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Find out how much water you should drink per day. Free water intake calculator uses your weight, activity level and climate to recommend daily hydration in cups, ounces or liters.
Affects baseline fluid recommendations
Enter in lbs or kg; used to tailor your daily water intake
More activity means higher water needs
Hot weather increases how much water you need
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The Water Intake Calculator helps you see how much water you should drink per day based on your weight, sex, activity level, and climate. Get a daily water recommendation in cups, ounces, or liters. Recommendations follow general guidelines from health authorities and are adjusted for activity and climate so they fit your lifestyle.
Daily water intake isn't one number for everyone. The calculator gives you a personalized target so you can stay hydrated without guessing. Use it to check whether you're in the right range, then rely on thirst and how you feel. We also show your result in glasses and common bottle sizes so it's easy to apply.
The tool is free and works in pounds or kilograms. For more on hydration and the science behind "how much water per day," see our blog post linked below.
Read more: How Much Water Should You Drink a Day? Or try our Sleep Debt Calculator or Steps to Burn Pizza.
Our calculator uses proven formulas and up-to-date data to give you accurate results. Here's a transparent look at the methodology behind your calculation.
The Formula
Baseline fluids from guidelines: ~2.56 L (average), ~2.96 L (male), ~2.16 L (female) from drinks (about 80% of total fluid AI)Weight scale: baseline × (your weight in kg / 70), capped between 0.7 and 1.5 so very light/heavy don’t go extremeActivity multiplier: sedentary 1.0, light 1.1, moderate 1.25, very active 1.4Climate multiplier: temperate 1.0, hot/humid 1.2, cold 0.9Daily water intake = baseline × weight scale × activity × climateWe start from sex-based adequate intake (beverages only), scale by your weight (70 kg reference), then multiply by activity and climate. Results are in liters and converted to cups, oz, and bottle counts.
Your weight (and unit), sex, activity level, and climate set the baseline and adjustments.
We use sex-based beverage guidelines, scale by your weight (70 kg reference), then multiply by activity and climate to get your daily water intake.
The calculator shows how much water to drink per day in cups, oz, liters, and bottle equivalents.
Disclaimer: Results are estimates based on the information provided. For professional advice, consult with a qualified expert in the relevant field. This calculator is for informational purposes only.