How many oz of water should i have a day

Water is the most underutilized tool when it comes to your health. From hydrating skin and helping with headaches to giving you an endless supply of energy, simply drinking enough H2O each day can pay off in a big way.

But how much should you be drinking? Traditional recommendations about water intake aren't so cookie cutter anymore, says Jaclyn London, MS, RD, CDN, NYC-based registered dietitian, author of Dressing on the Side (and Other Diet Myths Debunked): 11 Science-Based Ways to Eat More, Stress Less and Feel Great About Your Bodyand host of the podcast On the Side with Jackie London, RD. "Typically, I'd recommend drinking around 8 cups of H2O per day — but I use that metric as a very general place to start, since many of us will need more or less depending on where we live, how physically active we are, medications we're taking and our current activities of daily living," London says.

There's also a new lifestyle factor London's been taking into consideration when offering advice. "I've also found myself recommending people who are working from home to increase their fluid intake if they're on back-to-back calls. Why? Because not only do we lose water through our GI and urinary tracts, we also lose it through our respiratory tract—so more talking equals the need for more hydrating!" London adds.

And when it comes to upping hydration, it doesn't just have to be plain H20. "I'm often giving the advice to consider where you can add a cup or two of extra unsweetened beverages to your day — sparkling water, diet beverages, unsweetened coffee and tea also 'count' toward your daily hydration goals," says London.

How to know if you're getting enough? Though the amount of water a person needs varies much like calories, you can make a guesstimate based on a few different factors. Read on to calculate how much water you should be drinking each day based on your own unique needs.

How much water should you drink every day?

Women should generally drink about 9 cups of fluids a day, while men should aim for 12, according to the Mayo Clinic. That's 72 ounces for us ladies. Where does that number come from?

"The guideline is loosely based on an equation that determines milliliter per calorie consumed per day, but even if you’re eating much more or far less daily, it’s a good barometer to think of 2,000 milliliters or 2 liters (about 8 cups) as a middle-ground benchmark," London says.

How much water should you drink based on your weight? Here's how to calculate it:

If you want to determine the exact amount you should drink according to your body weight, you can follow these steps:

1. Take your weight (in pounds) and divide that by 2.2.
2. Multiply that number depending on your age: If you're younger than 30, multiply by 40. If you're between 30-55, multiply by 35. If you're older than 55, multiply by 30.
3. Divide that sum by 28.3.
4. Your total is how many ounces of water you should drink each day. Divide that number by 8 to see your result in cups.

How much water should you drink based on your activity level?

This one's a no-brainer: Anyone who works out on a regular basis should drink more water than someone who's sedentary. Not upping your fluid intake to match your exercise schedule can lead to some unpleasant consequences, too.

"Dehydration can produce a number of different side effects, from feeling a little lethargic to plummeting blood pressure," says London. "While everyone’s sweat rate is different, it’s safe to assume that for every 45 to 60 minutes of exercise you do, you’ll need to drink a minimum of 40 ounces of H2O — a number that will probably seem staggeringly high to some of you."

Even if you don't have symptoms, you can still tell if you're falling short of your water needs. Just check the color of your pee. "It should be a light straw color when you're staying properly hydrated!" London says.

So if you calculated you need at least 72 ounces of water per day based on your weight, that number should jump to 120 ounces (15 cups) or more if you're doing an hour-long workout.

How much water should I drink a day in liters?

To convert your calculation from ounces to liters, follow this simple formula:

Number of Fluid Ounces ÷ 33.8 = Number of Liters

For example, if you're aiming to drink at least 72 ounces or 9 cups of water per day, that's the equivalent of 2.1 liters.

Is drinking a gallon of water a day way too much?

Not necessarily. "It’s possible that you might need a gallon, depending on who you are, how many calories you consume per day, and your level of physical activity," London says. (Pro and endurance athletes: This is you!) However, it's also possible to drink too much water.

"It may induce hyponatremia — severely low blood levels of sodium — which can have severe neurological implications, among other side effects," London explains.

Consult with your physician if you're experiencing excessive thirst (which can indicate blood-sugar abnormalities) or feeling worried you’re drinking too much. Various diseases and medications can impact your hydrations needs. That said, hyponatremia is fairly uncommon, so don't inadvertently dehydrate yourself.

"I’m more concerned that you’re not drinking enough versus overloading, so choose foods high in water content (veggies and fruits!) and drink unsweetened beverages like tea, coffee, and sparkling water regularly," London adds. "Almost everyone I know isn’t drinking enough water and is likely ever-so-slightly sub-clinically dehydrated."

How to drink more water:

Drinking enough water may sound like a challenge, but making a few small changes can help you up your count. Try adopting these tips, as adapted from London's book Dressing on the Side (and Other Diet Myths Debunked):

• Wake up and drink: Start your day with 16 ounces of water — right away. Keep a glass on your nightstand as a visual cue. "I give this tip because it's so easy for anyone and everyone to forget to drink throughout the day depending on where you are or what you're doing. So if you can knock back two cups while you're prepping breakfast or getting ready for the day, you've already taken a step toward your hydration goal before your day has even really started, which can make you feel more energized, too" London says.
• Caffeinated drinks count: Unsweetened beverages such as coffee and tea "count" toward your goal. The USDA Dietary Guidelines recommends getting 300–400 mg per day — about 3–4 cups of coffee, and they're not "dehydrating" contrary to popular belief. "Caffeine may have a mild diuretic effect, but that really just means you're peeing more—not that you're dehydrating yourself," says London.
• Switch it up with sparkling: Seltzer and club soda will help you hydrate, too! Choose flavored or plain options, but skip brands with higher amounts of sodium, acesulfame-K, stevia or sucralose, as they can exacerbate bloating.
• Eat more produce: Produce is packed with water, so add it to snacks and meals. Just one apple, for example, can provide up to 1⁄2 cup of H2O. So snack on extra veggies with salsa, add extra tomatoes to a salad, and get generous with your serving sizes of berries, citrus, melon, grapes and other fruits. "This small but powerful tip can help you feel more satisfied from your meals, provide key vitamins & minerals you need, and contribute to your overall daily fluid needs," says London.
• Jazz up sipping: A splash of juice in your seltzer? Frozen fruit in place of ice cubes? A citrus garnish on your spa water? A super fancy water bottle gifted to you for the holidays?! All these things can help encourage you to drink up. "When it comes to any personal health practice, finding what works for you can be a process," says London. "So if you find something that makes it even slightly more exciting to do something you're already doing and want to do more of...I say, go for it!"
• Bring a bottle everywhere: "So many people are moving from place to place throughout the day— from their homes to their cars to an office space, back in the car to pickup their kids, etc. That's why I'd recommend keeping a bottle either in your bag, or in eyesight in the places that you spend most of your time. This visual cue can help remind you to drink periodically throughout the day," London says.

Drink up, and get ready to feel better than ever with your brand-new, properly hydrated body.

Alyssa is a senior editor for the Hearst Health Newsroom, where she has written research-backed health content for Prevention, Good Housekeeping and Woman's Day since 2017. She has more than 13 years of reporting and editing experience and previously worked as research chief at Reader’s Digest, where she was responsible for the website's health vertical as well as editing health content for the print magazine. She has also written for Chowhound, HealthiNation.com, Huffington Post and more.

Caroline is a writer and editor with almost a decade of experience. From 2015 to 2019, she held various editorial positions at Good Housekeeping, including as health editor, covering nutrition, fitness, wellness, and other lifestyle news. She's a graduate of the Medill School of Journalism and dreams of the day Northwestern will go back to the Rose Bowl.  

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