70 kg, no exercise
- Input
- Weight = 70 kg, Exercise = 0 min
- Working
- 70 × 35 = 2,450 ml = 2.45 litres. In cups: 2,450 ÷ 240 = 10.2 cups.
- Result
- 2,450 ml = 2.45 litres ≈ 10.2 cups
Water Intake Calculator
Work out a daily water figure from the 35 ml per kilogram rule of thumb, with an exercise addition and conversions to litres, cups and fluid ounces. Runs entirely in your browser — your numbers never leave this device.
Weight unit
Daily water intake
2.45 L
litres per day
- Millilitres
- 2,450
- Cups (240 ml)
- 10.21
- US fl oz
- 82.84
- Glasses (250 ml)
- 9.8
The calculation is a rule of thumb: 35 ml per kg of body weight, plus 355 ml per 30 minutes of exercise. Needs vary with climate, diet and individual factors.
Informational only. This calculator applies a published formula to the numbers you enter — it is not medical advice, a diagnosis, or a substitute for a clinician. Talk to a qualified professional about decisions concerning your health.
How it works
Rule of thumb used on this page: daily water = 35 ml × body weight (kg) + 355 ml per 30 minutes of exercise
| Basis | Amount |
|---|---|
| Body weight | 35 ml per kg |
| Exercise | +355 ml per 30 min |
| 1 cup | 240 ml |
| 1 fl oz | 29.57 ml |
This calculator applies a widely used rule of thumb: 35 millilitres of water per kilogram of body weight per day, plus 355 millilitres for each 30 minutes of exercise. The rule is printed in full in the formula above because rules of thumb for water vary — other published guides use different per-kilogram figures — and a result can only be judged against the rule that produced it.
The figure the rule returns is a guide figure, not guidance. Actual water needs vary with climate, diet and individual factors, and water also arrives in food and other drinks, none of which a per-kilogram rule models. The page therefore presents the arithmetic and its conversions — into litres, cups at 240 ml and fluid ounces at 29.57 ml — without attaching an instruction to the number.
All calculation runs in the browser. Body weight and exercise time are never uploaded or stored.
Worked examples
80 kg with 60 minutes of exercise
- Input
- Weight = 80 kg, Exercise = 60 min
- Working
- Base: 80 × 35 = 2,800 ml. Exercise: 2 × 355 = 710 ml. Total = 2,800 + 710 = 3,510 ml = 3.51 litres.
- Result
- 3,510 ml = 3.51 litres
60 kg with 30 minutes of exercise
- Input
- Weight = 60 kg, Exercise = 30 min
- Working
- Base: 60 × 35 = 2,100 ml. Exercise: 355 ml. Total = 2,100 + 355 = 2,455 ml ≈ 2.46 litres.
- Result
- 2,455 ml ≈ 2.46 litres
Frequently asked questions
Which rule does this calculator use?
The rule printed on this page: 35 ml per kilogram of body weight per day, plus 355 ml per 30 minutes of exercise. Other guides use different figures; the rule is stated so the result can be compared on equal terms.
Is the result the amount a person needs?
It is the output of a rule of thumb, presented as a guide figure for information only. Actual needs vary with climate, diet and individual factors. The page does not present the figure as medical or dietary guidance.
How many cups is a litre on this page?
The conversion table on this page uses 240 ml per cup, so a litre is 1,000 ÷ 240 = about 4.2 cups. The worked examples use the same 240 ml cup.
Does the exercise addition scale with time?
Yes, in the rule as stated: 355 ml for each 30 minutes, so 60 minutes adds 710 ml, as the second worked example shows.
Are entries stored?
No. The calculation runs entirely in the browser and nothing entered is uploaded, stored or tracked.
Related tools
BMR & Calorie Calculator (TDEE)♥Estimate basal metabolic rate with the Mifflin-St Jeor equation and scale it to total daily energy expenditure with the standard activity factors.Open tool →Macro Calculator♥Split a calorie total into protein, carbohydrate and fat grams for five named presets, using the standard 4, 4 and 9 kcal per gram conversion.Open tool →Calories Burned Calculator♥Estimate energy expenditure for common activities from body weight and duration, using MET values from the published Compendium of Physical Activities.Open tool →BMI Calculator♥Calculate body mass index from weight and height using the WHO formula, in metric or imperial, and locate the result in the published WHO bands.Open tool →Sleep Calculator♥Work out bedtimes and wake times in complete 90-minute sleep cycles, with an adjustable allowance for the time taken to fall asleep.Open tool →Unit Converter⇄Convert between metric and imperial units across length, weight, temperature, volume and more — with exact defined factors, in your browser.Open tool →
More in Health & Body Calculators · Browse all tools