Daily Water and Fiber Intake Calculator
This fiber calculator and daily water intake calculator estimates your daily fiber target and how much water to drink, from your weight, age and activity level. Every value shows its reference and its limits — general benchmarks, not medical advice.
Between 1 and 120 years
10–300 kg (22–660 lb)
0–300 min (optional)
Triggers a warning: needs can vary.
Calculated results
If you have heart or kidney disease, a fluid restriction, or any particular medical condition, this general estimate may not be suitable: seek professional advice.
Your indicative fiber reference is 28 g per day. The beverage estimate is 2.45 L (82.8 fl oz) per day. These values are general benchmarks, not a medical prescription.
Method and limits
How to use this calculator
Enter your age and weight, then pick your activity level and the nutritional reference sex. Select pregnancy or breastfeeding if it applies: the fiber table adjusts automatically. Optionally enter your daily minutes of intense activity to see a fluid supplement scenario, and flag a hot climate to get the matching warnings. Results update instantly and never leave your browser.
The fiber target is selected from a documented table of recommendations. The hydration estimate follows E_water = 35 × P (milliliters per day for a body weight P in kilograms), plus the scenario supplement E_activity = 500 × T/60, where T counts minutes of intense activity. These calculations do not determine anyone's exact individual needs.
Fiber: a reference table, not a universal constant
The daily fiber value is not computed by formula: it is read from a parameter table. The US DRI (Dietary Reference Intakes from the National Academies) sets 25 g/day for adult women and 38 g/day for adult men, adjusted to 28 g for pregnancy and 29 g for breastfeeding. Europe's EFSA recommends 25 g/day for all adults. The result always shows the selected reference, because these benchmarks differ by country and authority.
Water: the 35 ml/kg convention and an activity scenario
The base estimate follows E_water = 35 × P, rounded to 50 ml for readability. The activity supplement follows E_activity = 500 × T/60, with T the minutes of intense activity — a scenario hypothesis shown as such, never a prescription. The indicative total appears in milliliters and liters. A hot climate triggers a warning — needs can rise significantly — without automatically applying any supplement presented as universal.
Worked example
For a 30-year-old, 70 kg (154 lb) woman, not pregnant or breastfeeding, with 60 minutes of intense activity per day: fiber reference 25 g per day; base water 35 × 70 = 2,450 ml; activity supplement 500 ml; indicative total 2,950 ml — 2.95 L, about 99.8 fl oz or 12.5 US cups per day. Reproduce these values in the tool: you must get exactly the same results, the total being rounded to 50 ml for readability.
Assumptions and limits
If you have heart or kidney disease, a fluid restriction, or diuretic treatment, this general estimate may not be suitable: seek medical advice. Hydration needs are never presented as a diagnosis. This calculator is not designed for individualized pediatric needs, and pregnancy or breastfeeding call for adapted recommendations that the tool flags without replacing them. Heat, diet, medications and certain illnesses can all shift your actual needs.
| Constant | Value | Source |
|---|---|---|
| Fiber, adult woman (19–50 years), DRI reference | 25 g/jour | National Academies — Dietary Reference Intakes (DRI)Uncertainty : References vary by country and physiological state. |
| Fiber, adult man (19–50 years), DRI reference | 38 g/jour | National Academies — Dietary Reference Intakes (DRI)Uncertainty : References vary by country. |
| Starting hydration estimate (explicit convention) | 35 ml/kg/jour | Conventional estimation, à valider par un professionnelUncertainty : Planning assumption, not a medical prescription. |
Frequently asked questions
Limits of use