Hydration Reminder Calculator

Hydration reminder calculator

This tool turns your body weight and activity into a daily fluid target, then spreads it across your waking hours so you know roughly how often to take a drink. It helps you build a steady drinking habit instead of gulping a lot at once or forgetting entirely.

How it works

The estimate uses two common general guidelines:

• Base = body weight (kg) × 35 ml
• Exercise add-on = exercise hours × 500 ml
• Daily target = (base + add-on), shown in litres

It then converts the target into the number of glasses of your chosen size (target ÷ glass size) and spreads them evenly across your waking hours to suggest a reminder interval: interval = (waking hours × 60) ÷ glasses. Smaller glasses or more fluid mean more frequent sips; more waking hours stretch them out.

Example

For a 70 kg person, 1 hour of exercise, 16 waking hours, 250 ml glass:

• Base = 70 × 35 = 2,450 ml; exercise = 500 ml → target = 2,950 ml ≈ 2.95 L
• Glasses = 2,950 ÷ 250 = 11.8 glasses
• Interval = (16 × 60) ÷ 11.8 ≈ a drink every 81 minutes

This is a general guideline, not medical advice. Calculated entirely in your browser; nothing is uploaded.