Nutrition
Fiber Intake Calculator
Fiber feeds your gut microbiome, steadies blood sugar, and lowers cholesterol, yet 95% of adults fall short. Fix your number.
Fiber recommendations are 38 grams per day for adult men and 25 grams for women, or about 14 grams per 1,000 calories eaten. Most adults consume only half of this. Pair the target with whole foods and adjust based on your own progress and energy levels.
Men: 38 g · Women: 25 g.
Or 14 g per 1,000 kcal.
Most adults eat only ~15 g.
Calculate Your Fiber Intake
Your Fiber Target
What Is Fiber Intake?
Dietary fiber is the indigestible part of plants. Soluble fiber (oats, beans, apples) lowers cholesterol and steadies blood sugar; insoluble fiber (whole grains, vegetables) keeps digestion moving.
Recommendations: 38 g/day for men and 25 g/day for women, or 14 g per 1,000 kcal. Most adults eat only about 15 g.
How It Is Calculated
Base: 38 g (men) · 25 g (women), or 14 g per 1,000 kcal
Example: Example: man eating 2,500 kcal → 35 g by calories; guideline 38 g → target 38 g
Fiber-rich foods
| Food | Fiber |
|---|---|
| Lentils, cooked (1 cup) | 15.6 g |
| Black beans, cooked (1 cup) | 15 g |
| Oats (1 cup cooked) | 4 g |
| Apple with skin | 4.4 g |
| Broccoli (1 cup) | 5 g |
| Whole-wheat bread (1 slice) | 2 g |
Limitations
- Increase fiber gradually with extra fluids.
- Some digestive conditions (IBS, diverticulitis flares) need modified fiber plans.
- Supplemental fiber doesn't replace whole-food variety.
Sources & Review
References used for this calculator’s formulas and thresholds:
Fiber Intake FAQ
How much fiber do I need daily?
Men 38 g, women 25 g, or 14 g per 1,000 kcal. Children need roughly age + 5–10 g.
What happens if I eat too little fiber?
Constipation, blood-sugar swings, higher LDL cholesterol, and a less diverse gut microbiome, all linked to low fiber.
How do I hit 38 g in a day?
1 cup lentils (15 g) + 1 cup oats (4 g) + an apple (4 g) + vegetables (10 g) + whole grains (5 g) gets you there.
Is too much fiber possible?
Rare from food, but jumping from 15 g to 40 g overnight causes bloating and gas — increase slowly.
A note before you begin: this tool offers educational estimates only. It cannot replace advice from your doctor or another qualified professional.