Water Intake Calculator — How Much Water Should YOU Drink?

Weight-based baseline, plus honest adjustments for workouts and hot weather — get a realistic daily target in liters, cups and bottles.

Quick answer: Free water intake calculator: your daily hydration target based on weight, activity and climate — in glasses, liters and cups. Instant, no sign-up.

Liters / day
Glasses (250 ml)
500 ml bottles

💡 Total fluids count — tea, coffee, soups and fruit all help. Spread through the day; thirst is a fine guide for most people.

How to use

  1. Enter weight — kg or lb, pick your unit.
  2. Add activity & climate — exercise minutes per day and whether you're in a hot climate.
  3. Get your target — liters per day plus glasses and bottles to actually hit it.

About this tool

The old “8 glasses” rule ignores body size and lifestyle. The evidence-based baseline is ~30–35 ml per kg of body weight, plus ~500–600 ml per hour of exercise and 10–20% more in hot climates. This calculator applies exactly that — including a gymnastic-free adjustment for AC life vs Gulf summers — and converts the target into glasses (250 ml), US cups and common bottle sizes so “drink more water” becomes a countable number.

FAQ

Is 8 glasses of water a day real?
It's a rough folk rule — a 50 kg office worker and 95 kg athlete shouldn't drink the same. Weight + activity based targets are the honest approach.
Does coffee/tea count?
Yes — moderate caffeine doesn't dehydrate; soups and fruit count too. The target is total fluid, not plain water only.
Can I drink too much?
Rarely, but yes (hyponatremia) — spread intake through the day and don't force liters beyond thirst during heavy drinking challenges.