Water Intake Calculator
Enter your weight and activity level to get a daily hydration target.
Fill in the form and hit calculate to see your results here.
Your daily water target
This includes water from drinks generally — food and other fluids also contribute to your total daily intake.
Why bodyweight matters
Larger bodies have more tissue to hydrate and typically a higher metabolic rate, so total water needs scale with weight rather than being a single fixed number for everyone.
Exercise and sweat losses
Every 30 minutes of exercise adds meaningfully to fluid needs through sweat, so this calculator scales your target up with the amount of exercise you do.
Signs you need more
Dark urine, persistent thirst and headaches can all signal under-hydration — if you notice these regularly, it's worth increasing your intake beyond this estimate.
The formula
# Base need Base (ml) = weight(kg) × 33 # Exercise addition Exercise bonus (ml) = exercise minutes × 12 # Climate addition Hot / humid climate = + 500ml Total = base + exercise bonus + climate bonus
33ml per kg of bodyweight is a commonly cited general baseline for adults; individual sweat rates vary.
Common questions
Yes, in moderation — caffeinated drinks still contribute fluid overall, though it's still worth keeping plain water as your main source.
Often yes — many people find they need to consciously drink more water during a diet, partly because high-water foods like fruit are sometimes reduced.
Yes, in rare cases drinking extremely large amounts in a short period can be harmful. This calculator gives a sensible daily total, not a rate to drink it at.
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