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Weight, training, climate

Eight glasses, and the sentence that got lost.

In 1945 a US board suggested around two and a half litres a day, and added that most of it is already present in prepared food. The second half fell off somewhere on the way to the fridge magnet. Here is a baseline that knows your weight.

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Litres, the eight glasses rule

Eight glasses of eight ounces, the same for everyone, in every climate, whether or not they trained that day.

The old rule
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You
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0Glasses of 250 ml
0From weight
0Added

The arithmetic runs in your browser. Nothing is sent anywhere.

Method
About 32.5 ml per kg of bodyweight, plus roughly 350 ml for every 30 minutes of exercise, plus an allowance for heat. The blog calculators use the same starting figure.
Limits
Thirst still outranks any formula, and so does the colour of your urine. Kidney and heart conditions change this completely. Drinking far beyond thirst is not safer, it is its own risk.

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