Daily Fiber Intake Calculator
Calculate daily fiber intake from age, sex, and calorie needs per USDA guidelines.
Returns target, current deficit, and top food sources to close the gap.
Dietary fiber intake recommendations are based on age, sex, and caloric intake. Fiber is the indigestible portion of plant foods — it feeds gut bacteria, regulates blood sugar, lowers LDL cholesterol, and promotes satiety.
Daily fiber recommendation formulas:
Academy of Nutrition and Dietetics: Recommended Fiber = 14 grams per 1,000 calories consumed
So at 2,000 calories/day: 14 × 2 = 28 grams/day
Age and sex-based targets (US Dietary Guidelines):
- Men 19–50: 38 grams/day
- Men 51+: 30 grams/day
- Women 19–50: 25 grams/day
- Women 51+: 21 grams/day
- Children 1–3: 14 g/day | 4–8: 17–20 g/day | 9–13: 22–25 g/day
- Adolescents 14–18: 25–31 g/day
Soluble vs. insoluble fiber:
- Soluble fiber (dissolves in water → forms gel): lowers LDL cholesterol, slows glucose absorption, feeds beneficial gut bacteria. Found in oats, legumes, apples, psyllium husk.
- Insoluble fiber (does not dissolve): adds bulk, speeds gut transit, prevents constipation. Found in wheat bran, vegetables, whole grains.
Target ratio: roughly 75% insoluble : 25% soluble in a balanced diet.
Fiber content of common foods (per 100g):
- Psyllium husk: 71g fiber
- Chia seeds: 34g
- Lentils (cooked): 8g
- Black beans (cooked): 9g
- Avocado: 7g
- Broccoli (cooked): 3g
- Apple (with skin): 2.4g
- Brown rice (cooked): 1.8g
- White rice (cooked): 0.4g
Increasing fiber safely — gradual ramp: Adding too much fiber too quickly causes bloating, gas, and cramping. Increase by 5 grams per week until reaching target. Drink at least 8 cups (2L) of water/day — fiber absorbs water; without it, it can cause constipation instead of relieving it.
Worked example: 35-year-old woman, consuming 1,800 calories/day.
- Calorie-based target: (1,800 ÷ 1,000) × 14 = 25.2 grams/day
- Age/sex guideline: 25 grams/day — these align closely
- Current intake (estimated): 1 apple (2.4g) + salad greens (1g) + one serving whole-wheat bread (2g) + rice (1.8g) = ~7g/day
- Fiber gap: 25 − 7 = 18 grams short
- Easy fix: add ½ cup cooked lentils (4g) + 2 tbsp chia seeds (7g) + swap white rice for brown rice (+1.4g) → closes 12.4g of the gap with three simple swaps.