Is this a medical recommendation?

No. The number is a rough baseline from a simple weight-times-multiplier heuristic. It is not a diagnostic target and should not replace advice from a doctor or dietitian — especially if you are pregnant, nursing, taking medication, or living with a kidney, heart, or metabolic condition.

How much water should I drink per day?

A common rule of thumb is about 33 mL per kg of body weight. That puts a 70 kg person near 2.3 liters per day. Activity level and climate shift the number up or down. Treat it as a starting point, not a strict quota.

Does coffee count toward water intake?

Coffee and tea do contribute to your daily fluid intake. Caffeine has a mild diuretic effect, so water remains the best choice for hydration. Sugary or alcoholic drinks are poor substitutes.

What are signs of dehydration?

Common signs include dark urine, dry mouth, fatigue, dizziness, and headaches. Severe dehydration can cause rapid heartbeat, confusion, and fainting. Urine color is one of the simplest day-to-day checks.

Should I drink more water when exercising?

Yes. The American College of Sports Medicine suggests about 400-600 mL of water in the 2 hours before exercise, and 150-350 mL every 15-20 minutes during exercise, depending on sweat rate.

Can you drink too much water?

Yes. Overhydration (hyponatremia) can be dangerous — it happens when blood sodium drops too low from excessive plain water. It is rare in daily life but can occur during extreme endurance events.

HEAHealth & Fitness

Water Intake

Estimate a daily plain-water baseline from your weight, activity level, and climate. Rough heuristic, not medical advice. Results in liters, cups, and ounces.

Units

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Weight

Activity Level

Climate

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How It Works

Formula

V = m \times 0.033 \times A \times C

V_{\text{cups}} = \frac{V}{0.237}

V_{\text{oz}} = V \times 33.814

Where

$V$: Daily water intake(L)
$m$: Body weight(kg)
$A$: Activity multiplier (1.0 sedentary, 1.1 light, 1.2 moderate, 1.4 active, 1.5 very active)
$C$: Climate multiplier (0.85 cool, 1.00 mild, 1.10 warm, 1.20 hot & dry, 1.30 hot & humid)
$V_{\text{cups}}$: Daily water in 8 fl oz cups(cups)
$V_{\text{oz}}$: Daily water in fluid ounces(fl oz)

This is a rough heuristic for plain drinking water only — food and other beverages also contribute to hydration. "Climate" here is shorthand for the ambient temperature and humidity you spend most of your day in: cool (< 15 °C), mild (15–25 °C), warm (25–30 °C), hot & dry (> 30 °C with low humidity), or hot & humid (> 30 °C with high humidity). Hot and humid raises water needs more than hot alone, because sweat evaporates poorly in humid air, so the body sweats more to shed the same heat. The baseline is 33 mL per kilogram of body weight, adjusted by activity (1.0 sedentary to 1.5 very active) and climate (0.85 cool to 1.30 hot & humid). The result is converted to 8 fl oz cups and fluid ounces. Individual needs vary, and the number is not a medical target.

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