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Water Intake Calculator Tool

Enter your body weight, age, and exercise time to estimate your daily water intake in ml, liters, and cups. Supports age-based coefficients and an exercise add-on for hydration and health management.

Last updated: 2026/10/16 Calculator Feedback & bug reports
Input
Please enter a value between 1 and 300 kg
Results
Daily Water Intake
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--
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* Calculated as 1 cup = 200 ml
Breakdown
Base (by body weight) --
Exercise add-on --
Total --
Target from Drinks
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* About 20-30% of daily water comes from food, so the drink target is roughly 80% of the total.
These results are general estimates only and are not medical advice or a diagnosis. Actual water needs vary widely with body type, temperature, humidity, activity, medical conditions, and medications. If you have fluid restrictions due to heart or kidney conditions, or any concerns about your health or hydration, please consult a doctor or specialist.

How to Use

1

Enter your weight

Enter your body weight (kg). Your daily water intake is calculated in real time as you type.

2

Adjust age and exercise (optional)

Enter your age to apply an age-based coefficient. If you exercise, enter your daily exercise time (minutes) to add water lost through sweat.

3

Check the results

Your estimated water intake is shown in ml, liters, and cups. You can also see the target amount to drink.

4

Copy the results

Use the "Copy Results" button to copy the calculation as text for your notes or records.

About Water Intake Calculation

Daily water needs are commonly estimated at around 30-40 ml per kg of body weight. This tool applies an age-based coefficient to your weight and adds water lost through exercise. Results are shown in ml, liters, and cups, along with a target amount to drink. All processing happens in your browser, and no data is sent to servers.

Features

  • Instant CalculationJust enter your weight to instantly estimate your daily water intake in ml and liters.
  • Age-Based CoefficientsAutomatically applies a coefficient (30-40 ml/kg) based on your age for a more realistic estimate.
  • Exercise Add-OnEnter exercise time to add water lost through sweat, and see how many cups it equals.
  • Privacy ProtectedAll calculations happen in your browser. Your data is never sent to servers.

Use Cases

  • Setting a daily hydration goal
  • Heatstroke and dehydration prevention
  • Diet and health self-checks
  • Planning hydration for sports and exercise
  • Checking water intake for elderly family members

FAQ

What is the formula for daily water intake?
A common estimate is "body weight (kg) x 30-40 ml". This tool uses 40 ml for under 30, 35 ml for ages 30-54, and 30 ml for 55+ (per kg of body weight). For example, 60 kg at 35 ml/kg gives 60 x 35 = 2,100 ml.
Do I need to drink all of this water?
No. About 20-30% of your daily water comes from food (rice, soup, vegetables, fruit, etc.), so the target from drinks is roughly 80% of the total. This tool also shows the "Target from Drinks" amount.
How much more should I drink when exercising?
Sweat loss varies by person, but this tool adds about 500 ml per 30 minutes of exercise. Higher temperature, humidity, and intensity increase sweat loss, so drink to thirst and replenish frequently as needed.
Should I drink a large amount at once?
It is generally better to sip about one cup at a time, several to a dozen-plus times throughout the day, rather than drinking a lot at once. Timing around waking up, bathing, before bed, and around exercise helps build the habit.
Are these results medically accurate and safe?
These results are general estimates only, not medical advice or a diagnosis. Water needs vary widely with body type, temperature, activity, medical conditions, and medications. If you have fluid restrictions due to heart or kidney conditions, or any health concerns, consult a doctor instead of self-judging. All calculations run in your browser and no data is sent externally.

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Related Guides

How Much Water Do You Need a Day? Weight-Based Targets and Tips Learn how to estimate your daily water needs from body weight. Covers the weight x 30-35 ml guideline, water from food, how exercise and heat change the amount, the risks of overdrinking, and tips for steady hydration. General health information.