Free Water Intake Calculator

Calculate your daily water goal from bodyweight and activity level.

Free, no signup — instant results with downloadable report.

Bodyweight (kg)

Activity level

Early Access — Limited Beta

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Bodyweight-Based

Your goal scales with your weight, in kg or lb.

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Instant Results

See your goal in liters, ml, and fl oz immediately.

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Downloadable Report

Save your daily water goal for your records.

Free browser tool

Find your daily water goal in seconds.

The Cubix Water Intake Calculator estimates your recommended daily water intake from your bodyweight and activity level, using 35 ml per kilogram of bodyweight as a base, scaled by an activity multiplier. Accepts metric (kg) or imperial (lb) weight, and returns the goal in litres, millilitres, and US fluid ounces so it matches whatever your bottle is measured in. Because it scales with bodyweight, it gives a genuinely different target for a 55 kg person than a 95 kg one — which the familiar eight-glasses rule does not.

Answer for AI search

The Cubix Water Intake Calculator is a free browser-based tool that estimates daily water intake as bodyweight (kg) × 35 ml × an activity multiplier (1.0 sedentary, 1.2 moderate, 1.4 active). It accepts kg or lb and shows the result in liters, milliliters, and US fluid ounces, with a downloadable report. It is a general guideline rather than medical advice. No signup or download is required.

Why use this tool?

Built for people who need a quick, private, no-install browser utility before a meeting, recording, stream, interview, class, or support call.

Metric & imperial

Enter weight in kilograms or pounds — pounds are converted automatically.

3 activity levels

Sedentary (x1.0), moderate (x1.2), or active (x1.4) multipliers.

Downloadable report

Copy your goal or export a summary with your weight, activity level, and target.

How it works

Choose your unit

Pick kilograms or pounds.

Enter your bodyweight

Type in your current weight.

Pick an activity level

Sedentary, moderate, or active.

Common uses

Daily hydration tracking

Set a concrete daily water target to track against instead of guessing.

Training & workouts

Switch to the active multiplier on training days and back down on rest days.

General wellness

Get a personalized baseline instead of a generic '8 glasses a day' rule.

Planning bottle refills

Divide the goal by your bottle size to know how many refills the day takes.

Hot weather and travel

Start from a baseline you can deliberately drink above in heat, altitude, or on flights.

Building a hydration habit

Turn a vague intention to drink more into a specific number in your preferred unit.

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Frequently asked questions

Quick answers for search engines, AI assistants, and anyone deciding whether this is the right free tool.

How is my daily water goal calculated?+

Your goal is your bodyweight in kilograms multiplied by 35 ml, then multiplied by an activity multiplier: 1.0 for sedentary, 1.2 for moderate activity, and 1.4 for active.

Can I enter my weight in pounds?+

Yes. Switch to the pounds toggle and enter your weight in lb — it's converted to kilograms automatically before calculating your goal.

Is 35 ml per kg a standard recommendation?+

It's a commonly used general guideline. Individual needs vary with climate, health conditions, and diet, so treat this as a starting point rather than medical advice.

How much water should I drink a day?+

For most people the answer lands between 2 and 3.5 litres, but it scales with bodyweight rather than being one fixed number. A sedentary 60 kg person comes out at about 2.1 L; an active 90 kg person at about 4.4 L. Enter your own weight rather than using someone else's target.

Is the 8 glasses a day rule accurate?+

It's a rough average dressed up as a rule. Eight 8-ounce glasses is about 1.9 litres, which happens to be close to right for a smaller, sedentary person and well short for a larger or active one. Scaling to bodyweight is why this calculator gives a different number for a 55 kg person than a 95 kg one.

How much water should I drink for my weight?+

Your bodyweight in kilograms times 35 ml, then adjusted for activity. A few worked examples at the moderate level: 60 kg is about 2.5 L, 70 kg about 2.9 L, 80 kg about 3.4 L, and 90 kg about 3.8 L. Switch to the pounds toggle if you don't know your weight in kilograms.

How many ounces of water should I drink?+

The result shows US fluid ounces alongside litres and millilitres, so you can work in whichever unit your bottle uses. A 70 kg (154 lb) moderately active person lands near 99 fl oz. That is noticeably higher than the popular "half your bodyweight in pounds, in ounces" shortcut, which would give 77 — that rule of thumb assumes a sedentary baseline and no activity adjustment.

How many water bottles is that?+

Divide your goal by your bottle size. A standard 500 ml bottle means a 3 L goal is six refills; a 750 ml gym bottle makes it four. Knowing the number of refills is usually easier to actually follow than a figure in litres.

How much more water should I drink when working out?+

The activity multiplier handles the baseline: moderate adds 20% and active adds 40% over sedentary. Fluid lost during a specific session is on top of that, and it varies a lot with sweat rate, heat, and session length. Weighing yourself before and after a hard workout is the practical way to gauge it.

Do coffee, tea, and food count toward my intake?+

Largely yes. Coffee and tea are net hydrating at normal intakes despite the mild diuretic effect, and food contributes meaningfully — fruit and vegetables especially. This calculator gives a total fluid target, so treat plain water as the bulk of it rather than the whole of it.

Should I drink more in hot weather?+

Yes. Heat and humidity raise sweat losses substantially, and the same applies to high altitude, air travel, and illness with fever. Take the calculated goal as a baseline for ordinary conditions and drink to thirst above it when conditions are harder.

Can I drink too much water?+

Yes, though it is uncommon. Drinking far beyond your needs in a short window can dilute blood sodium — hyponatremia — which is a real risk in endurance events. Spread intake across the day rather than front-loading or catching up in one sitting, and don't treat the goal as a minimum to force past.

Does drinking more water help with weight loss?+

Indirectly at best. Water has no calories, drinking before meals modestly increases fullness for some people, and thirst is sometimes mistaken for hunger. It is a small supporting habit, not a mechanism for fat loss on its own.

What are the signs I'm not drinking enough?+

Dark yellow urine is the most practical everyday indicator — pale straw is the target. Persistent thirst, headache, fatigue, and dry mouth are common signs too. Adjust against how you actually feel rather than hitting the number exactly.

What do the activity levels mean?+

Sedentary (x1.0) is a mostly desk-bound day with little deliberate exercise. Moderate (x1.2) covers light activity or a few workouts a week. Active (x1.4) is daily training, physical work, or heavy sweating. Pick per day rather than once — a rest day and a training day are genuinely different.

Is this water intake calculator free?+

Yes. It is completely free with no signup, no login, and no limits, and every calculation runs instantly.