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Water Intake Calculator
Estimate how much water and other beverages to drink each day, based on your weight and exercise.
Your daily beverage estimate
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Change the example inputs to calculate.
See the formula and limitations below.
Turn a starting goal into a daily habit. Log water in one tap and get reminders on your schedule.
Track your daily goal with AquaJoy ↗Free download · iPhone · No account neededHow to use the water intake calculator
- Enter your body weight in kilograms or pounds.
- Choose how many minutes you exercise on this day.
- Read your estimated daily beverages in liters, US fluid ounces and 250 mL glasses.
The filled-in values are examples. Change them to see your own estimate. This tool is intended for generally healthy adults, not children or people with prescribed fluid limits.
How much water should I drink by weight?
Body weight is a useful starting point, but it cannot capture your whole day. Temperature, food, medications and how much you sweat can all change your needs. This calculator gives a range for beverages, rather than claiming one exact amount of plain water.
For example, at 70 kg with no exercise, the estimate is 1.68–1.96 L of beverages per day. At 60 minutes of exercise, it is 2.08–2.76 L. Tea, coffee and other drinks count toward that beverage total; it is not all extra water to drink on top of them.
Formula and assumptions
Daily beverages (mL) ≈ weight (kg) × 30–35 × 0.8 + exercise (hours) × 400–800.
The weight-based range comes from NICE guidance for adult nutrition support. That is a clinical context, not a validated personalized drinking-water formula. AquaJoy uses it only as a rough planning heuristic. We estimate an 80% beverage share because food often contributes around 20% of total water; your diet can differ.
The exercise addition is a broad 0.4–0.8 L per hour planning band discussed in ACSM guidance. It is not a measurement of your sweat loss, and may overestimate or underestimate your needs. For a measured exercise estimate, use the sweat rate calculator.
Use the estimate as a starting point
Choose a realistic water-only goal after accounting for your other drinks, then adjust with thirst, your routine and professional advice when needed. Do not force yourself to finish a calculated amount. People who are pregnant, breastfeeding, older or frail, or have kidney or heart conditions need individual guidance. This tool does not account for those situations.
Read our guide to how much water to drink a day and building a hydration habit.
Frequently asked questions
How much water should I drink a day?
There is no single amount that fits everyone. This calculator estimates beverages using weight and exercise. Water in food and other drinks also contributes to hydration, so the result is not a required amount of plain water.
Is this water intake calculator accurate?
The arithmetic follows the formula shown, but the formula is a rough planning estimate. It cannot measure your personal needs or account for climate, diet, health conditions and individual sweat loss.
Do coffee and tea count toward water intake?
Yes. Coffee, tea and other beverages contribute fluid. Account for them before treating the estimate as a water-only goal.
How many glasses of water is that?
We divide the estimated beverage volume by 250 mL to show a familiar glass size. Your glass may be a different size. A US measuring cup is approximately 237 mL.
Can I drink too much water?
Yes. Excessive drinking can lower blood sodium, especially during prolonged exercise. Do not treat this estimate as an amount you must force yourself to drink.
Can I track my goal in AquaJoy?
Yes. AquaJoy lets you set a daily water goal, log drinks and receive reminders on iPhone. Choose your goal in the app after considering your other beverages; this calculator does not automatically set it.
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Sources and method
By Bruno Martins, creator of AquaJoy. Updated October 8, 2026. Informational tool; not a substitute for professional advice.