Daily Water Intake Calculator
A practical hydration target based on your body weight, exercise time and climate. Built for hikers who want to plan water, not guess it.
General information, not a diagnosis or treatment plan. Do not change medication, diet or training based on this result — discuss it with a qualified healthcare professional. Read the full disclaimer.
Your daily water target
Daily targetAbout 3.1 L a day — roughly 12 glasses of 250 ml.
What to pay attention to
- Start the day with 500 ml of water before coffee or breakfast.
- On the trail, sip 150–250 ml every 20–30 minutes instead of one big drink at lunch.
- Pale straw-coloured urine is a practical hydration check.
- Cold weather and altitude dry you out through breathing — drink even when not thirsty.
- Never ration water on a hike. Turn back early if your supply runs low.
- Most people absorb about 0.8–1 L per hour at most. Drinking far beyond thirst on a long day can dilute sodium — include electrolytes and salty food.
Educational estimate only — not medical advice. Talk to a healthcare professional before changing your diet, training or medication.
A day of hydration
- 1On waking500 ml
Before coffee or breakfast.
- 21–2 h before a hike400–600 ml
Start hydrated, not catching up.
- 3Every 20–30 min on trail150–250 ml
Small sips beat one big chug.
- 4After the hike500 ml + food
Replace what you lost; add electrolytes for 3 h+ days.
- 5EveningRemaining of the day
Aim to finish near your daily target.
Why hydration matters on the trail
Losing just 2% of body weight in water can reduce hiking performance and increase perceived effort. In cold weather and at altitude you lose water through breathing without feeling thirsty, which makes dehydration easy to miss.
Do not ration water to make it last. If you are down to half your supply before the halfway point, turn back.
More is not always better. Drinking far beyond thirst — especially plain water on a long, hot day — can dilute the sodium in your blood (hyponatremia). On outings over three hours, or when you sweat heavily, include electrolytes and salty food and let thirst guide you rather than forcing a fixed volume.