HydroPlan

Water Intake Calculator

Your daily hydration target, tailored to your weight, activity level, and climate.

Body weight (kg)

Activity level

Climate

Daily water target

2.94 L

Fluid ounces: 99 fl oz
8 oz cups: 12.3 cups

What you entered

Body weight: 75 kgActivity: moderateClimate: temperate

1
Baseline: 35 mL per kg of body weight
75 × 35= 2625 mL
2
Adjust for activity level
2625 × 1.12= 2940 mL
3
Adjust for climate
2940 × 1= 2940 mL

Result

Daily water target: 2.94 L

Based on your weight, activity level, and climate, aim for about 2.94 litres (12.3 cups) of water per day — this is a baseline, not a hard limit, and thirst plus urine color are still the best day-to-day guides.

Daily water target by body weight, activity, and climate

Baseline is 35 mL per kilogram of body weight, multiplied by activity (1.00 low, 1.12 moderate, 1.25 high) and climate (1.00 temperate, 1.10 hot or humid). The first three litre columns assume a temperate climate; the fourth combines high activity with a hot one.

Body weight	Low activity (L)	Moderate activity (L)	High activity, hot climate (L)	Moderate activity (fl oz)
50 kg / 110 lb	1.75	1.96	2.41	66
60 kg / 132 lb	2.10	2.35	2.89	80
70 kg / 154 lb	2.45	2.74	3.37	93
80 kg / 176 lb	2.80	3.14	3.85	106
90 kg / 198 lb	3.15	3.53	4.33	119
100 kg / 220 lb	3.50	3.92	4.81	133
110 kg / 243 lb	3.85	4.31	5.29	146

These are total fluid targets, and roughly 20 percent of daily hydration normally comes from food, so the amount you need to drink is lower than the figure shown. Coffee and tea count toward it. Add another 500 to 1,000 mL per hour of hard exercise on top. Urine colour is a better day-to-day guide than any formula. Do not force very large volumes quickly: drinking far past thirst during long endurance events can cause dangerously low blood sodium.

Beyond plain water

About 20% of daily hydration comes from food, especially fruit, vegetables, and soups. Coffee and tea count toward your total despite their mild diuretic effect.

Signs of dehydration

Dark yellow urine is the most reliable everyday indicator. Other signs: headaches, fatigue, dizziness, dry mouth, and reduced concentration. By the time you feel thirsty, you're already mildly dehydrated. During exercise, a 2% body weight loss from sweat noticeably impairs performance.

Frequently asked questions

How much water should I drink per day?

The general guideline is about 35 mL per kg of body weight — roughly 2.5 L (84 oz) for a 70 kg person. Active people in hot climates need more: add 500–1000 mL per hour of exercise. The 8-glasses-a-day rule (2 L) is a reasonable minimum but may not be enough for larger or active people.

Does coffee count toward water intake?

Yes. While caffeine has a mild diuretic effect, the net hydration from coffee and tea is still positive — you retain most of the water. A cup of coffee is roughly equivalent to 0.8 cups of water for hydration purposes. Only very high caffeine doses (>500 mg/day) meaningfully increase fluid loss.

Can you drink too much water?

Yes — hyponatremia (dangerously low blood sodium) can occur from drinking excessive water, especially during prolonged exercise. Symptoms: nausea, headache, confusion. It's rare in daily life but happens in endurance events. Drink to thirst and replace electrolytes during exercise lasting over an hour.