grams per 1,000 calories consumed. Our calculator uses the higher of these two methods to give you a personalized target.
- The Dietary Guidelines for Americans recommend consuming 14 grams of fiber for every 1,000 calories you eat. This calorie-based approach adjusts your fiber target to match your energy needs. For example, someone eating 2,500 calories per day would need 35 grams of fiber. Our calculator estimates your calorie needs using the Mifflin-St Jeor equation, then applies this rule.
- The calculator uses two evidence-based methods. First, it looks up the Institute of Medicine (IOM) Adequate Intake for your age and sex. Second, it estimates your daily calorie needs using the Mifflin-St Jeor equation (based on your age, sex, and activity level) and applies the USDA guideline of 14g per 1,000 calories. Your recommendation is the higher of these two values, giving you a personalized target that accounts for both demographic guidelines and your actual energy expenditure.
- Men typically need more fiber than women because they generally consume more calories. Since fiber recommendations are tied to caloric intake (14g per 1,000 calories), higher calorie consumption means a higher fiber target. The IOM set the Adequate Intake at 38g for men and 25g for women based on studies showing the level of fiber intake associated with the lowest risk of cardiovascular disease.
- The IOM recommends 25 grams per day for children ages 4-8 (both sexes). For ages 9-13, boys need 31g and girls need 26g. Teens ages 14-18 need 38g (boys) or 26g (girls). These recommendations are based on adequate intake levels that support healthy digestion and cardiovascular development.
- Fiber is good for you, but if you ramp up too fast you will feel bloated and gassy. There is no formal upper limit from the IOM. Most experts suggest adding about 5 grams per week and drinking plenty of water. If you are starting near 15g per day (the American average), give yourself 2 to 4 weeks to reach your target comfortably.
- Low fiber intake is linked to higher rates of cardiovascular disease, type 2 diabetes, colorectal cancer, and digestive issues like constipation and diverticular disease. The USDA has classified fiber as a 'nutrient of public health concern' because roughly 93% of Americans fall short of the recommended daily intake.
- Divide your daily calories by 1,000 and multiply by 14. Someone eating 2,000 calories a day needs 28 grams of fiber. Then check the Institute of Medicine number for your age and sex (25 grams for women and 38 grams for men ages 19-50) and use the higher of the two. The calculator on this page does both steps for you.
- No. A fiber intake calculator tells you your daily goal in grams. A fiber tracker adds up what you actually eat each day so you can see how close you got. Use the calculator once to find your number, then track your food against it.
- Find Dietary Fiber on the Nutrition Facts label and read the grams per serving. Multiply by the number of servings you had, then divide by your daily goal. A fiber soda that lists 9 grams per can is 9 divided by 25, or 36% of a 25 gram goal. Two cans is 18 grams.
- The FDA bases the % Daily Value for fiber on 28 grams a day for everyone. If your goal is 25 grams or 38 grams, the percentage on the label will be a little off for you. Use the grams on the label and divide by your own goal instead.
How much fiber should I eat per day?+
What is the 14 grams per 1,000 calories rule?+
How does this fiber calculator work?+
Why do men need more fiber than women?+
How much fiber do children need?+
Is it possible to eat too much fiber?+
What happens if I don't eat enough fiber?+
How do I calculate my daily fiber intake?+
Is a fiber intake calculator the same as a fiber tracker?+
How do I calculate how much fiber a drink or packaged food adds to my day?+
Why does the % Daily Value for fiber on a label not match my goal?+
Not sure where you stand?
Take the 2-minute Fiber Intake Quiz to estimate how much fiber you currently eat and get personalized tips to close the gap.
Learn more about fiber
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Track your fiber intake with Grove
Search real foods, hit your daily goal, and build a gut health habit. On iPhone, iOS 18.0 or later.