Water Intake Calculator
Enter your weight and how much you exercise to estimate how much water to aim for each day — a simple, personalized target in ounces, cups and litres.
Quick answer: A common guide is to drink about half your body weight in ounces of water a day, plus roughly 12 oz for every 30 minutes of exercise. For a 160 lb person that's around 92 oz (2.7 L). On creatine, add about 16–24 oz extra to stay well hydrated.
A popular rule of thumb is to drink about half your body weight in ounces of water each day, then add a bit more for exercise. It's a simple starting point — food and other drinks also count toward your total fluids.
How the water intake estimate works
Take half your body weight in pounds as a number of ounces, then add roughly 12 ounces for every 30 minutes of exercise.
Base (oz) = Body weight (lb) × 0.5
Exercise (oz) = Minutes ÷ 30 × 12
Daily target = Base + Exercise
Exercise (oz) = Minutes ÷ 30 × 12
Daily target = Base + Exercise
| Factor | Effect on needs |
|---|---|
| Exercise | Add ~12 oz (350 ml) per 30 minutes |
| Hot or humid weather | Increases needs through sweat |
| Pregnancy / breastfeeding | Higher fluid requirements |
| Illness (fever, vomiting) | Replace extra lost fluids |
Worked example
A 160 lb person doing 30 minutes of exercise:
| Base = 160 × 0.5 | 80 oz |
| Exercise = 30 ÷ 30 × 12 | 12 oz |
| Daily target | ≈ 92 oz (about 2.7 L) |
Frequently asked questions
How much water should I drink a day?
A common guide is about half your body weight in ounces, plus more for exercise and heat. For many adults that lands somewhere around 2–3.5 litres of total fluids per day.
Do coffee and food count?
Yes. Most drinks and water-rich foods contribute to your daily fluids, so you don't need to hit the whole target from plain water alone.
Can you drink too much water?
Rarely, but yes — drinking very large amounts in a short time can dangerously dilute blood sodium. Spread intake through the day and drink to thirst.
How much water should I drink on creatine?
Creatine draws water into your muscles, so add extra fluid — roughly 16–24 oz (0.5–0.7 L) above your normal target while supplementing, and more on training days. Aim for pale-yellow urine as a hydration check.
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For general information only — not medical advice. Fluid needs vary with health conditions and medications. Ask a healthcare professional about your personal needs.