Health & Fitness
Find your daily hydration target based on weight and activity level.
Daily water intake
2.8L
2,800 ml or 11.7 cups
Formula: (weight in kg × 35 ml) + (exercise minutes ÷ 30 × 350 ml). Adjust based on climate, diet, and individual needs.
A water intake calculator is a tool that estimates how much water you should drink daily based on factors like body weight, exercise frequency, climate, and pregnancy status. It applies evidence-based hydration formulas to account for your unique physiology and lifestyle, helping you avoid both under-hydration and excessive fluid intake.
The calculator starts with a baseline formula—typically 30-35 millilitres per kilogram of body weight—then adjusts for modifying factors. If you exercise regularly, you add water to compensate for sweat loss (0.5–1 litre per hour of activity). Hot climates increase baseline needs; pregnancy and breastfeeding raise requirements further. The tool sums these factors to deliver a personalized daily target in litres or cups.
Daily Water Intake (ml) = (Body Weight in kg × 35) + (Exercise Duration in minutes × 0.5) + Climate/Health AdjustmentsBody weight is the primary driver: heavier bodies need more water. Exercise adds 0.5 ml per minute of activity (e.g., 30 minutes = 15 ml extra). Climate adjustments add 500–1000 ml in hot conditions; pregnancy adds 300 ml; breastfeeding adds 700 ml daily.
| Input | Result | Notes |
|---|---|---|
| 70 kg person, sedentary, temperate climate | 2.45 litres per day (≈10 cups) | Baseline hydration for an office worker with no intensive sweating |
| 85 kg person, 45 minutes gym daily, hot climate | 3.5–4 litres per day (≈14–16 cups) | Exercise and heat significantly increase fluid losses; higher baseline needed |
| 65 kg breastfeeding mother, light activity | 3.2 litres per day (≈12–13 cups) | Lactation increases requirement by 700 ml above standard baseline |
No. The '8×8' rule is a rough average, not a science-based standard. A 50 kg person sedentary in winter needs ~1.75 litres; an 100 kg athlete in summer may need 4+ litres. This calculator accounts for your specific body and context.
Yes, partly. About 20% of daily hydration typically comes from food (watermelon ~92% water, lettuce ~95%). However, this calculator focuses on drinking water; you can reduce your drinking target by 300–500 ml if you eat a very high-water-content diet.
Yes. Hyponatraemia (dangerously low blood sodium) can occur if you drink >3–4 litres of plain water in a short period with no electrolytes. Endurance athletes and people with certain medical conditions are at higher risk. Drink to thirst and include electrolytes in longer workouts.
Both have mild diuretic effects, so they don't replace plain water. A cup of coffee (~100 mg caffeine) causes modest extra urine loss. The safe rule: add 150–200 ml drinking water per caffeinated drink or alcoholic unit.
Pregnant women have expanded blood volume, amniotic fluid production, and higher metabolic rate. An extra 300 ml daily (2-3 glasses) supports placental function and prevents constipation, which is common in pregnancy.
Absolutely. Fever and diarrhoea cause significant fluid loss. Add 500 ml–1 litre to your baseline target. If you have persistent diarrhoea or vomiting, use oral rehydration solution (WHO formula) instead of plain water to replace lost electrolytes.