Water Intake Calculator
Get a personalized daily hydration target based on your body weight, training time, and the climate you live in.
Your Stats
Enter your weight to see your daily water target.
What Is Daily Water Intake?
Your daily water intake is the total fluid your body needs to replace what you lose through breathing, sweating, urine, and digestion. About 60 percent of your body is water. Every system you have, from brain to kidneys to muscles, depends on staying topped up.
The classic 8 glasses a day rule is a decent starting point for an average adult, but it ignores body size, training, and climate. The right target for you is personal, and it moves with the seasons.
- • Baseline: about 35 ml per kg of body weight
- • Training: add 500 to 750 ml per hour of exercise
- • Hot climate: add 15 to 30 percent on top
- • Coffee and tea: count toward your daily total
How We Calculate Your Water Target
We use the standard 35 ml per kilogram baseline, then adjust for your training and the climate you live in.
Baseline by Body Weight
We start with 35 ml per kilogram. A 70 kg adult needs around 2.45 liters before any training or heat is added.
Add Training Fluid
Around 12 ml per minute of training covers the sweat losses for moderate intensity. Hot conditions push that higher.
Adjust for Climate
Hot or humid environments raise needs by 15 to 30 percent. Cold dry winter air also dehydrates more than people expect.
Factors That Change Your Water Needs
Your daily target is not fixed. These are the variables that move it up or down across the year.
Body Weight and Size
More body mass means more cells to hydrate and more skin to lose water through. Bigger bodies need more fluid.
Training and Sweat Rate
Hard workouts can produce 0.5 to 2 liters of sweat per hour. Heavy sweaters need more, and electrolytes too.
Climate and Altitude
Hot and humid weather raises needs by 15 to 30 percent. Higher altitudes increase fluid loss through breathing.
Diet Composition
High protein and high salt diets increase water needs. Fruit, vegetables, and soup add hidden water back in.
Caffeine and Alcohol
Caffeine is mildly diuretic but mostly cancels out. Alcohol is strongly dehydrating, plan to add a glass of water per drink.
Air Conditioning and Heating
Indoor environments dry the air, which increases fluid loss through breathing and skin without you noticing.
Tips To Hit Your Water Target
- 1
Start with a Glass on Waking
After 7 to 9 hours without water, your body is mildly dehydrated. A big glass before coffee fixes it.
- 2
Drink Before Each Meal
A glass 15 minutes before meals helps with hunger control and stacks easy wins toward your daily total.
- 3
Use a Reusable Bottle
A 750 ml or 1 liter bottle on your desk turns hydration into a visual reminder. Refill twice and you are most of the way there.
- 4
Hydrate Around Training
500 ml in the hour before, 250 ml every 20 minutes during, and 500 ml in the hour after. Add electrolytes for sessions over an hour.
- 5
Eat Your Water Too
Cucumber, watermelon, oranges, soups, and yogurt all add fluid without feeling like you are drinking it.
- 6
Taper Before Bed
Stop drinking 90 minutes before sleep so you are not waking up to use the bathroom. Quality of sleep beats one extra glass.
Water Intake FAQ
Quick answers to the questions people ask most.