Find your daily hydration target in seconds. Enter your weight and how much you exercise to see how much water you should drink per day, shown in litres, cups and ounces.
This is a general hydration estimate. Climate, exercise, diet, pregnancy, medicines and health conditions can change needs.
A visual summary that updates with your calculation.
Compare two scenarios and export the current calculation.
Save the current inputs and result as Scenario A or Scenario B.
Not saved yet.
Not saved yet.
Download the current inputs and result as a CSV file.
This calculator gives an instant estimate from the values entered above. Use the result as a planning starting point, then review the assumptions and limitations.
Enter the requested values using consistent units. Change one input at a time when comparing scenarios, and verify every value before using the result.
The estimate uses the values currently entered and the formula described on this page. Any fees, taxes, timing rules or personal circumstances not requested are excluded.
This calculator gives a general hydration estimate from body weight and activity inputs.
The tool applies its displayed weight-based baseline and adds the selected activity adjustment.
If the selected baseline is 35 mL/kg, a 70 kg adult starts at about 2.45 litres before activity adjustments.
The result is a planning estimate and includes no clinical assessment of fluid balance.
Needs vary with climate, diet, pregnancy, illness, medicines, kidney or heart conditions and exercise. Excess water can also be harmful. Follow professional advice when fluid intake is medically restricted.
Method reference: National Academies: Dietary Reference Intakes for Water. Fynzo explains and implements the calculation independently; the linked organization does not endorse this website.
Reviewed by: Yasser Chahir, Fynzo editor. Last reviewed: July 31, 2026.
More health calculators to help you plan.