Water Intake Calculator
Suggested daily water intake from body weight and exercise.
Quick answer
- Formula: Water (ml) = weight (kg) × 35 + 350 ml per 30 min of exercise
- Worked example — Water per day: 3.15 litres (full example below).
Water Intake Calculator
| Water per day | 3.15 litres |
| Water per day | 3,150 ml |
| Glasses (250 ml) | 12.6 |
A 70 kg person who exercises for 60 minutes needs about 3,150 ml — 3.15 litres, or roughly 12–13 glasses — per day.
A common weight-based guideline is about 35 ml of water per kilogram of body weight per day for adults under typical conditions. This calculator applies that rule, then adds roughly 350 ml for every 30 minutes of exercise to replace sweat losses.
Needs rise further in heat, at altitude, during illness and in pregnancy, and thirst plus pale-yellow urine remain practical day-to-day guides. This is a general educational estimate, not medical advice — people on fluid restrictions should follow their clinician's guidance instead.
The formula
Worked example
A 70 kg person who exercises for 60 minutes needs about 3,150 ml — 3.15 litres, or roughly 12–13 glasses — per day.
The example is pre-loaded in the result panel — press Calculate with your own numbers to replace it.
Frequently asked questions
Does food count toward this total?
Yes — food typically provides around 20% of daily water, and all drinks count, not just plain water. This calculator's figure is a drinking-water target, so hitting it fully from drinks is comfortably sufficient.
Can you drink too much water?
Yes, though it is uncommon: drinking far beyond thirst for many hours can dilute blood sodium (hyponatraemia). Drink to thirst around the calculated target rather than forcing large volumes.
Category: Health & Fitness calculators
Sources & methodology
This calculator applies the formula shown on this page exactly as written, using the standard definitions for its inputs. Results are computed from the values you enter — no data is stored — and are rounded only for display.
Content last reviewed by CalcHub Editorial.
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