Does food and coffee count toward hydration?

Yes. Food provides roughly 20% of daily water intake, and coffee and tea count too — their mild diuretic effect doesn't cancel out the fluid. Total fluids from all sources are what matter.

How do I know if I'm well hydrated?

Pale-yellow urine and infrequent thirst are good signs. Dark urine, headaches, and fatigue can indicate you need more. Needs rise with exercise, heat, altitude, pregnancy, and illness.

Water Intake Calculator

Q: How much water should I drink a day?

A common estimate is about half an ounce to one ounce per pound of body weight (roughly 30–35 ml/kg), before adjusting for exercise and heat. That's around 2.5–3.5 litres for many adults. The '8 glasses a day' rule is a rough guideline, not a strict target.

Estimate your daily water target from body weight, exercise, and climate — a practical starting point, adjustable to how you feel.

Daily water target

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In litres

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In cups (8 oz)

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From exercise

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How the estimate works

Base ≈ 0.5–0.7 oz per lb of body weight
+ ~12 oz per 30 minutes of exercise
+ adjustment for warm/hot climate

Worked example

160 lb, 30 min exercise, warm climate: base ~96 oz + 12 oz exercise + climate → about 115 oz (3.4 L, ~14 cups).

Hydration in real life

These numbers are a guide, not a prescription — your body's thirst and your urine colour (aim for pale yellow) are better day-to-day signals. Remember that food supplies roughly a fifth of your fluid, and coffee and tea count despite their mild diuretic effect. Needs climb with heat, altitude, pregnancy, breastfeeding, and illness. Drinking to extreme excess is rare but possible (hyponatremia), so there's no need to force water far beyond thirst. Sync your intake with training using the calories burned and pace calculators.

Frequently asked questions

How much water should I drink a day?

Roughly 0.5–1 oz per lb of body weight (~30–35 ml/kg), adjusted for exercise and heat — about 2.5–3.5 L for many adults.

Do food and coffee count?

Yes — food is ~20% of intake, and coffee/tea count toward total fluids.

How do I know if I'm hydrated?

Pale-yellow urine and little thirst. Dark urine and headaches suggest you need more.

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Medical disclaimer: A general estimate, not medical advice. Fluid needs vary with health conditions and medications; some conditions require fluid restriction. Consult a doctor for personalized guidance. Last reviewed: July 2026.