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Water Intake Calculator

Estimate how much water to drink each day from your body weight, daily exercise, and climate, with the total in liters, US ounces, and 8-oz cups.

Weight units

Calculated in your browser. Nothing is uploaded.

Optional. Leave blank for a resting-day baseline.

Climate

Enter your body weight to see your daily water target.

How to calculate your daily water intake

  1. Enter your body weight

    Choose kilograms or pounds, then type your body weight. The estimate appears at once; there is no button to press.

  2. Add exercise and climate

    Enter your typical daily exercise in minutes and pick a temperate or hot climate to adjust the target.

  3. Read your daily target

    Your recommended water shows in liters, US ounces, and 8-oz cups, with a breakdown, and Copy water target saves it to your clipboard.

Why use this tool

Weight, exercise, and climate

The estimate starts from your body weight, adds an allowance for how long you exercise, and raises the target in hot conditions.

Three units at once

Every result is shown in liters, US fluid ounces, and 8-oz cups, so you can read it in whichever unit you already think in.

See where the number comes from

A breakdown separates the water from your body weight, your exercise, and a hot climate, so the total is never a black box.

Realistic, capped estimates

Extreme weights and exercise times are capped and the total is limited to a sensible ceiling, so the figure stays useful rather than alarming.

Your numbers stay on your device

Weight and exercise are processed by the page alone. Nothing is uploaded, stored, or logged.

About this tool

This water intake calculator estimates how much water to drink in a day from three things that move the number most: your body weight, how long you exercise, and whether your climate is temperate or hot. It starts from roughly 33 ml of water per kilogram of body weight (about 0.5 US ounces per pound), adds around 350 ml for every 30 minutes of exercise, and adds a further bump in hot conditions. The total is shown three ways at once, in liters, in US fluid ounces, and in 8-ounce cups, so you can pick whichever unit you actually think in.

Use it as a sensible starting point rather than a strict rule. Real fluid needs vary with age, pregnancy, altitude, illness, medication, and how much water you already get from food, none of which a short form can capture. Food typically supplies a fair share of daily fluid, and drinks like tea and juice count too, so you rarely need to hit the full figure from plain water alone. Extreme inputs are capped so the estimate stays realistic, and very high needs are best guided by a health professional.

Everything is worked out on the page as you type, and the weight and exercise figures you enter are never uploaded, stored, or logged. For related numbers, the TDEE calculator estimates the calories you burn in a day, the BMI calculator relates weight to height, and the unit converter handles standalone conversions such as pounds to kilograms or liters to ounces.

Frequently asked questions

How much water should I drink a day?
A common starting point is about 33 ml of water per kilogram of body weight, or roughly 0.5 US ounces per pound. This tool applies that, then adds around 350 ml for every 30 minutes of exercise and a further allowance for hot climates, and shows the total in liters, ounces, and cups.
How do exercise and climate change the number?
Exercise raises fluid loss through sweat, so the estimate adds about 350 ml for each 30 minutes you spend exercising. Choosing a hot climate adds a further percentage on top, since heat increases how much you sweat even at rest. Leave exercise at zero and pick temperate for a baseline figure.
Do other drinks and food count toward the total?
Yes. The figure is your total daily fluid, not water you must drink from a glass. Food often supplies a fair share of it, and tea, coffee, milk, and juice all count, so you rarely need to reach the full number from plain water alone.
Can I see the amount in ounces and cups?
Every result appears in three units side by side: liters, US fluid ounces, and 8-ounce cups. The weight input can be entered in kilograms or pounds, but the output always shows all three units so you can use whichever you prefer.
Is this suitable for everyone?
It is a general estimate for healthy adults and not medical advice. Children, pregnant or breastfeeding people, and anyone with a heart, kidney, or fluid-restriction condition can have very different needs, so treat the number as a rough guide and follow a health professional for anything specific.
Is my data uploaded anywhere?
No. Everything runs in your browser; nothing is sent to a server. The weight and exercise figures you enter are never uploaded, stored, or logged.

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