Water Intake Formula Calculator
Explore a simplified water-intake formula; the result is not an individualized hydration recommendation.
Formula and sources updated · Data sources · 1View algorithm, constants and default inputs (JSON)
About this calculator
This is an adjustable arithmetic scenario, not a personal hydration recommendation. It uses 35 ml/kg as a baseline, adds 350 ml per 30 minutes of exercise, then applies a selected climate multiplier. It does not distinguish drinking water from other beverages or food moisture, and needs vary with activity, environment, health and other factors. Follow clinical guidance when you have a fluid restriction or health condition.
Worked example
calculated with the default values below
Body weight 70 kg · Exercise per day 30 min · Climate Temperate Water per day 2.80 L · Glasses (250 ml) 11.2 glasses · Millilitres per kg 40.0 ml/kg
Method and assumptions
V = (35 × m + 350 × t ÷ 30) × k ÷ 1000 Arithmetic scenario V=(35m+350t/30)k ml; glasses=V/250; ml/kg=V/m. These coefficients are user-facing assumptions, not a recommended intake. This is an adjustable arithmetic scenario, not a personal hydration recommendation. It uses 35 ml/kg as a baseline, adds 350 ml per 30 minutes of exercise, then applies a selected climate multiplier. It does not distinguish drinking water from other beverages or food moisture, and needs vary with activity, environment, health and other factors. Follow clinical guidance when you have a fluid restriction or health condition. The references provide context and limitations. They do not validate this page’s illustrative multipliers, lookup values or predictions.
Data sources
The references provide context and limitations. They do not validate this page’s illustrative multipliers, lookup values or predictions.
Disclaimer
These calculators are for general information only and are not a medical device, a diagnosis or a treatment plan. Reference ranges describe populations, not individuals, and do not account for pregnancy, medication, disability or athletic training. Discuss your own situation with a qualified healthcare professional.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
V = (35 × m + 350 × t ÷ 30) × k ÷ 1000
- m
- Body weight (kg)
- t
- Exercise (min/day)
- k
- Climate factor 1 / 1.1 / 1.2
- V
- Daily water (liters)
Arithmetic scenario V=(35m+350t/30)k ml; glasses=V/250; ml/kg=V/m. These coefficients are user-facing assumptions, not a recommended intake.
Frequently asked questions
Is the result a recommended amount to drink?
No. It is only the entered formula: 35 ml/kg, plus 350 ml per 30 minutes of exercise, multiplied by the selected climate factor. It does not account for water from all foods and beverages or individual health needs. The National Academies notes that water needs vary and its reference values describe total water from food and beverages as well as drinking water. Follow a clinician’s advice for medical conditions or fluid limits. [National Academies water DRI](https://nap.nationalacademies.org/read/10925/chapter/2).
Which inputs and limits apply to Water Intake Formula Calculator?
Use the units shown beside each field. These are form limits, not recommended settings. Body weight: 20–400 kg; Exercise per day: 0–600 min V = (35 × m + 350 × t ÷ 30) × k ÷ 1000 Arithmetic scenario V=(35m+350t/30)k ml; glasses=V/250; ml/kg=V/m. These coefficients are user-facing assumptions, not a recommended intake. This is an adjustable arithmetic scenario, not a personal hydration recommendation. It uses 35 ml/kg as a baseline, adds 350 ml per 30 minutes of exercise, then applies a selected climate multiplier. It does not distinguish drinking water from other beverages or food moisture, and needs vary with activity, environment, health and other factors. Follow clinical guidance when you have a fluid restriction or health condition. The references provide context and limitations. They do not validate this page’s illustrative multipliers, lookup values or predictions.
What is a complete worked example for Body weight = 70 kg; Exercise per day = 30 min?
Inputs: Body weight = 70 kg; Exercise per day = 30 min; Climate = Temperate. Calculation: V = (35 × m + 350 × t ÷ 30) × k ÷ 1000. Results: Water per day = 2.80 L; Glasses (250 ml) = 11.2 glasses; Millilitres per kg = 40.0 ml/kg.