Health & Fitness
Water Intake Calculator
Water Intake — water Intake Calculator estimates daily water need from body weight (roughly 30–35 ml per kg). This page runs that same calculation on your numbers, in your browser: no signup, no uploads, nothing stored.
Use Water Intake Calculator to estimate your daily water intake: give it your weight and activity level, press Calculate, and read off a daily target in litres and glasses — all worked out on your device.
About this calculator
Get water intake right and the rest of the task gets easier. Water Intake Calculator estimates daily water need from body weight (roughly 30–35 ml per kg). It matters when you want a quick screening number before deciding whether a habit, plan or measurement deserves a closer look. A common rule of ~35 mL per kg gives a 70 kg adult 70 × 35 = 2,450 mL (~2.5 L)/day ; needs rise with heat and activity. The tool above does the same computation in your browser — free, private, nothing stored.
How to use
- Enter your body weight in kilograms for the water target.
- Choose your typical activity level.
- Press Calculate to see a daily water target.
- Drink more in heat or during intense exercise.
Why use Water Intake Calculator
Fast
Calculations run in your browser. No round trip to a server.
Private
Your inputs never leave your device. Nothing is uploaded.
Free
No signup, no paywall, no ads-in-results, no watermarks.
Educational
Uses common estimation formulas for educational purposes. Results are not medical advice and should not replace professional guidance.
Mobile-ready
Optimised for phones, tablets, and desktops alike.
Transparent
Clear about formulas used and their limits, with disclaimers where they matter.
Common uses
Use it when tracking progress over time
Water Intake alongside a workout plan
Use it for everyday fitness check-ins
Use it for comparing before-and-after
Use it when logging weekly numbers
Use it when learning what a metric means
Technical notes
Water Intake Calculator estimates daily water need from body weight (roughly 30–35 ml per kg).
These are general-population estimates and not a substitute for advice from a qualified clinician.
Because it runs locally, results appear instantly with no server round-trip.
FAQ
How much water should I drink daily?
A common baseline is about 35 ml per kg of body weight, so 70 kg is roughly 2.4–2.5 litres, with more added for activity, heat, or illness.
Does activity change my water needs?
Yes — sweating during exercise raises fluid loss, so active and very active days need extra water beyond the resting baseline.
Does food count toward hydration?
Yes. Many foods, especially fruit and vegetables, contain water and contribute to your total daily intake along with all beverages.
Does the Water Intake Calculator send my data to a server?
No. The Water Intake Calculator runs entirely in your browser — your inputs never leave your device, and nothing is uploaded or stored.
Worked example
A common rule of ~35 mL per kg gives a 70 kg adult 70 × 35 = 2,450 mL (~2.5 L)/day; needs rise with heat and activity.