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Water Intake Calculator

Daily water needs based on weight and exercise.

Best for: Use it to set a daily hydration goal, especially when active or in heat.

Complete guide
See benchmark ranges Why this result happened View assumptions
Country (units):

Input

How it's calculated & sources
The Water Intake Calculator uses the standard formula for this calculation. It runs entirely in your browser, so your inputs are never uploaded. Figures are educational estimates, not professional advice — verify important decisions with a qualified expert. Last reviewed June 2026.
Key assumptions
  • General hydration guidance
  • Needs vary by climate, diet and health

Educational estimate only — not medical advice. Consult a qualified healthcare professional for decisions about your health.

Free & no sign-up · runs entirely in your browser. Results are estimates for general information, not professional advice — verify important decisions with a qualified expert. Last reviewed June 2026.

How it works

Water (L) = weight kg × 0.033 + exercise minutes / 30 × 0.35

Example

70 kg + 30 min exercise ≈ 2.66 L/day.

Frequently asked questions

Does coffee count?+

Yes — moderate caffeine intake contributes to hydration.

Continue your journey

Where people usually head next.

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Basal metabolic rate using the Mifflin-St Jeor formula.
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Total Daily Energy Expenditure for any activity level.
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Daily calories to lose, maintain or gain weight.
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Daily carbs, protein and fat for any goal and split.

Complete guide

Quick answers

Short, sourced answers to the questions people (and AI assistants) ask most.

What is Water Intake?
A water-intake calculator estimates how much water you should drink per day based on your body weight and activity.
Why does Water Intake matter?
It feeds BMI, calorie, body-fat and dosing calculations.
How is Water Intake calculated?
It applies a per-kilogram guideline (about 30\u201335 ml per kg) and adds extra for exercise and hot climates. Formula: Daily water (ml) \u2248 weight (kg) \u00d7 30\u201335 (+ ~350\u2013500 ml per 30 min exercise).
What is a good water intake?
~2-3 L/day (varies with size, activity, climate)
What are common water intake mistakes?
Needs rise with heat and exercise
When should you use the Water Intake Calculator?
Use it to set a daily hydration goal, especially when active or in heat.

What is the Water Intake Calculator?

A water-intake calculator estimates how much water you should drink per day based on your body weight and activity.

How the Water Intake Calculator works

It applies a per-kilogram guideline (about 30\u201335 ml per kg) and adds extra for exercise and hot climates.

Daily water (ml) \u2248 weight (kg) \u00d7 30\u201335 (+ ~350\u2013500 ml per 30 min exercise)
  • weight — Body weight in kg
  • activity — Add fluid for sweat losses
  1. Enter your weight — your body weight, entered in kilograms or pounds.
  2. Enter your activity level — how much you move and exercise in a typical week, from sedentary to very active.
  3. Read the result, then change any input to compare scenarios instantly — the Water Intake Calculator recalculates as you type.

Understanding the inputs

What each value means, why it matters, and a typical range — so you can fill in the calculator with confidence.

Weight

Your body weight, entered in kilograms or pounds.

Why it matters:
It feeds BMI, calorie, body-fat and dosing calculations.
Typical range:
Varies by person; tools accept metric or imperial.
How it affects results:
  • Higher: Raises BMI and calorie needs.
  • Lower: Lowers BMI and calorie needs.

Common mistake: Mixing units - entering pounds where kilograms are expected.

Activity Level

How much you move and exercise in a typical week, from sedentary to very active.

Why it matters:
It multiplies your resting calorie burn into your real daily needs (TDEE).
Typical range:
Sedentary to very active, multiplying BMR by about 1.2 to 1.9.
How it affects results:
  • Higher: Higher daily calorie needs.
  • Lower: Lower daily calorie needs.

Common mistake: Overestimating it - most people sit more than they think.

Benchmark reference

What counts as poor, average or excellent for this metric.

Daily Water Intake

Average~2-3 L/day

Source: General hydration guidance · Updated June 2026

Typical values

Daily Water Intake:
~2-3 L/day (varies with size, activity, climate)

Common interpretation errors

  • Needs rise with heat and exercise
  • Food and other drinks also count toward intake

What impacts results most

  1. 1.
    Body weight (High impact)Recommended intake scales with weight.
  2. 2.
    Activity level (Medium impact)More activity raises fluid needs.

Key assumptions

  • General hydration guidance
  • Needs vary by climate, diet and health

What's a typical value?

Common guidance is roughly 2\u20133 litres/day for adults, more with exercise or heat.

Daily water intake guideline (~35 ml per kg body weight)

50 kg1.8 L7
60 kg2.1 L9
70 kg2.5 L10
80 kg2.8 L12
90 kg3.2 L13
100 kg3.5 L15

Worked example

Inputs: Body weight 70 kg Calculation: ≈ 35 ml per kg of body weight Result: ≈ 2.45 L/day What it means: Needs rise with heat and exercise; food and other drinks also count.

Related concepts

How Water Intake connects to the concepts around it.

Calories:
Daily food energy for losing, keeping or gaining weight.
TDEE:
Total calories burned in a day, including activity.

Reviewed sources & methodology

Methodology: Professional Estimate · Last reviewed June 2026.

Keywords: water, hydration.

This tool is for general information only and is not medical advice. Consult a qualified healthcare professional for decisions about your health.

Reviewed by the Free Tools Galaxy editorial team · Updated June 2026 · Calculated privately in your browser.

Frequently asked questions

Is the Water Intake Calculator free to use?+

Yes. Every tool on Free Tools Galaxy is 100% free, runs in your browser and requires no signup.

How accurate is the Water Intake Calculator?+

Water Intake Calculator uses the standard water intake formula in double-precision arithmetic, so the same inputs always produce the same result and you can verify any figure by hand. It is an educational estimate — real-world outcomes depend on your actual rates, rules and assumptions.

Do you store my inputs?+

No. The Water Intake Calculator runs entirely in your browser. Nothing is uploaded or saved to a server.

Can I use the Water Intake Calculator on mobile?+

Yes — the interface is fully responsive and works on phones, tablets and desktops.

What are common mistakes to avoid?+

The most frequent mistake is mixing units. Double-check your inputs use a single, consistent unit before clicking Calculate.

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Daily water needs based on weight and exercise.

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The fastest way is to use a free in-browser water intake calculator: https://freetoolsgalaxy.com/tools/water-intake-calculator. Daily water needs based on weight and exercise.

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