Water Intake Calculator

Written byOleh Soloninupdated 5 October 2026

Body weight, kg

Daily activity, minutes

Climate

Result

Daily target, litres2.56
Daily target, ml2,555
Glasses of 250 ml10.2
Baseline, ml2,100
Added for activity, ml350

This result is informational only and is not professional advice.

Body weight first, then what you add for training and heat

Work out roughly how much water to drink per day from body weight, activity and climate. A starting figure, not a medical rule.

The calculator starts from 30 ml of water per kilogram of body weight: 2.1 litres for someone of 70 kg before any exercise.

Training and heat add to that, and the result is an estimate, not a quota. Some of your fluid comes from food, and thirst and urine colour help check whether you are really getting enough.

How to use

Enter your weight in kilograms.
Enter how many minutes a day you spend exercising.
Choose the climate: temperate, hot or cold.
The result gives litres, millilitres and 250 ml glasses, with the weight baseline and the exercise top-up shown separately.

Water by body weight

The baseline rises by 300 ml for every ten kilograms. Exercise and climate go on top, so with half an hour of exercise in a temperate climate someone of 50 kg needs 1.93 litres and someone of 100 kg 3.5.

Temperate climate. Every row comes from the calculator on this page.
Weight, kg	Baseline, ml	With 30 minutes of exercise, l	250 ml glasses
50	1,500	1.93	7.7
60	1,800	2.24	9
70	2,100	2.56	10.2
80	2,400	2.87	11.5
90	2,700	3.19	12.7
100	3,000	3.5	14

What exercise and heat add

Every half hour of exercise adds 350 ml, about a glass and a half. A hot climate adds 15 percent of the baseline: 315 ml for someone of 70 kg against 105 in a temperate one.

Body weight 70 kg; the climate rows assume 30 minutes of exercise. Every row comes from the calculator on this page.
What changes	Value	Total a day, ml
Exercise	0 minutes	2,205
Exercise	30 minutes	2,555
Exercise	60 minutes	2,905
Exercise	90 minutes	3,255
Climate	cold	2,450
Climate	temperate	2,555
Climate	hot	2,765

What this calculator shows

A daily target in litres, millilitres and 250 ml glasses
The baseline from body weight kept separate from the activity addition
An adjustment for hot or cold climate

What to keep in mind

The baseline is 30 ml per kilogram. On top of that the calculator adds 350 ml for every 30 minutes of exercise, and 15, 5 or 0 percent of the baseline for a hot, temperate or cold climate — its own working assumptions, not measured individual needs.
Kidney, heart and liver conditions change fluid needs substantially — a doctor's advice outranks any calculator.

FAQs

How much water should I drink at 60 kg?

The baseline is 1.8 litres. With half an hour of exercise in a temperate climate the calculator gives 2.24 litres, about nine glasses.

Is eight glasses a day actually right?

It is a rounded slogan, not a calculation. Eight 250 ml glasses is 2 litres — the baseline for someone of about 67 kg, and off for everyone else.

What does EFSA recommend?

The European Food Safety Authority (2010) sets adequate total water intake — from drinks and food together — at 2.0 litres a day for women and 2.5 for men. This calculator works from body weight instead, so it gives lighter people less and heavier people more.

Does tea or coffee count?

Yes. The old claim that caffeine dehydrates you does not hold at normal intakes — the fluid in a cup of coffee still counts toward your day.

How do I tell if I am drinking enough?

Pale straw-coloured urine is the practical check. Dark yellow suggests you are behind; completely clear all day may mean you are overdoing it.

Can you drink too much water?

Yes, though it is rare. Drinking several litres in a short period can dilute blood sodium dangerously, which is why endurance athletes are warned about over-drinking as well as under-drinking.

Worked example

An ordinary day

Input: 70 kg, 30 minutes of exercise, temperate climate

Output: 2.56 litres

Note: Of that, 2.1 litres is the weight baseline, 350 ml covers the exercise and 105 ml is the temperate-climate allowance.

Useful links

All tools in Health calculators for weight, lab values and training

Water Intake Calculator

Result

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