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How Much Fiber Per Day? Targets by Age and Sex
Adults need 21 to 38 grams of fiber a day, depending on age and sex. Here's your number, where it comes from, and how to get there without the bloat.
The Short Answer
Most adults should aim for 21 to 38 grams of fiber a day. Where you land depends on your age and sex: younger men need the most, women over 50 the least.
Most of us fall well short. On average, Americans eat about 16 grams a day.
Want your exact number? The Fiber Goal Calculator works it out in under a minute.
Daily Fiber Targets by Age and Sex
These are the official U.S. targets, set by the National Academies. They’re called Adequate Intakes.
| Age | Women | Men |
|---|---|---|
| 19 to 50 | 25 g a day | 38 g a day |
| 51 and up | 21 g a day | 30 g a day |
The targets drop after 50 because people over 50 eat fewer calories on average, and the targets are tied to calories. More on that next.
This page covers adults. Kids and teens have their own targets, and if you’re pregnant or breastfeeding, ask your doctor or midwife what’s right for you.
The 14 Grams per 1,000 Calories Rule
All four numbers come from one rule: 14 grams of fiber for every 1,000 calories you eat. The National Academies multiplied that by how many calories a typical person in each group eats.
That means you can work out a personal number if you know roughly how many calories you eat. At 2,000 calories a day, it’s 28 grams. Bigger appetite, bigger number. The calculator can do this for you if you enter your calories.
How Much Fiber Most Americans Get
About 16 grams a day, according to MedlinePlus, the U.S. National Library of Medicine’s health site. That leaves a big gap:
| Target | Gap from 16 g |
|---|---|
| 21 g | 5 g |
| 25 g | 9 g |
| 30 g | 14 g |
| 38 g | 22 g |
The good news: a gap of 5 to 10 grams is a couple of foods. Half a cup of cooked lentils has about 7.8 grams. A cup of raspberries has about 8. See the high-fiber foods list for 44 more, with grams for each.
How to Ramp Up Without the Bloat
Don’t close the gap overnight. A lot of fiber at once can bring gas, bloating and cramps. MedlinePlus says that usually settles once the bacteria in your gut get used to it, and that adding fiber slowly helps.
The plan that works:
- Go over a few weeks. MedlinePlus says to add fiber gradually over a few weeks.
- Add one food at a time. Eat it most days for a week before adding the next.
- Drink enough. MedlinePlus suggests about 8 glasses of water or other no-calorie drinks a day. Water helps fiber pass through.
The free 30-Day Fiber Ramp turns this into a day-by-day plan.
Can You Eat Too Much Fiber?
You can eat it too fast, which is where most of the discomfort comes from.
There’s one more thing to know. MedlinePlus notes that too much fiber may get in the way of absorbing some minerals, like iron, zinc, magnesium and calcium. It adds that this usually isn’t much of a concern, because high-fiber foods tend to be rich in those minerals.
For most people, the real issue is too little fiber, not too much. If you have a digestive condition or your doctor has told you to limit fiber, follow their advice over any general target, this one included.
Find Your Number With the Calculator
The Fiber Goal Calculator asks your age, sex and, if you like, your calories. It gives you a daily target, shows how far you are from it, and spreads the gap over a few weeks.
Get the 30-Day Fiber Ramp
A free 30-day plan that adds fiber a little at a time, so your gut can keep up. Plus the odd email with easy fiber wins.
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Sources
- Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (2005) , Institute of Medicine, The National Academies Press
- Fiber , MedlinePlus Medical Encyclopedia, U.S. National Library of Medicine
