Health and fitness tools
Water Intake Calculator
Estimate a daily water intake target from your body weight and exercise minutes in millilitres, litres, cups, and fluid ounces locally in your browser.
Estimate a daily water target from your body weight and optional exercise minutes. The baseline uses 35 ml per kilogram of body weight, and exercise adds about 500 ml for every 30 minutes. Calculations run locally in your browser; your values are not uploaded or stored.
Estimate a daily hydration target from weight and activity.
Enter your body weight in kilograms or pounds and, optionally, how many minutes you exercise per day. The baseline uses 35 ml of water per kilogram of body weight, and exercise adds about 500 ml for every 30 minutes. For example, a 70 kg person who exercises 30 minutes gets 2450 ml baseline plus 500 ml for exercise, a total of 2950 ml (2.95 L, about 12.5 US cups or 99.8 fluid ounces). A blank exercise field is treated as zero. Food typically supplies about 20% of daily water, so treat the result as total fluid intake and adjust for heat, illness, pregnancy, and activity. This is a general estimate, not medical advice. Your values are calculated locally and are not uploaded or stored.
Frequently Asked Questions
Everything you need to know about this tool, how it works, and privacy.
How does the water intake calculator work?
It estimates a baseline of 35 ml of water per kilogram of body weight, then adds about 500 ml for every 30 minutes of exercise you enter. For example, a 70 kg person who exercises 30 minutes gets a 2450 ml baseline plus 500 ml, a total of 2950 ml (2.95 L). The result is also shown in US cups and fluid ounces.
How much water should I drink each day?
There is no single number that fits everyone. Common guidance is roughly 35 ml per kilogram of body weight (about half an ounce per pound) as total fluids, with more during exercise, hot weather, illness, pregnancy, or breastfeeding. Use the estimate as a starting point and let thirst and urine colour guide you, and follow medical advice if you have heart, kidney, or fluid-balance conditions.
Which inputs are accepted?
Enter a body weight from 20 kg to 500 kg (about 44 lb to 1102 lb) and optional exercise minutes from 0 to 600 per day. A blank exercise field is treated as zero. Missing, non-numeric, or out-of-range entries show a clear error instead of a result.
Does food count toward daily water intake?
Yes. Food usually supplies roughly 20% of daily water, and all drinks count too, including tea, coffee, and milk. The result here is an estimate of total fluid intake, so you do not need to drink every millilitre as plain water.
Is this medical advice?
No. It is a general estimate based on body weight and activity, not a diagnosis or a personal prescription. Needs vary with health conditions, medications, climate, altitude, pregnancy, and breastfeeding. Discuss personal hydration questions with a qualified healthcare professional. Your values are calculated and copied locally in your browser, not uploaded or stored.