Water Intake Calculator

How Water Intake Calculator works

Estimate a daily water target from body weight and exercise minutes. The common guide is 33 ml per kilogram plus extra for exercise; this tool applies both. Everything happens inside this page: the tool reads your input, runs the calculation or conversion locally, and hands the result back to you. Nothing is transmitted, because there is no backend to transmit it to.

That design choice is deliberate. Most free tool sites upload your files to a server, process them there, and quietly keep a copy. Toolcin cannot do that — the site is a set of static files. If your connection dropped the moment the page finished loading, every tool would still work.

Thirty-three millilitres per kilogram

The common guide is 33 ml of water per kilogram of body weight, plus extra for exercise. At 70 kg that is about 2.3 litres a day before activity.

It is a population rule of thumb, not a measurement: needs vary with climate, diet, medication and individual physiology, and food contributes roughly 20% of total water intake for most people.

What the number does not include

Coffee and tea count toward fluid intake despite the diuretic myth — the net effect is still hydration. Alcohol is the exception, since it increases loss.

Hot climates and high altitude raise the requirement substantially, and the calculator's exercise field does not model temperature.

When to ignore it

Kidney, heart and liver conditions often require fluid restriction, and in those cases a generic calculator is actively unhelpful. Follow clinical advice instead.

Good to know

• Works offline once loaded, including on flights and in locked-down networks.
• No file size limit beyond your device's own memory.
• Free to use, with no account and no usage counter.
• Results are produced locally, so they are not logged or shared with anyone.

Questions

How this number is produced

The calculation is 33 ml of water per kilogram of body weight, plus an allowance per 30 minutes of exercise, following a common hydration rule of thumb, not a clinical guideline. The formula is repeated here so the result can be checked by hand rather than taken on trust.

This is a calculator, not advice. No clinician, accountant or adviser has reviewed it, and it cannot see your circumstances. For anything involving health, a loan, a tax filing or a religious obligation, confirm the figure with a qualified professional or the authority that publishes the rule.