Rex says
Same equations the textbooks use — just way less awkward. Pop in your stats and I'll tell you what the number actually means for you.
Try a scenario
Click to load — tweak from there.Inputs
Result
Liters / day
2.70
Fluid ounces / day
91.3
8-oz cups / day
11.2
Psst — share this and help Rex grow
One click, a permanent link with your numbers baked in.
How to use this
- 1Enter units.
- 2Enter weight.
- 3Enter activity.
- 4Read your liters / day on the right — it updates as you type.
- 5Hit Share to keep the scenario or send it to someone.
About this calculator
Estimates daily water need at ~35 ml per kg, with a bump for active days.