How much fiber should I eat per day?

Adequate Intake is about 38 g/day for men under 51 and 30 g/day after, and 25 g/day for women under 51 and 21 g/day after. A simple rule is 14 g of fiber per 1,000 calories you eat.

How is the fiber target calculated?

Two ways: from calories at 14 g per 1,000 kcal (the U.S. Dietary Guidelines rule), or from the Adequate Intake (AI) values set by age and sex in the Dietary Reference Intakes.

What's the difference between soluble and insoluble fiber?

Soluble fiber (oats, beans, apples) dissolves in water and can help lower cholesterol and steady blood sugar. Insoluble fiber (whole grains, vegetables, wheat bran) adds bulk and aids regularity. Most plant foods contain both, so a varied diet covers them.

Can you eat too much fiber?

Going well above your target too quickly can cause bloating, gas and cramping, and very high intakes may reduce absorption of some minerals. Increase fiber gradually and drink plenty of fluids.

Does more fiber help with weight loss?

Fiber-rich foods are filling and slow digestion, which can curb appetite and support weight management. It is a helpful tool, but total calories still drive weight change.

Fiber Intake Calculator

This fiber intake calculator estimates how many grams of dietary fiber to aim for each day — either from your calorie intake (14 g per 1,000 kcal) or from the Adequate Intake values for your age and sex.

How it works

There are two common ways to set a daily fiber goal. The calorie method follows the U.S. Dietary Guidelines rule of 14 g of fiber per 1,000 calories consumed, so the more you eat, the more fiber you need. The age & sex method uses the Adequate Intake (AI) values from the Dietary Reference Intakes, which step down after age 50 as energy needs fall. Both give a target in grams per day; pick whichever inputs you have.

Worked example

Someone eating a 2,000 kcal diet needs 2,000 ÷ 1,000 × 14 = 28 g/day. Using the age & sex method instead, a 30-year-old man has an Adequate Intake of 38 g/day, while a 30-year-old woman is at 25 g/day.

Adequate Intake by age and sex

Daily fiber Adequate Intake (AI) values:

Group	Age	Fiber (g/day)
Men	Under 51	38 g
Men	51 and over	30 g
Women	Under 51	25 g
Women	51 and over	21 g

Calorie-based rule: 14 g of fiber per 1,000 kcal consumed (U.S. Dietary Guidelines).

Frequently asked questions

How much fiber should I eat per day?: Adequate Intake is about 38 g/day for men under 51 and 30 g/day after, and 25 g/day for women under 51 and 21 g/day after. A simple rule is 14 g of fiber per 1,000 calories you eat.
How is the fiber target calculated?: Two ways: from calories at 14 g per 1,000 kcal (the U.S. Dietary Guidelines rule), or from the Adequate Intake (AI) values set by age and sex in the Dietary Reference Intakes.
What's the difference between soluble and insoluble fiber?: Soluble fiber (oats, beans, apples) dissolves in water and can help lower cholesterol and steady blood sugar. Insoluble fiber (whole grains, vegetables, wheat bran) adds bulk and aids regularity. Most plant foods contain both, so a varied diet covers them.
Can you eat too much fiber?: Going well above your target too quickly can cause bloating, gas and cramping, and very high intakes may reduce absorption of some minerals. Increase fiber gradually and drink plenty of fluids.
Does more fiber help with weight loss?: Fiber-rich foods are filling and slow digestion, which can curb appetite and support weight management. It is a helpful tool, but total calories still drive weight change.

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Disclaimer. This is general guidance, not medical or nutritional advice. Increase fiber gradually and drink plenty of fluids, and consult a healthcare professional about your individual needs.