How to Calculate How Much Water You Should Drink A Day

By Kristen Mccaffrey on
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Learn how much water to drink daily including ideas for staying hydrated, weight loss, a water intake calculator, and more.

Lots of people don't realize the true importance of drinking enough water every day and how it can impact both your health and your weight loss efforts. According to experts in a recent study, drinking just 2 cups of water, which is smaller than the size of a bottled soda, before meals helped dieters lose an extra five pounds yearly and help you maintain your weight loss. Additionally drinking the right amount of water daily can actually speed up your metabolic rate and help to curb overeating when your body confused hunger and thirst. But how much water is enough? Here is how to calculate how much water you should drink a day for both health and weight loss benefits.

  1. Your weight: The first step to knowing how much water to drink every day is to know your weight. The amount of water a person should drink varies on their weight, which makes sense because the more someone weighs the more water they need to drink. A two hundred pound man and 100 pound woman require different amounts of water every day.
  2. Multiply by 2/3: Next you want to multiply your weight by 2/3 (or 67%) to determine how much water to drink daily. For example, if you weighed 175 pounds you would multiply that by 2/3 and learn you should be drinking about 117 ounces of water every day.
  3. Activity Level: Finally you will want to adjust that number based on how often you work out since you are expelling water when you sweat. You should add 12 ounces of water to your daily total for every 30 minutes that you work out. So if you work out for 45 minutes daily, you would add 18 ounces of water to your daily intake.

Daily Water Intake Calculator

Use this hydration calculator to learn how much water you should drink daily based on your weight and activity level.

It is recommend that you drink: Enter your information above and hit "calculate"

To make it a little easier to calculate how much water to drink every day, here are the recommended amounts for a range of weights. Remember to adjust for your activity level.

Weight Ounces of Water Daily
100 pounds 67 ounces
110 pounds 74 ounces
120 pounds 80 ounces
130 pounds 87 ounces
140 pounds 94 ounces
150 pounds 100 ounces
160 pounds 107 ounces
170 pounds 114 ounces
180 pounds 121 ounces
190 pounds 127 ounces
200 pounds 134 ounces
210 pounds 141 ounces
220 pounds 148 ounces
230 pounds 154 ounces
240 pounds 161 ounces
250 pounds 168 ounces

Tips for Reaching Your Daily Water Goals

So now that you know how much water you should be drinking every day, let's talk about how to make sure you actually get enough. Drinking over 100 ounces of water may seem impossible at first, but with these easy tips you can reach your goal in no time.

  • Drink 2 cups (16 oz) of water before every meal: Science has proven that drinking 2 cups of water before every meal helps you to eat less during meal time and lose weight. If you do this three times daily - at breakfast, lunch, and dinner - you have already consumed 48 ounces of water.
  • Morning and Night: Get into the habit of drinking one glass (16 oz) of water when you wake up and another 8 oz glass before you go to sleep every night. This will add another 24 ounces of water to your daily intake. The easiest way to do this is to keep a glass or container of water at your bedside, that way as soon as you wake up and start your day, you can begin drinking water.
  • Keep Track By Your Container: One thing that has proven to help people consumer enough water daily is to buy a special container for their water, like this one or this one, and set a goal of how many times they will fill an finish the container. For example, if you buy a 16 oz container and need to drink 80 ounces of water a day, your goal would be to drink 5 of those daily. Need to drink more water? Try a larger container.
  • Infuse Your Water With Flavor: Water doesn't have to be boring and infusing your water with fruit, herbs, and other flavors can make it much easier to reach your daily goal. Try adding cucumber, strawberries,lemons, limes, and fresh herbs to create flavorful water. This fruit infusion water pitcher is a great way to always have great tasting water on hand.
  • Bubbles: Consider carbonated and sparkling water in addition to regular water. Many people find that adding sparkling water and 0 calorie flavored water makes drinking water throughout the day more fun. Find yourself drinking lots of expensive sparkling water? Consider buying a sodastream and make your own delicious sparkling beverages at home.

What are the benefits of drinking enough water daily?

Water is essential for our bodies to functions correctly and efficiently. It’s vital to our health and can have a huge impact on our overall health and wellness. Most of us know this, but do you actually know why water is so important. Here are the main benefits of staying hydrated:

  • Aids digestion and prevents constipation
  • Carries oxygen and nutrients to you cells
  • Helps stabilize blood pressure and heartbeat
  • Supports healthy joints and joint function
  • Helps regulate body temperature
  • Potentially lowers the risk for disease in the future such as cancer, heart disease, hugh blood pressure, kidney stones, and stroke

How much water should I drink to try and lose weight?

Let’s start out by being clear that drinking water alone will likely not lead to weight loss. However, the benefits of drinking water can help support and encourage weight loss.

First, water helps us to feel full and satiated. When we are hydrated, we tend to eat less since we don’t confuse signs of dehydration with signs of hunger. Many people actually report feeling hungry when they are in fact dehydrated.

Another added benefit of drinking water is that it is less likely that someone will overeat. When your stomach is filled with liquid from drinking water, it is less likely you will eat too much or mindlessly snack throughout the day.

Lastly, if you are focused on drinking more water, you are less likely to reach for sugary drinks and beverages with empty calories. Swapping in water for higher calorie beverages is a great way to lose weight.

More Questions and Answers About How Much Water to Drink

What liquids count towards your daily water goal?

Pretty much all liquids count towards your daily water intake goals. This includes sparkling water, juice, milk, tea, coffee, smoothies, and even soda and diet soda. However, the best and most affordable option is always plain water. And it better for your body than other beverages according to this Harvard study.

A few notes about caffeine. For a long time, people believed that drinking caffeinated beverages like coffee and tea, actually counted against your daily water intake since they are diuretics. However, recent studies suggest that this might not actually be the case.

One other important note, food also contributes to your daily water goals. Some foods, like watermelon, is almost 100% water and therefore counts as well. Since this can be hard to track, just think of food as extra water you are having every day instead of trying to track it.

How much water is too much?

Many people wonder if there is actually a point where you can drink too much water. There are some rare cases of someone over-hydrating, known as hypnoatremia. However, it is very rare and usually only seen in endurance athletes who are over-drinking while doing very intense exercise or in older adults with certain health conditions.

For the average person, this is normally not a concern.

Is drinking a gallon of water bad for you?

Water poisoning or water intoxication is a condition where someone drinks too much water in a short period of time and their cells become imbalanced due to a loss of sodium. It is a serious condition but extremely rare.

General guidelines suggest that you shouldn't drink more than 27-33 ounces of water per hour. This means drinking a gallon of water in an hour wouldn’t be recommended.

Any type of water challenge could potentially be dangerous and it is always best to listen to your body.

How much water do you really need?

At the most basic level, you should be drinking enough water every day that you do not show any symptoms of dehydration and that your body is functioning well. There is no exact number for everyone since it varies based on your body, activity level, diet, climate, and more.

Generally speaking, doctors recommend that you get at least 6 cups of water daily at a minimum but most people should be drinking more than that. One easy indicator is urine. Your urine should be fairly frequent and like yellow or clear in color. Darker or smelly urine is an indicator of dehydration and usually indicated you should be drinking more water.

Does water affect your energy levels?

Water can have a huge impact on energy levels. People who are dehydrated report feeling more tired, sluggish, and lethargic. Staying hydrated helps keep your cells functioning properly and helps energy levels stay high. In fact, it is one of the most recommended tips for boosting energy levels quickly.

Does water intake affect brain function?

Water and proper hydration have been shown to greatly benefit brain function. Specifically, staying hydrated can boost mood and mood stability, improve concentration, improve cognition, aid memory, prevent headaches, and even reduce stress.

How can I tell if you are dehydrated?

Here are some of the most common symptoms of dehydration:

  • Feeling thirsty
  • Dry mouth
  • Headache
  • Dizziness
  • Change in mood
  • Feeling tired or weak
  • Trouble concentrating or focusing
  • Increase in body temperature
  • Rapid breathing and/or heartbeat
  • Flushed or red skin
  • Dry mouth, eyes, or lips
  • Dark yellow or smelly urine (note, this isn’t solely caused by dehydration and is common after taking multivitamins or eating certain foods as well. This evens out throughout the day, so most of your urine should mostly be light or clear.)

Should I drink 8 glasses of water daily? What about the “8 by 8” rule?

To help people have a tangible amount of water to focus on, there was a push to recommend that the average person drink 8 glasses of water by 8 PM daily. This would mean that you drank at least 64 ounces of water daily.

There is no solid evidence suggesting that this is, in fact, the right amount, but it is probably a good recommendation for a minimum amount. Depending on your lifestyle, body type, diet, age, and more - this will vary.

What factors affect how much water you need daily?

The amount of water someone needs daily depends on a number of different factors. Here are the most common factors that affect water needs.

  • Activity Level and exercise: People who exercise or do rigorous activity will need to consume more water daily. However, the exact amount varies depending on the activity, muscle mass, and climate.
  • Climate and temperature: If you live in a hot and humid climate, or it’s a hot day, you will need more water. As we sweat and perspire, we need to replace the water we are losing.
  • Diet: Diets that are higher in sodium may require more water to flush out that sodium.
  • Pregnancy and breastfeeding: Pregnant and nursing moms will need more water than the average person.

How do you know if you are well hydrated?

The easiest way to know that you are well hydrated is to pay attention to your urine. Generally speaking, it should be light yellow or clear without too much of a smell. Thirst is another indicator, but many people confuse this with hunger.

What about caffeine? How does it affect water intake and hydration?

There used to be a common belief that caffeine counted against hydration since it is a diuretic. However, recent studies have shown it may not affect hydration as much as was previously thought. With that said, water is always the best option when trying to stay hydrated.

How much water do you need during exercise?

It is recommended that you drink water before, during, and after exercise. For most exercise, plain water will do. Some people recommend drinking an electrolyte drink after doing any vigorous exercise for an hour or more to replace lost electrolytes.

One other note, drinking too much water too fast during exercise can cause cramps and stomach pain. It is best to sip slowly while working out in most cases.

What other questions do you have about how much water to drink?

Water intake calculator with a glass of water.
18 Comments
On How to Calculate How Much Water You Should Drink A Day
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John
May 23, 2019 - 16:28
To get all the water I need, I like to use what I term as the "Wiz and Water" method.

Drink a full glass of water (12-16 oz) when you wake up in the morning. Then after you pee (wiz), drink another glass of water. Repeat throughout the day. It's a no brainer way to get enough water and you won't drink too much or too little.
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Doris
February 23, 2019 - 15:15
This is confusing here you go by weight period . A doctor once told you Mother even though she drank the amount for her age it was to much for for her activity or inactivity . Which made sense as a activity working woman would use that water
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Jenny Exner
January 28, 2019 - 13:57
That is nowhere near enough water for a person who works in a hot and dry environment. Nevermind taking into consideration: height (along with weight), sodium intake, smoker/non-smoker, diet (foods high/low in water), alcohol consumption, activity levels, medications and/or vitamins and supplements that might require more or less water intake. There's SO much to consider - this calculator is a great suggestion, but nowhere near accurate for every gender and size of human.
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Courtney
December 27, 2018 - 18:11
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Love the site
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Sheerah
September 15, 2018 - 20:30
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I am a vegetarian soo I hope you have recipes that cater for people like me and I have a million food allergies. My goal is too reach my acquired BMI.
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Alex
July 22, 2018 - 02:46
You are dizzy because you are way under your water need - yes you will loose salt through sweat.. but you also loose water through sweat - the more you sweat the more you need water. 40oz for 160lbs is WAY to little.
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J
July 13, 2018 - 19:05
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I drink 40oz of water a day (its marked on my bottle) and I weigh 160lbs. I work in a hot and dry environment. And 40oz of water is TOO MUCH WATER. I lose so much salt and vitamins I get dizzy and black out. And I wake up in the night with a full bladder. You should just about drink a cup of water with each meal. its not rocket science. If you're working extra hard drink electrolyte drinks on top of that.
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Annie
July 2, 2018 - 10:57
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If you're drinking enough water for your body AT A HEALTHY WEIGHT, you're drinking enough water. Increasing intake beyond what the kidneys can process (approximately 3.5L/hour) is harmful and potentially deadly. The way to calculate the amount of water to drink is to find a healthy weight for your height & multiply it by .5. Of course, your intake might go up with added exercise or in hot weather but intakes above twice that can deplete vital nutrients and more than that can cause hyponatremia, which is extremely dangerous.
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David Jones
May 31, 2018 - 12:57
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I am 300 pounds so does that mean I should drink 150 ounces of water a day and if so what time should I get up and how much should I drink an hour.
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Janet
May 25, 2018 - 10:01
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Great info , include info on diet websites and diabetics website. Most people don't know the amount of,water the actually need which can change there health along with eating more vegetables and way less carbs. Thanks...
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Omatiklan
May 7, 2018 - 12:19
First, I think your chart is a great starting point for healthy hydration. But I'm wondering, what's your source for this chart and calculation? Most clinicians, researchers and even U.S. agencies (i.e., FDA, CDC, USDA, OSHA, etc) all distance themselves from a quantity-specific recommendation since hydration needs are wildly variable from person to person and from one environment to another.

As I mentioned, your chart is a good starting point but people should really take into consideration their health, overall fitness, daily activity levels, and environment (for example, exposure to high temperatures) in assessing their individual hydration needs. Relying on a static formula with one or two variables (like weight or age) could leave many people short of healthy hydration.
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Ilsy Bu
June 15, 2016 - 11:54
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so what happens if you drink double the amount of water daily? Will this have an effect on the amount you can lose or no? great article. Thank you!
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EdeLyn Tabigue
June 13, 2016 - 22:57
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"Its help me a lot"thank you Godbless!
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Ashley Walton
February 27, 2016 - 03:43
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Very helpful! I will share a link in my health and fitness blog!
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Willamena King
February 26, 2016 - 23:04
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It works well.
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mike cavazos
January 13, 2016 - 14:40
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very informative article!
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Malisha Goggans
October 9, 2015 - 08:35
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Great info...
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January 13, 2016 - 12:32
lmao! I was thinking the SAME THING Jessica!!