FibrePlan

Fibre Intake Calculator

IOM daily fibre recommendations by age and gender.

Age (years)

Daily fibre target

38 g

Institute of Medicine recommendations

What you entered

Gender: maleAge: 30

1
IOM recommendation by age & gender
male, age under 50= 38 g/day

Result

Daily fibre target: 38 g

For a 30-year-old male, the IOM recommends 38 g of fibre per day.

IOM daily fibre targets by age and sex

The Institute of Medicine sets one fibre target per sex that steps down at age 50, so every age inside a band shares the same number. These are the exact grams the calculator returns.

Age (years)	Male target (g/day)	Female target (g/day)
19	38	25
25	38	25
30	38	25
40	38	25
49	38	25
50	30	21
55	30	21
65	30	21
75	30	21

The only break point is age 50: under 50 it is 38 g for men and 25 g for women, from 50 onward 30 g and 21 g. The step down tracks lower average calorie intake with age, since the IOM guideline is calibrated at roughly 14 g of fibre per 1,000 kcal. Most adults eat only 15 to 17 g a day. Increase intake gradually and with extra fluid, or the change causes bloating.

The most under-consumed nutrient in most diets

Most adults fall well short of daily fibre recommendations — this calculator gives the specific age- and sex-adjusted target set by the Institute of Medicine so you have a concrete number to aim for.

Why fibre needs shift with age

Recommended fibre intake generally decreases slightly with age due to lower average calorie needs, since the IOM guideline is partly calibrated per 1,000 calories consumed.

Frequently asked questions

How much fibre should I eat per day?

IOM recommendations: men 19–50 need 38g/day, men 51+ need 30g. Women 19–50 need 25g/day, women 51+ need 21g. Most adults only eat 15–17g — roughly half the recommended amount. The average Western diet is significantly fibre-deficient.

What are the best sources of fibre?

High-fibre foods per serving: lentils (15g per cup), black beans (15g), artichoke (10g), raspberries (8g), pear (6g), oats (4g per cup), broccoli (5g per cup), chia seeds (10g per oz). A mix of soluble fibre (oats, beans) and insoluble fibre (whole grains, vegetables) is ideal.

What happens if you don't eat enough fibre?

Low fibre intake is linked to constipation, higher cholesterol, blood sugar spikes after meals, and increased risk of colorectal cancer, heart disease, and type 2 diabetes. Fibre feeds beneficial gut bacteria, slows digestion for steadier blood sugar, and adds bulk that helps waste move through the intestines.