Water Intake Calculator
Rough fluid target from body weight with simple adjustment thinking.
Use the calculator below, then review the formula, a numeric example, and the reference table to understand how the daily water intake result is produced.
Educational tool only. It does not replace advice from a licensed clinician, dietitian, or exercise physiologist.
Calculator inputs
Result
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What is this calculator?
Rough fluid target from body weight with simple adjustment thinking. The formula, a worked example, and a reference table are below. Results are for education only, not medical advice.
How it works
Illustrative baseline: ml/day ≈ body weight (kg) × 35 (heuristic; not a medical fluid prescription).
Example
70 kg ~2450 ml/day baseline illustration before exercise/heat adjustments.
Reference Table
| Value | Meaning |
|---|---|
| Exercise | Add fluid for sweat loss |
| Heat | Increase on hot days |
| Illness | Fever/vomiting may raise needs |
FAQ
Coffee dehydrate?
Moderate caffeine usually counts toward fluids for healthy adults.
Kidney disease?
Fluid limits may apply—follow nephrology advice.
Thirst reliable?
Often yes, but athletes and older adults may need schedules.
Electrolytes?
Long sweat sessions may need sodium—not just water.