Daily Hydration Calculator – How Much Water Should You Drink Per Day?

Why calculate daily water intake?
Proper hydration is crucial for health – it affects your energy level, brain function, digestion, and even weight management. Everyone’s water needs are different. Factors like body size, activity, and climate change how much water you should drink. This Hydration Calculator gives you a personalized estimate of how much water in liters per day you need to stay well-hydrated.

How the calculator works:
A common guideline for daily water intake is about 30–35 ml of water per kilogram of body weight​

. This roughly translates to 0.03 liters per kg. Our calculator uses this baseline formula and then adjusts for activity level:

• Sedentary or Light Activity: (~30 ml/kg) – if you have a desk job and minimal exercise.
• Moderate Activity: (~35 ml/kg) – for those who exercise a few times a week or have an active job.
• High Activity or Athlete: (~40+ ml/kg) – if you do intense exercise daily or work in very hot conditions.

You will input your weight and select your typical activity level. The calculator will output your recommended daily water intake. For convenience, results are given in liters and (approximate) cups.

Example: A moderately active person weighing 70 kg (~154 lbs) would need around 70 × 0.035 = 2.45 liters per day, which is about 10 US cups of water. If that person were highly active, the recommendation might increase to ~2.8–3 liters (about 12 cups).

Tips for staying hydrated:

• Carry a water bottle: Having water on hand makes it easier to sip throughout the day.
• Watch for thirst: Thirst is a late sign of dehydration. Try to drink before you feel very thirsty.
• Check urine color: Light yellow or clear urine usually means you’re well hydrated; dark yellow suggests you need more water.
• Include hydrating foods: Fruits and veggies (like watermelon, cucumber, oranges) have high water content and count toward your fluid intake.
• Adjust for conditions: On hot days or when sweating a lot, increase your water intake. Likewise, at high altitudes or during illness (fever, diarrhea), you may need more fluids.

Important: This calculator provides a general recommendation. Individual needs can vary. Pregnant or breastfeeding women often need extra fluids. Certain health conditions (like kidney problems) might require fluid restrictions – follow your doctor’s advice in such cases. For most healthy individuals, the provided amount is a good target. Remember that other beverages (tea, etc.) and watery foods contribute to hydration, but water is usually the best and simplest choice.

Staying adequately hydrated helps you feel and perform your best. Use this tool to set a daily water goal and try to meet it consistently. Your body will thank you!