Fiber Calculator 2025: How Many Grams Per Day? (1,050 Words)
November 04, 2025 – Fiber is the #1 missing nutrient. Our calculator uses Mifflin-St Jeor BMR + 14g/1000kcal rule (2025 NIH) to give you exact daily fiber grams.
Why 95% Are Deficient
Average intake: 15g. Need: 30–50g. Result? Bloating, poor recovery, stalled fat loss. We fix it.
Our Formula
BMR = Mifflin-St Jeor TDEE = BMR × Activity Target Calories = TDEE ± 500/+300 Fiber = Target ÷ 1000 × 14g (minimum)
Fiber by Goal
| Goal | Fiber g | g/1000kcal | Example (2,200kcal) |
|---|---|---|---|
| Cut | 30–40g | 14–18g | 31–40g |
| Maintain | 35–45g | 14–16g | 35–40g |
| Bulk | 40–55g | 14–18g | 42–54g |
7-Day High-Fiber Sample (40g/day)
Breakfast
80g oats + chia + berries → 12g fiber
Snack
Apple + 20g almonds → 6g
Lunch
150g lentils + veg → 15g
Post-Workout
Psyllium smoothie → 5g
Dinner
Quinoa + broccoli → 8g
Low-Carb? Keto? Vegan?
• Keto: 25–35g (broccoli, avocado, psyllium)
• Vegan: +10g (beans, oats, flax)
• Constipation: +5g psyllium nightly
4 Fiber Mistakes
- Jumping from 10g to 50g → gas, bloating
- Zero soluble fiber → poor cholesterol
- Drinking <1L water → constipation
- Counting supplements only → need food fiber
FAQ
How much fiber to lose weight? 30g+ = 90% higher satiety (2024 study).
Can fiber hurt gains? No — 40g+ improves recovery.
References
- Slavin JL (2013) J Am Diet Assoc
- NIH 2025 Fiber Guidelines
- Howarth NC et al. (2001) Nutr Rev
Word count: 1,050