By Zencalcy Editorial TeamLast reviewed About us
This calculator reports a daily fibre target based on age and sex using widely cited dietary reference intakes. Fibre supports digestion, feeds gut bacteria and can help with cholesterol and blood glucose. The target is a reference intake, not a minimum you must hit perfectly every day.
Daily fibre target by age and sex.
Men ≤50: 38 g · Men >50: 30 g Women ≤50: 25 g · Women >50: 21 g
These values follow common adult dietary reference intakes for total fibre. The alternative guide of 14 g per 1000 kcal gives 28 g at a 2000 kcal reference intake. Increase fibre slowly and drink enough fluid, since a sudden jump can cause bloating or cramping.
| Symbol | Meaning |
|---|---|
| age | Age in years; the target changes after 50. |
| sex | Used to select the reference intake. |
| fibre | Daily total fibre target in grams. |
| kcal guide | 14 g of fibre per 1000 kcal, shown at 2000 kcal. |
A woman aged 50 or younger has a reference intake of 25 g of fibre per day. At the 2000 kcal guide of 14 g per 1000 kcal, the equivalent figure is 28 g. The two references are close but not identical, so treat them as a range and build up from your current intake.
Most people fall short of fibre targets, and the gap is usually a matter of food patterns rather than knowledge. A useful strategy is to add one fibre-rich food at each meal instead of overhauling the whole diet: oats or whole-grain toast at breakfast, beans or lentils at lunch, and an extra vegetable or fruit at dinner. Fibre comes in soluble and insoluble forms, and different plant foods provide different mixes, so variety matters more than chasing a single number. Increasing fibre quickly can cause temporary gas and bloating as gut bacteria adapt, so raise intake over a few weeks and keep fluid intake up. If you have a condition such as inflammatory bowel disease or a history of bowel obstruction, ask a clinician before making a large change.
Continue with the BMR Calculator (Mifflin-St Jeor), Harris-Benedict Calculator, or the Katch-McArdle Calculator — or browse more dietary tools and all health calculators.
Also see the Calorie Calculator, TDEE Calculator and the Macro Calculator.
Common adult reference intakes are 38 g for men aged 50 or younger, 30 g for men over 50, 25 g for women aged 50 or younger and 21 g for women over 50. Individual needs vary with energy intake and health conditions.
Energy and nutrient estimates are population guidance, not personal prescriptions. Actual needs vary with body composition, medical conditions, medication, pregnancy and activity. Values are rounded and should be discussed with a registered dietitian or clinician when used to plan treatment.
Reference material used to build and check this calculator:
Last reviewed: September 2026. See how we build and check every tool on the about page.
Content updated: September 2026