Daily water intake estimator

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See a basic daily water figure from adult reference values, split into water from drinks and from food, then add extra for sweat lost during exercise or work outdoors.

Sex Female Male

Most of today's conditions Normal temperature or air-conditioned Hot weather or long hours outdoors

Exercise or sweaty work (minutes per day)

min

No exercise? Enter 0 or leave blank

If you weighed yourself before and after exercise (optional)

Use the same scale and the same dry clothes, and towel off before weighing. Add any water drunk and urine passed during exercise if you know them. This replaces the time-based estimate

Weight before

Weight after

Water drunk during

Urine during

Which applies to you?

What you enter is calculated in your browser only. It is not sent to a server, not stored, and disappears when you close the page.

What the result means

Your body gets water from all drinks (water, milk, tea, coffee, soup) and from food such as vegetables, fruit and rice. Reference values are for total water, of which about 20% usually comes from food and the rest from drinks.

EFSA sets adequate intakes of total water for adults at 2.0 L a day for women and 2.5 L for men, at moderate temperature and activity. Older adults use the same values; add 300 mL in pregnancy and 700 mL when breastfeeding.

Exercise and hot weather increase sweat losses, so this tool shows the extra separately instead of using a body-weight-times-a-constant formula, which ignores climate and activity.

How it is calculated

Total water = EFSA adequate intake (women 2.0, men 2.5 L) + 0.3 L in pregnancy or 0.7 L when breastfeeding
From drinks ≈ 80% and from food ≈ 20% (IOM 2005: about 19% from food in US intake data) · shown in 250 mL glasses
Part 3 (sweat): if you weighed yourself, sweat = weight before − after + water drunk during − urine during (ACSM 2007) · net fluid loss not yet replaced = the weight lost (before − after), because water drunk during activity has already replaced the rest and urine is already reflected in your weight · same or higher weight = no net fluid loss found (not "no sweat") · without weighing, time × 0.3–1.2 L per hour (IOM 2005)
Replacement is spread out at no more than about 1 L per hour, in line with how fast the stomach passes on fluid (IOM 2005: 1.0–1.5 L per hour)
Body weight is not used for the baseline

Limitations and cautions

Reference values for healthy people, not an amount you must reach every day; real needs depend on climate, activity, diet and your body
Sweat rates vary widely, so the time-based range is broad. Weighing before and after is more accurate but still affected by the scale, clothing and anything eaten or drunk that you did not record
Not for children under 14 or anyone told by a doctor to limit fluids (e.g. kidney, heart or liver disease)
This tool does not recommend drinks or products

Results are estimates or basic screening only, not a medical diagnosis or medical advice.

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References

Compiled by Well Nutrition Hub from the sources listed. Content last reviewed 16 Oct 2026.