Daily fiber needs
How Much Fiber Do You Need Per Day?
Adults need 25 to 38 g of fiber a day depending on age and sex, or 30 g under UK advice. Most people eat about half that.
25–38 g
US adults: 38 g for men and 25 g for women aged 19 to 50; 30 g and 21 g from age 51. That works out to 14 g for every 1,000 calories you eat.
Your number in 5 seconds
Your US target: 28 g of fiber a day (14 g per 1,000 calories).
US recommendations by age and sex
These are the Adequate Intakes set by the National Academies and used by the Dietary Guidelines for Americans.
| Age | Male (g/day) | Female (g/day) |
|---|---|---|
| Children 1–3 | 19 | 19 |
| Children 4–8 | 25 | 25 |
| 9–13 | 31 | 26 |
| 14–18 | 38 | 26 |
| 19–30 | 38 | 25 |
| 31–50 | 38 | 25 |
| 51–70 | 30 | 21 |
| 71+ | 30 | 21 |
| Pregnancy | – | 28 |
| Breastfeeding | – | 29 |
UK recommendations
The UK’s Scientific Advisory Committee on Nutrition set one adult target of 30 g a day in 2015. The NHS uses the same figures.
| Age | Fiber (g/day) |
|---|---|
| 2–5 years | 15 |
| 5–11 years | 20 |
| 11–16 years | 25 |
| 16 and over | 30 |
Note that UK and US labels measure fiber the same way today (the AOAC method), so the numbers are directly comparable.
Other guidelines
- European Union (EFSA): 25 g a day for adults is enough for normal bowel function.
- World Health Organization: at least 25 g a day of naturally occurring fiber for adults.
- The research case for more: a large 2019 review in The Lancet found the biggest benefits at 25 to 29 g a day, with signs that even more may help further.
The gap: what people actually eat
American adults average about 15 to 17 g a day, and UK adults about 20 g. That means a typical man in the US eats less than half his target. A single cup of cooked lentils (15.6 g) roughly doubles a low-fiber day.
What 30 g looks like
| Food | Serving | Fiber |
|---|---|---|
| Rolled oats, dry | 1/2 cup (40 g) | 4 g |
| Raspberries | 1 cup (123 g) | 8 g |
| Black beans, cooked | 1 cup (172 g) | 15 g |
| Broccoli, cooked | 1 cup (156 g) | 5.1 g |
| Apple, with skin | 1 medium (182 g) | 4.4 g |
Total: 36.5 g. See full days in our meal plans.
FAQ
How much fiber should a woman eat per day?
US guidelines recommend 25 g a day for women aged 19 to 50 and 21 g after 50. During pregnancy the target is 28 g, and 29 g while breastfeeding. The UK recommends 30 g for all adults.
How much fiber should a man eat per day?
US guidelines recommend 38 g a day for men aged 19 to 50 and 30 g after 50. The UK recommends 30 g.
How much fiber do most people actually eat?
Average intake in the US is about 15 to 17 g a day, and in the UK about 20 g. More than 90% of adults fall short of the recommendation.
How much fiber is too much?
There is no official upper limit for fiber from food. Many people feel uncomfortable above about 50 to 70 g a day, especially if they increase quickly or do not drink enough water. Fiber supplements in large doses can also interfere with absorption of some medicines.
Why does the US use 14 g per 1,000 calories?
The US target comes from studies showing heart disease protection at about 14 g of fiber for every 1,000 calories eaten. The age and sex targets are that ratio applied to typical calorie needs.
Sources
- National Academies. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (2005).
- USDA and HHS. Dietary Guidelines for Americans, 2020–2025.
- SACN. Carbohydrates and Health (2015).
- NHS. How to get more fibre into your diet.
- Reynolds A, et al. Carbohydrate quality and human health: a series of systematic reviews and meta-analyses. The Lancet, 2019.
- EFSA. Scientific Opinion on Dietary Reference Values for carbohydrates and dietary fibre (2010).