How much water should I drink per day?

The WHO recommends 2.5L per day for men and 2.0L for women from all sources. However, optimal intake is individual — active people, those in hot climates, breastfeeding women, and larger-bodied people need significantly more. Our calculator personalises your target based on these factors.

Does coffee count as water intake?

Yes. Despite its mild diuretic properties, the fluid in coffee more than compensates. The British Dietetic Association confirms that coffee and tea count toward daily fluid intake. However, water and electrolyte-containing drinks are preferable for hydration during exercise.

Water Intake Calculator — Free Daily Hydration Calculator (2026)

💧 Daily Water Intake Calculator

Personalised for weight, activity, climate & age · Results in litres, ml, and glasses

Weight (kg)

Age

Sex

Pregnancy/Breastfeeding

Exercise per day

Climate

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Daily Target

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Millilitres

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Glasses (250ml)

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Per Waking Hour

💧 Hydration Tips

Drink a large glass of water first thing in the morning — you wake up mildly dehydrated after 7–8 hours without fluids.
Monitor urine colour: pale yellow = well hydrated. Dark yellow = drink more. Clear = you may be overhydrating.
Eat water-rich foods: cucumbers (96% water), watermelon (92%), leafy greens (85–95%) count toward daily intake.
Set hourly phone reminders to sip water — most people underestimate how little they drink without prompting.

⚠️ Individual hydration needs vary. Drink to thirst and monitor urine colour as primary guides. Consult a doctor if you have kidney conditions or are on diuretics.

How Much Water Should You Drink Per Day?

The commonly cited "8 glasses a day" (about 2 litres) is a useful starting point, but optimal hydration is individual. The European Food Safety Authority (EFSA) recommends 2.5L per day for men and 2.0L for women — including water from food. The US National Academies recommend 3.7L total daily fluid for men and 2.7L for women from all sources.

These are population averages. Your actual needs are higher if you exercise, live in a hot climate, are breastfeeding, or are physically large. Our calculator accounts for all these factors.

The Consequences of Dehydration

Dehydration Level	Body Weight Lost	Effects
Mild	1%	Thirst, slightly reduced focus, reduced exercise tolerance
Moderate	2%	Up to 10% reduction in aerobic performance, headache, dry mouth
Significant	3–4%	Impaired cognitive function, fatigue, muscle cramping
Severe	5%+	Heat exhaustion, rapid heart rate, medical emergency

Does Coffee Count Toward Daily Water Intake?

Yes — despite its reputation, moderate coffee consumption (2–4 cups/day) does contribute to daily fluid intake. While caffeine has mild diuretic properties, the fluid in coffee more than compensates. The British Dietetic Association confirms that coffee and tea can count toward daily fluid intake.

Frequently Asked Questions

For many sedentary adults in temperate climates, 8 glasses (2 litres) is a reasonable baseline. However, active individuals, those in hot climates, pregnant/breastfeeding women, and larger-bodied people need considerably more. Use our calculator for a personalised target based on your specific situation.

Yes — overhydration (hyponatremia) is a real but rare risk, usually only in endurance athletes who drink excessive water during long events without replacing electrolytes. For most people, thirst and urine colour are reliable guides. Aim for pale yellow urine, not clear.

Exercise significantly increases fluid requirements. A typical 60-minute workout causes 0.5–2 litres of fluid loss through sweat, depending on intensity and climate. The American College of Sports Medicine recommends drinking 400–600ml of water 2 hours before exercise, and 150–250ml every 15–20 minutes during exercise.