Water Intake by Weight Chart

Water intake chart by body weight

Here is the daily drinks target for eight common body weights, from 100 lb to 250 lb, with the low-to-high range around each one.

The "drinks" part matters. These numbers count what you drink (water, tea, coffee, milk, and so on), not the water that comes along with food. Food typically supplies around 20% of a person's total water, so total water for the day is higher than the numbers in the chart. The "range" column is the 30 to 35 mL/kg spread, so use it as a window rather than a bullseye. The cups column uses 8 fl oz cups.

If your weight sits between rows, you can read between them. Our Daily Water Intake Calculator does that for any weight and adds exercise and heat, if you would rather not interpolate by hand.

How the numbers are built

The site's formula is simple:

1. Take your body weight in kilograms.
2. Multiply by 32.5 mL, the middle of the 30 to 35 mL/kg rule of thumb.
3. Add 0.6 L for each hour of exercise.
4. Round to the nearest 50 mL.

Hot weather uses the top of both ranges, and the chart rows are the "no exercise, typical weather" case. The full method, with worked examples, is on the water intake formulas page. The formula is for adults only.

Two things are worth being plain about. First, the 30 to 35 mL/kg figure is a rule of thumb, not a law. We did find it stated on a nutrition education page on OncoLink, credited to a nutritional counseling program, which tells readers to multiply their weight in kilograms by 30 to 35 mL and notes the figure is most accurate for adults over 30. That's a single patient-education page, not a formal guideline or a review, so we treat it as evidence that the convention is in circulation and nothing more. We didn't find a formal guideline we could read for it.

Second, we checked the model against the one authoritative benchmark we could read. The National Academies set total water at about 2.7 L (91 oz) a day for women and 3.7 L (125 oz) for men, with about 80% of it coming from drinks and the rest from food. They publish the drink portion as 2.2 L for women and 3.0 L for men. The site's formula lands within about 50 mL of those two numbers at 147 lb and 201 lb. Those aren't average weights, since CDC data put the average adult at about 172 lb for women and 199 lb for men. That match is a sanity check, not proof, because the National Academies figures aren't scaled to body weight. Mayo Clinic describes the same ballpark, about 11.5 cups (2.7 L) to 15.5 cups (3.7 L) of total fluid for the average healthy adult, and also puts food at about 20%.

What the chart says for common weights

Most "per weight" questions are really three or four specific cases, so they're answered one by one below.

How much water should a 200 lb man drink?

About 2,950 mL a day from drinks (roughly 100 fl oz, 2.95 L or 12.5 cups), with a range of 2,700 to 3,200 mL. That's close to the National Academies' 3.0 L of drinks for men, which is about 80% of their 3.7 L total. The formula uses weight, not sex, so a 200 lb woman gets the same number.

How much water should a 150 lb woman drink?

A 150 lb adult falls halfway between the 140 lb row (2,050 mL) and the 160 lb row (2,350 mL), so roughly 2.2 L of drinks a day on a quiet, mild day. Again, the formula doesn't change for sex. Pregnancy and breastfeeding are the exceptions to leave the chart for, and that's covered below.

How much water should a 225 lb man drink?

A 225 lb adult sits just above the 220 lb row (3,250 mL) and well short of the 250 lb row (3,700 mL), which puts the target at around 3.3 L a day from drinks.

What about everyone else?

Read the closest row, or use the Daily Water Intake Calculator for an exact figure. If you're heavier or lighter than the chart covers, the same 30 to 35 mL/kg logic applies, but the further you get from the middle, the more it makes sense to lean on thirst and the other checks below.

The "half your body weight in ounces" rule

You have probably seen this one: drink half your body weight in ounces. A 200 lb person would aim for 100 oz. It's a shortcut with no study behind it, but it lands close to the 32.5 mL/kg figure used here. Half an ounce per pound works out to about 32.6 mL per kilogram, which is nearly the same as the 32.5 mL/kg baseline used here. In the chart, the 200 lb row shows 100 fl oz, the same answer both ways.

So the two rules agree. The difference is that the ounce rule gives you a single number and says nothing about heat, exercise, or the fact that the answer is a range. Treat it as a good shortcut for a normal day and not a target to hit to the ounce.

Why exercise and heat add more

The chart is the "no exercise, typical weather" case. The National Academies note that people who are very physically active or who live in hot climates may need more water than the reference levels, and Mayo Clinic lists exercise, hot or humid weather and high altitude among the things that raise your needs. Illness with fever, vomiting or diarrhea is on that list too.

The site handles exercise by adding 0.6 L per hour of activity. The real number varies a lot from person to person. The American College of Sports Medicine position stand says sweating rates differ considerably between individuals and recommends customized fluid plans, and it suggests estimating your own sweat rate by weighing yourself before and after a workout. So the 0.6 L figure is a starting point. If you train hard, run hot, or sweat heavily, weighing yourself is the better method. In hot weather the site uses the top of both ranges, which means the 35 mL/kg end of the baseline plus the higher end of the exercise allowance.

Thirst and urine color still matter most

A chart gives you a sensible starting number. Your body gives you the feedback. Mayo Clinic says you're probably drinking enough if you rarely feel thirsty and your urine is colorless or light yellow. Headaches, dark urine and lower physical performance can be signs you're falling short. It also suggests drinking with meals, between meals, around exercise, and when you feel thirsty.

For a healthy adult, that makes the practical routine easy: use the chart for a rough daily target, then adjust by how you feel and what you see. If the chart says 12 cups and you're rarely thirsty with pale urine at 9, use that as your cue.

Who should not use a chart like this

This page and the formula are written for healthy adults. A weight chart isn't the right tool if any of these apply:

• You're pregnant or breastfeeding. Mayo Clinic notes these can increase fluid needs, and the amount is worth discussing with your own clinician.
• You have a kidney, heart or liver condition. These conditions can change how much fluid is right for you.
• You have been told to limit fluids, or you have been given a specific fluid target.
• You're buying for or caring for a child. The formula and chart are for adults only.

If one of those fits, the number that matters is the one from the person treating you. This page is general information, not medical advice.

Keep reading

• Water Intake Formulas ComparedHow the half-weight rule, the 2/3 rule and mL per kg differ.
• Sweat Rate CalculatorFind your sweat rate from a weigh-in before and after a workout.
• Pregnancy Water Intake CalculatorThe National Academies figures for pregnancy and breastfeeding.
• How Much Water Is Too Much?How overhydration happens and who is at risk.

Sources

1. National Academies of Sciences, Engineering, and Medicine. News release, Feb. 11, 2004: Report sets dietary intake levels for water, salt, and potassium to maintain health and reduce chronic disease risk.
2. Mayo Clinic. Water: How much should you drink every day?
3. Sawka MN, Burke LM, Eichner ER, Maughan RJ, Montain SJ, Stachenfeld NS. American College of Sports Medicine position stand. Exercise and fluid replacement. Medicine & Science in Sports & Exercise, 2007;39(2):377-390. PubMed 17277604.
4. OncoLink. Determining Fluid Requirements. Credited to the Tracey Birnhak Nutritional Counseling Program. Cited only as an example of the 30 to 35 mL/kg convention in print.
5. National Academies Press. Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate, 2005. Water chapter: https://www.nationalacademies.org/read/10925/chapter/6
6. Centers for Disease Control and Prevention, National Center for Health Statistics, "Body Measurements" (mean weight of adults 20 and over, August 2021 to August 2023): https://www.cdc.gov/nchs/fastats/body-measurements.htm

General information for healthy adults, not medical advice. If you are pregnant or breastfeeding, or you have kidney, heart or liver conditions or a fluid limit, ask a clinician first. Terms and medical disclaimer.