How to calculate how much water you should drink (2024)

Byline: Jennifer Stone, PT, DPT, OCS, Clinic Supervisor

Summer is right around the corner … and with it, summer activities, warmer temperatures and an increased risk for dehydration. Here are some tips to help you make sure you are drinking enough fluids to maintain good levels of hydration.

You are probably all aware of the “cardinal rule” that says adults should drink six to eight 8-ounce glasses of water per day. The truth is, this is an estimate and the actual amount you should be drinking per day can vary quite significantly. There are multiple factors that can impact how much water you should be drinking.

Your weight is one variable that changes the amount of water you should be drinking. To help you establish a baseline, you can use the following rule-of-thumb equationdescribed inU.S. News & World Report.

How to calculate how much water you should drink (1)

In short, the equation tells you to take half your body weight, and drink that amount in ounces of water. In the example, notice that you should be drinking more than 12 glasses of water, not eight!

Your exercise habits affect the amount of water you should be drinking, as well.The American College of Sports Medicine recommendsadding 12 ounces of water to your daily intake for every 30 minutes that you plan to work out.

How to calculate how much water you should drink (2)
If you are exercising outside and it is very hot, you may need to add more.

There are several special considerations to maintaining a healthy hydration level. If you are pregnant or breastfeeding, you need to increase your fluid intake by 24 to 32 ounces depending on how much you weigh, according to the American Pregnancy Association. It is also important that you get a lot of your hydration from water. If you are primarily drinking sodas or caffeinated beverages such as coffee or tea, you do not get as much “bang for your buck” when it comes to fluid intake (i.e., they don’t “count” as much).

The good news is there are some fairly easy rules of thumb to follow when it comes to hydration. One of the important ones is to pre-hydrate. In other words, drink BEFORE you start feeling thirsty, or BEFORE you do an activity. Going running? Drink several glasses of water before you start. Thirst is actually a sign of dehydration, so if you feel thirsty, you have some catching up to do!

Also, monitor your urine. If you are adequately hydrated, you should be urinating about once every two to four hours, and your urine should be colorless or a very pale yellow (the color of hay or lighter). If it is darker than that, you haven’t had enough fluid. Headaches and dizziness are a late sign of dehydration. If you start experiencing those, you really need to up the water intake, and quickly.

Dehydration can turn a fun summer activity into an unpleasant experience at best, or a trip to the emergency room at worst.

Don’t wait until it’s too late. Bring water bottles with you, and keep yourself and your family hydrated during your summer fun!

More info:

Sources cited:

About the author: Jennifer is a Clinic Supervisor for Mizzou Therapy Services (Rangeline location) and a board-certified specialist in orthopedic physical therapy. She is also CAP certified in women’s health physical therapy. She has five years of experience in physical therapy and earned her Master’s degree from Texas State University, her doctorate from Massachusetts General Hospital Institute for Health Professions, and completed an orthopedic residency through Evidence in Motion.

How to calculate how much water you should drink (2024)

FAQs

How to calculate how much water you should drink? ›

Your recommended daily water intake is related to your body size and activity level. In essence, not everyone needs eight, eight-ounce glasses of water each day. Some people may need less, while others need far more. The general rule is to drink one ounce of water for every two pounds of body weight

body weight
Strictly speaking, body weight is the measurement of weight without items located on the person. Practically though, body weight may be measured with clothes on, but without shoes or heavy accessories such as mobile phones and wallets, and using manual or digital weighing scales.
https://en.wikipedia.org › wiki › Human_body_weight
.

How do you calculate how much water you should drink? ›

Multiply by 2/3: Next you want to multiple your weight by 2/3 (or 67%) to determine how much water to drink daily. For example, if you weighed 175 pounds you would multiple that by 2/3 and learn you should be drinking about 117 ounces of water every day.

What is the correct formula to calculate a person's daily need of water? ›

The best way to determine your daily water requirements is to start with your weight and multiply by 2/3 (0.67). For a 190-pound person, that would look like 190 x 2/3 = 127 ounces of water daily. The next step is to account for your activity level.

How do you calculate water? ›

The best way to calculate your water intake is use your current body weight to do the math. People must drink approximately two-thirds of their weight in pounds, converted into ounces. For example, a 150-pound adult conversion example is listed below. 150 x ⅔ equals 99 ounces.

What amount of water should I drink daily? ›

General recommendations
AgeDaily Adequate Intake
men, 19 and older13 cups, or 104 ounces
women, 19 and older9 cups, or 72 ounces
pregnant women10 cups, or 80 ounces
breastfeeding women13 cups, or 104 ounces
4 more rows

What is the formula for water requirement? ›

How can I easily calculate my minimum daily water requirement? Begin by noting your weight in pounds. Then, multiply your weight by 0.67 (⅔) to establish your minimum daily water requirement.

How much water should you drink based on your weight? ›

A person's size, weight, activity level, and area of living can influence their water requirement. You should drink half an ounce to an ounce of water per day for each pound you weigh. For example, if you weigh 150 pounds, you should drink 75 to 150 ounces of water a day.

How much water should I drink according to a day chart? ›

“Aim to drink half an ounce for every pound of body weight,” she says. “In other words, divide what you weigh in half and aim to consume that many overall ounces of water daily from a variety of sources.” For example, if you weigh 150 pounds, aim to drink 75 ounces of water a day, which is around nine cups per day.

How do you calculate free water intake? ›

Free Water Calculation
  1. Formula A is 70% free water.
  2. Total volume of formula prescribed is 1300 mL.
  3. Estimated patient fluid needs = 1600 mL per day.
  4. 1300 mL x 0.70 = 910 mL free water available to meet patient fluid needs.
  5. 1600 mL – 910 mL = 690 mL additional free water needed to meet 100% estimated fluid needs.

What is the formula for calculating a hydrate? ›

Formula of a Hydrate (Anhydrous Solid⋅xH2O)

In order to determine the formula of the hydrate, [Anhydrous Solid⋅xH2O], the number of moles of water per mole of anhydrous solid (x) will be calculated by dividing the number of moles of water by the number of moles of the anhydrous solid (Equation 2.12. 6).

What is a water calculator? ›

One definition of a water calculator is a tool that provides rapid, easy, and efficient water specification by storing general information on water use for a wide range of items. The widespread availability of water calculators attests to the widespread concern for water conservation that inspired their creation.

How to drink water correctly? ›

Drink your first glass of water after you wake up to hydrate your body after a long night's rest. Take your breakfast at least half an hour after the first glass. ​It's approximately 1 hour after your breakfast; have a glass of water and start your work day. ​Have a glass of water 30 minutes before lunch.

How many ounces of water to drink a day? ›

Here are some tips to help you make sure you are drinking enough fluids to maintain good levels of hydration. You are probably all aware of the “cardinal rule” that says adults should drink six to eight 8-ounce glasses of water per day.

How do you calculate how much water I should be drinking? ›

Weight-based Water Intake

Some people may need less, while others need far more. The general rule is to drink one ounce of water for every two pounds of body weight. All you have to do is weigh yourself, then divide the number of pounds by two to figure out your needed water intake. Or check out the chart below.

How much water should I drink at my age? ›

How much fluid to drink each day
Infants 0–6 months*0.7 litres
Men 19 years+2.6 litres (about 10 cups)
Women 19 years+2.1 litres (about 8 cups)
Pregnant girls 14–18 years1.8 litres (about 7 cups)
Pregnant women 19 years+2.3 litres (about 9 cups)
9 more rows

What is the healthiest water to drink? ›

Mineral water and alkaline water may be some of the healthiest types of water because they provide your body with essential nutrients, but simply drinking safe, uncontaminated water should be your number one priority.

Is 64 ounces of water a day enough? ›

Adults. The current IOM recommendation for people ages 19 and older is around 131 ounces for men and 95 ounces for women. This refers to your overall fluid intake per day, including anything you eat or drink that contains water, like fruits or vegetables.

How much water should I drink per standard drink? ›

Use the 1-for-1 Rule

night ahead of you, drink one glass of water for every alcoholic drink you sip on. This should help you not only mentally manage how much your drinking at any given moment but should dilute the amount of alcohol that enters your system as it happens.

Is a gallon of water a day too much? ›

According to the U.S. National Academies of Sciences, Engineering, and Medicine, an adequate daily water intake is about 3.7 liters for men (roughly a gallon) and about 2.7 liters for women (about seven-tenths of a gallon). Another general rule of thumb is to drink “half your body weight in ounces” for a regular day.

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