Fiber Intake Calculator

1. Enter your age. Fiber recommendations change at different life stages. The AI (Adequate Intake) decreases after age 50 as calorie intake typically drops.
2. Select your gender. Men and women have different fiber targets. The USDA recommends 38 grams per day for men aged 19 to 50 and 25 grams per day for women in the same range.
3. Enter your daily calorie intake. The DRI (Dietary Reference Intake) method sets fiber at 14 grams per 1,000 calories consumed, so someone eating 2,500 calories needs 35 grams of fiber. If you are unsure of your calorie intake, use 2,000 for an average adult.
4. Read your two targets. The DRI-based target scales with your calorie intake. The USDA Adequate Intake value is based on age and gender alone. Aim to meet whichever is higher.
5. Use the food table. Scroll to the reference table to see which foods are the best fiber sources and whether they are mainly soluble or insoluble. A cup of navy beans provides more fiber than most people eat in an entire day.

Dietary fiber recommendations come from two primary sources: the USDA Dietary Reference Intakes (DRI) and the Adequate Intake (AI) values set by the Institute of Medicine. Both are based on epidemiological data linking fiber intake to cardiovascular disease risk.

DRI Method (14g per 1,000 kcal)

Daily Fiber Target = (Daily Calories / 1000) × 14

Example: 2,200 calorie diet
Fiber target = (2200 / 1000) × 14 = 30.8 grams/day

This method adjusts fiber intake proportionally to energy intake. It is useful because people who eat more calories also have larger bowel volumes and benefit from proportionally more fiber.

USDA Adequate Intake Values

Soluble vs. Insoluble Fiber

Total fiber consists of two types with different effects. About 25 to 30% of your fiber target should come from soluble fiber, which dissolves in water to form a gel. Soluble fiber slows digestion, lowers LDL cholesterol, and helps regulate blood sugar. Good sources include oats, beans, apples, and psyllium husk.

The remaining 70 to 75% should come from insoluble fiber, which does not dissolve and passes through the gut largely intact. It adds bulk to stool, speeds transit time, and reduces constipation risk. Good sources include whole wheat, bran, nuts, and most vegetables.