Nishaana
Water intake calculator — your daily target.
This water intake calculator turns your body weight, training and climate into a daily water target. It starts from about 30 to 40 ml/kg, then adds roughly 500 to 700 ml per hour of exercise and a heat adjustment. Enter your details below; it updates instantly in litres and cups, no signup.
The hydration math, explained.
No black box. It is a practical heuristic, not a hard formula — built from weight, training and heat.
~30–40 ml per kg The everyday need before training. An 80 kg adult starts at about 2.4–3.2 L. This tool uses 35 ml/kg as the midpoint.
+500–700 ml per hour To replace sweat. A one-hour session adds roughly +0.6 L; longer or harder sessions add more. Check by weighing before and after.
hot → +10–15% Heat and humidity raise sweat loss, so a hot day nudges the total up; a cool day nudges it down. Thirst is still your best real-time signal.
This is a starting point, not a prescription — individual needs vary with sweat rate, diet and health. Food and other drinks count toward the total, so do not force water past comfortable. Endurance athletes should avoid over-drinking in long events. Pair it with your daily protein target.
Related nutrition calculators.
Build the rest of your daily plan around your hydration — protein, creatine, caffeine — and track it all.
Protein calculator
Your daily protein target in grams by weight and goal.
Open toolCreatine calculator
Your loading and daily maintenance creatine dose.
Open toolCaffeine calculator
Your pre-workout caffeine range and daily ceiling.
Open toolNutrition tracker
Log water, protein and macros every day in the browser.
Open toolDaily water questions.
How much water should I drink a day?
A practical baseline is about 30 to 40 millilitres of water per kilogram of body weight per day, before training. For an 80 kg adult that is roughly 2.4 to 3.2 litres. That total counts all fluids, and food provides another portion on top, so you rarely need to force water beyond thirst plus this target.
How much water should I drink based on my weight?
Use about 30 to 40 millilitres per kilogram of body weight. A 60 kg person lands near 1.8 to 2.4 litres, an 80 kg person near 2.4 to 3.2 litres, and a 100 kg person near 3 to 4 litres. Add roughly 500 to 700 millilitres for every hour of hard training or heavy sweating.
Should I drink more water when I work out?
Yes. Training raises your needs through sweat, so add roughly 500 to 700 millilitres of water per hour of exercise, more in heat. A simple check is body-weight change: if you lose weight during a session, you under-drank, so aim to replace about 1.5 litres per kilogram lost.
Can you drink too much water?
Yes, though it is uncommon. Drinking far more than you need over a short window can dilute blood sodium, a condition called hyponatraemia, which is a risk mainly for endurance athletes over-drinking during long events. For most people, spreading intake across the day and following thirst keeps you safe.
Does coffee and tea count toward water intake?
Yes. The mild diuretic effect of everyday coffee and tea is outweighed by their water content, so they count toward your daily total. Water is still the cleanest choice, and if you are chasing a caffeine target, size those drinks with the caffeine calculator so they do not push you past your ceiling.
Save your water goal. Hit it daily.
Free in your browser — Nishaana counts each glass toward your target and reminds you when you are behind, no app store needed.
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