Fibre Intake Calculator
Estimate a daily fibre target based on your age and sex using commonly referenced nutrition intake guidelines.
Calculate Your Daily Fibre Target
Enter your details below to see an estimated daily fibre intake target.
This calculator is designed for adults aged 19 years and older.
Used to select the corresponding adult fibre reference intake.
Your fibre target will appear here
Complete the calculator to see your estimated daily fibre intake target.
If your current fibre intake is much lower, increasing it gradually and drinking adequate fluids may be more comfortable than making a large change all at once.
This result is a general nutrition reference, not an individual medical prescription. Individual requirements can differ.
What Does Your Fibre Target Mean?
Your result is an estimated daily reference intake for total dietary fibre. It provides a practical target for planning your overall eating pattern rather than an exact amount you must reach every day.
Individual needs can vary. The calculator uses adult reference intake values based on age and sex rather than attempting to prescribe a personalised medical or therapeutic diet.
Men Ages 19–50
The reference intake used by this calculator for adult men aged 19 through 50 is 38 grams of total fibre per day.
Men Ages 51+
The reference intake used by this calculator for adult men aged 51 and older is 30 grams of total fibre per day.
Women Ages 19–50
The reference intake used by this calculator for adult women aged 19 through 50 is 25 grams of total fibre per day.
Women Ages 51+
The reference intake used by this calculator for adult women aged 51 and older is 21 grams of total fibre per day.
You Don't Need to Hit the Exact Number
Your result is best viewed as a reference target rather than a pass-or-fail number. Fibre intake can naturally vary from one day to another depending on the foods and portions you eat.
Increase Fibre Gradually
If you currently eat relatively little fibre, increasing your intake gradually can be more comfortable than making a large change suddenly. Adequate fluid intake is also important as fibre intake increases.
Important: The values shown above apply to the adult groups included in this calculator. Fibre requirements differ for children and teenagers, and separate reference values apply during pregnancy and breastfeeding.
How Does the Fibre Intake Calculator Work?
The calculator matches your age and sex with the corresponding adult daily fibre reference used by the calculator. It does not estimate fibre from your body weight, height or activity level.
Enter Your Age
Age determines whether the calculator uses the adult 19–50 reference group or the reference group for adults aged 51 and older.
Select Sex for Estimation
The calculator uses the male or female adult reference value corresponding to the age group you entered.
See Your Reference Target
Your result is displayed in grams of total dietary fibre per day and should be treated as a general reference rather than an exact prescription.
Adult Fibre Reference Values Used
The calculator selects one of the following daily fibre values according to the information entered.
| Sex | Age | Daily Fibre Reference |
|---|---|---|
| Male | 19–50 years | 38 g/day |
| Male | 51+ years | 30 g/day |
| Female | 19–50 years | 25 g/day |
| Female | 51+ years | 21 g/day |
Why Isn't Body Weight Used?
This calculator is based on adult fibre reference values for age and sex. Unlike some nutrition calculations, these particular targets are not calculated directly from your height, weight or exercise level.
A Reference, Not a Prescription
Your actual needs and appropriate fibre intake can differ because of your diet, health, digestive tolerance and individual circumstances. Medical conditions may also affect what is appropriate for you.
Why Is Fibre Important?
Dietary fibre is the part of plant foods that is not completely broken down by human digestive enzymes. Different types of fibre behave differently in the digestive system, which is one reason eating a variety of fibre-rich foods is useful.
Supports Normal Bowel Function
Fibre contributes to stool bulk and can help support regular bowel function as part of an overall balanced diet with adequate fluid intake.
Supports Digestive Health
Some fibres are fermented by microorganisms in the large intestine and can provide substrates for members of the gut microbiota.
Can Help With Fullness
Fibre-rich foods can contribute to satiety and fullness, although the effect varies according to the food, type of fibre and overall meal.
Part of a Heart-Healthy Diet
Fibre-rich foods such as whole grains, legumes, vegetables, fruits, nuts and seeds can form part of an overall dietary pattern that supports cardiovascular health.
Soluble and Insoluble Fibre
Fibre is often described as soluble or insoluble, although individual fibres can have different properties and some do not fit neatly into only one category.
Soluble Fibre
Some soluble fibres dissolve or form gels in water and may be fermented in the colon. Sources include foods such as oats, barley, legumes, apples and citrus fruits.
Insoluble Fibre
Insoluble fibres generally do not dissolve in water and can contribute to stool bulk. Sources include foods such as wheat bran, whole grains, vegetables, nuts and seeds.
Reaching a daily fibre target does not tell the whole story about diet quality. A varied eating pattern containing vegetables, fruits, legumes, whole grains, nuts and seeds can provide fibre alongside vitamins, minerals and other nutrients.
High-Fibre Foods to Help Reach Your Target
Fibre is found naturally in plant foods including legumes, whole grains, vegetables, fruits, nuts and seeds. Combining several fibre-rich foods throughout the day can make your daily target easier to reach.
Beans, Lentils & Chickpeas
Fibre-Rich Fruits
Grains & Cereals
Fibre-Rich Vegetables
Nuts & Nut Foods
Fibre-Rich Seeds
Fibre Can Add Up Across the Day
You do not need to obtain your entire fibre target from one food or meal. Several moderate sources can contribute to your total intake.
Whole grains and fruit can provide fibre early in the day.
Combining plant foods can increase the fibre content of a meal.
A simple snack can make another contribution toward the day's total.
Beans, lentils or chickpeas can provide a substantial amount of dietary fibre.
Fibre content varies by food variety, serving size, preparation method and product. Check the nutrition information for a specific packaged food when you need a more precise value, and increase fibre gradually if your usual intake is much lower.
How to Increase Your Fibre Intake Gradually
If your current diet contains much less fibre than your estimated target, you do not need to make the entire change at once. Introducing additional fibre-rich foods gradually can give your digestive system time to adjust.
Start With One Change
Rather than changing every meal at once, begin by adding or replacing one food with a fibre-rich option and build from there.
Spread Fibre Across the Day
Include fibre-containing foods at several meals and snacks rather than trying to consume most of your daily fibre in one sitting.
Choose a Variety of Plant Foods
Whole grains, legumes, vegetables, fruits, nuts and seeds contain different types of fibre and can contribute to a varied eating pattern.
Pay Attention to How You Feel
A sudden increase in fibre can cause digestive discomfort for some people. Adjust the pace of change according to your tolerance.
Simple Ways to Add More Fibre
Small changes to foods you already eat can increase fibre intake without requiring a completely different diet.
Berries, oats, chia seeds or ground flaxseed can add fibre to breakfast foods you already enjoy.
Add vegetables, beans, lentils or chickpeas to meals, or choose whole-grain options where appropriate.
Fruit, nuts, seeds and some whole-grain foods can contribute additional fibre between meals.
Remember Fluids
Adequate fluid intake is important as dietary fibre intake increases. Your fluid needs vary with factors such as body size, activity, climate and overall diet.
Don't Rush a Large Increase
Increasing fibre substantially and suddenly can cause bloating, gas or changes in bowel habits for some people. A gradual increase may be more comfortable.
Some digestive or medical conditions may require different fibre advice. If you have been advised to follow a restricted-fibre diet, have persistent digestive symptoms, or are unsure what is appropriate for you, seek guidance from an appropriately qualified health professional.
Common Fibre Intake Mistakes to Avoid
Reaching your fibre target is not simply about adding as many grams as possible. How quickly you increase fibre, where it comes from and how your body responds can all matter.
Increasing Fibre Too Quickly
A large, sudden increase can cause bloating, gas or changes in bowel habits for some people. If your usual intake is low, increasing fibre gradually may be more comfortable.
Focusing Only on the Number
Hitting a particular gram target does not automatically make a diet balanced. The foods providing the fibre also contribute nutrients and affect the overall quality of your diet.
Relying on One Fibre Source
Different plant foods contain different types and combinations of fibre. Variety across whole grains, legumes, fruits, vegetables, nuts and seeds can provide a broader mix.
Forgetting About Fluids
Fluid intake remains important as dietary fibre increases. Individual fluid needs vary according to factors such as activity, environment, body size and overall diet.
Assuming Every Serving Is the Same
Fibre content changes with serving size, variety, preparation and product formulation. Nutrition labels can be useful when you need the fibre amount for a specific packaged food.
Assuming More Is Always Better
The calculator provides a reference target, not a challenge to consume as much fibre as possible. Very high intakes are not necessarily appropriate for every person.
A Better Approach to Your Fibre Target
Use your calculated result as a practical reference while paying attention to food variety, gradual changes and your individual tolerance.
If you currently eat little fibre, make manageable changes rather than trying to reach the full target immediately.
Include different plant foods rather than depending on one food or fibre source for most of your intake.
Day-to-day intake can vary. Your calculated result is a reference point rather than an exact number that must be reached every day.
Certain digestive or medical conditions can change the amount or type of fibre that is appropriate. Follow individual medical advice if you have been prescribed a low-fibre, modified-fibre or other therapeutic diet.
When Might Your Fibre Needs Be Different?
The calculator provides a general adult reference based on age and sex. Some life stages, health conditions and individual circumstances require different fibre guidance or a more personalised approach.
Children & Teenagers
Fibre reference values differ across childhood and adolescence. Because this calculator is designed for adults aged 19 and older, it should not be used to determine a child's or teenager's fibre target.
Pregnancy & Breastfeeding
Pregnancy and breastfeeding have separate nutrition reference values. The standard adult result from this calculator is therefore not intended to provide a pregnancy or breastfeeding fibre target.
Digestive Conditions
Some gastrointestinal conditions, symptoms, procedures or stages of treatment may require changes to the amount, type or texture of fibre consumed. General targets may not be appropriate in these situations.
Therapeutic or Restricted Diets
If a health professional has recommended a low-fibre, low-residue, modified-fibre or other therapeutic diet, that individual advice takes priority over the general result produced here.
What This Calculator Does — and Doesn't — Do
Understanding the limits of the result helps you use the calculator appropriately.
It matches adults aged 19 and older with the age- and sex-based fibre reference used by this calculator.
The result cannot determine the cause of constipation, diarrhoea, bloating, abdominal discomfort or other digestive symptoms.
It cannot account for your complete medical history, medications, digestive tolerance, therapeutic diet or other individual factors.
If you have a diagnosed digestive condition, significant or persistent gastrointestinal symptoms, have recently had gastrointestinal surgery, or have been given specific dietary instructions, speak with an appropriately qualified health professional before making substantial changes to your fibre intake.
Fibre Intake Calculator FAQs
Find answers to common questions about daily fibre targets, fibre-rich foods and how to use your calculator result.
The adult reference values used by this calculator are 38 g per day for men aged 19–50, 30 g for men aged 51 and older, 25 g for women aged 19–50, and 21 g for women aged 51 and older. Individual needs and appropriate intake can differ.
The calculator uses your age and the sex selected for estimation to match you with the corresponding adult fibre reference category. It is a reference-value lookup rather than a calculation based directly on body weight, height or activity level.
Fibre is naturally present in many plant foods. Useful sources include beans, lentils, chickpeas, whole grains, vegetables, fruits, nuts and seeds. Eating a variety of these foods can help contribute toward your daily fibre intake.
If your current fibre intake is relatively low, increasing it gradually may be more comfortable. A sudden large increase can cause gas, bloating or changes in bowel habits for some people.
Adequate fluid intake is important as dietary fibre intake increases. Fluid requirements vary between individuals depending on factors such as activity, environment, body size and overall diet.
Your calculator result is best treated as a general reference rather than an exact number that must be reached every day. Daily food intake naturally varies, so the overall pattern of your diet is also important.
Fibre supplements can provide particular types of fibre, but they do not provide the same overall nutritional profile as eating a variety of fibre-rich plant foods. If you are considering a supplement for a medical or digestive reason, discuss its suitability with an appropriately qualified health professional.
No. This calculator is designed to provide general reference values for adults aged 19 and older and does not provide separate targets for children, teenagers, pregnancy or breastfeeding. People following therapeutic diets or managing digestive or medical conditions may also require individual guidance.
This calculator and its supporting information are educational tools and are not a substitute for individual medical or dietetic advice.
Sources & References
The Fibre Intake Calculator uses established nutrition reference values and supporting guidance from authoritative health and nutrition organisations.
The calculator uses adult Adequate Intake reference values for total fibre: 38 g/day for men aged 19–50, 30 g/day for men aged 51 and older, 25 g/day for women aged 19–50, and 21 g/day for women aged 51 and older.
National Academies — Dietary Reference Intakes
Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. This publication establishes Adequate Intakes for total fibre and provides the primary reference framework used by this calculator.
View National Academies reference →National Academies — Recommended Intakes Table
The Dietary Reference Intake tables list total fibre values by life-stage group, including the adult male and female values used in the calculator.
View DRI reference table →NHS — How to Get More Fibre Into Your Diet
Practical guidance covering fibre-rich foods, dietary variety, food labels and ways to increase fibre intake as part of a balanced eating pattern.
View NHS fibre guidance →NHS — Constipation Guidance
NHS guidance recommends gradually increasing dietary fibre and maintaining adequate fluid intake, supporting the practical guidance presented on this page.
View NHS guidance →Nutrition recommendations can differ between countries and organisations. This calculator uses the age- and sex-specific adult Adequate Intake values described above as its consistent reference framework. The result is educational and does not replace personalised medical or dietetic advice.
Ready to Calculate Your Fibre Intake?
Use the free Fibre Intake Calculator to estimate your daily fibre reference based on your age and sex, then use the guidance above to put your result into context.