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💧 Water Intake Calculator

Hydration target as a function of body weight, exercise minutes per day, and climate (hot vs temperate). Standard recommendation is ~33ml per kg of body weight, plus 500ml per hour of moderate exercise, plus 10-20% more in hot climates.

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Examples

Sedentary 70kg adult

Input70 kg, 0 exercise, temperate

Output~2.3 L (78 oz) per day

Athlete training 90 min

Input75 kg, 90 min exercise, hot climate

Output~3.7 L (125 oz) per day

Frequently asked questions

Does coffee count?

Yes — despite the myth, the diuretic effect of caffeine is mild and your net water gain from coffee is positive. Same for tea.

Can I drink too much water?

Yes — overhydration causes hyponatremia (low sodium). Stick to roughly 0.5-1 L per hour max in extreme heat.

About this tool

Water Intake Calculator runs entirely in your browser using standard Web APIs. No data is sent to any server. The source for this tool is in our public GitHub repository.

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Why this tool

vs typical free web-tool sites

	1vw	Typical free site
Price	Free	Free
Signup required	No	Often (for premium features)
Ads inside the tool	No	Yes (banner + video)
Data sent to server	No (browser-only)	Yes (inputs analyzed for ads)
Total tools	96	Often <20 or scattered across sites
Bookmarkable URL per tool	Yes	Mixed
Loads in under 1s	Yes (static)	Often slow (ad tracking)
Multilingual	EN / ES / PT / FR / DE	Usually EN only
Open source	Yes	No