How Much Water Should You Drink Today?
Daily water needs vary from person to person, driven mainly by body weight, activity level, and weather. This calculator starts with a baseline amount based on your weight, then adds extra for activity and heat, so you get a realistic target for today.
The baseline is roughly 30 ml of water per kilogram of body weight. On top of that, light activity adds 350 ml and sweaty exercise or physical labor adds 700 ml, while a temperature of 82°F or higher adds 500 ml and a hot day of 90°F or above adds a full 1,000 ml — accounting for the extra fluid lost through sweat and temperature regulation.
The result is your total target for the day, so it's better to spread it across morning, afternoon, and evening rather than drinking it all at once. Caffeinated drinks like coffee and tea have a mild diuretic effect and hydrate less effectively than plain water, so try to meet most of your target with water or caffeine-free beverages. A pale yellow urine color is generally a good sign you're well hydrated, while dark yellow suggests you should drink more.
Frequently Asked Questions
Caffeinated drinks have a mild diuretic effect, so they hydrate somewhat less effectively than plain water. Try to meet the recommended amount mostly with water or caffeine-free drinks.
Spreading intake in smaller amounts throughout the day is more effective for absorption than drinking a lot at once. Drinking excessive amounts in a short time can even risk hyponatremia, so pace yourself.