Fiber Intake Calculator
Most people don't eat enough fiber. This calculator shows your daily fiber target based on your age and sex or your calorie intake, plus simple ways to reach it.
The Dietary Guidelines for Americans recommend 14 grams of fiber per 1,000 kcal consumed. The Institute of Medicine advises 38 grams daily for men and 25 grams for women aged 19 to 50.
Recommended Daily Fiber
Evidence-Based StandardCalorie Target: 31g · IOM Age Standard: 38g. Increase daily fiber gradually by 3 to 5 grams per week while increasing fluid intake to prevent gastrointestinal discomfort or bloating.
High-Fiber Whole Food Sources
| Food Item | Fiber per Serving |
|---|---|
| Lentils & Beans (1 cup cooked) | 15–16 g |
| Chia Seeds (2 tbsp) | 10 g |
| Raspberries / Blackberries (1 cup) | 8 g |
| Oats / Porridge (1 cup cooked) | 4–5 g |
| Avocado (medium) | 9 g |
| Apple with skin | 4.4 g |
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Clinical Equations
WHO, CDC, ACSM & Mifflin-St Jeor
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How to use Fiber Intake Calculator
- 1Enter your age and biological sex.
- 2Enter your daily calorie intake.
- 3View your recommended fiber target and whole food dietary sources.
Health benefits of dietary fiber
Fiber regulates gut microbiome diversity, improves insulin sensitivity, lowers LDL cholesterol, and prolongs gastric emptying to support fullness on fewer calories.
Frequently Asked Questions
How much fiber do I need a day?
About 25 g for women and 38 g for men aged 19 to 50, or 14 g per 1,000 kcal.
Can I eat too much fiber?
Very high amounts, or increasing too fast, can cause bloating. Add 3 to 5 g per week and drink more water.
Does fiber help with weight loss?
It helps you feel full on fewer calories, which can make a deficit easier.
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Scientific Sources & Evidence
- World Health Organization (WHO) — Body Mass Index Classification
- CDC Growth Charts — BMI-for-age LMS Percentiles
- Mifflin et al. (1990) — Basal Metabolic Rate Predictive Equations
- NICE Guideline NG246 — Identification and Management of Overweight and Obesity
- American College of Sports Medicine (ACSM) — Exercise Testing & Prescription
- European Food Safety Authority (EFSA) — Dietary Reference Values for Water