Here’s How Much Water You Should Drink Every Day, According to Dr. Andrew Huberman

Water is our body’s most essential nutrient, and we’re pretty good at drinking it so that we don’t, you know, die.

But, the average person (myself included) sucks when it comes to knowing how to hydrate effectively for health, cellular function, and performance.

The problem isn’t lack of quality data. It’s information overload. Everyone’s eager to share their opinion on how much water you should be drinking, which has diluted the internet with a whole slew of confusing, conflicting information.

Dr. Andrew Huberman, host and creator of The Huberman Lab podcast, solved this with one of his more recent episodes: How to Optimize Your Water Quality & Intake for Health. The entire podcast is a treasure trove of awesome information and worth the listen. But, to make things easy, I’ve extracted and condensed the “how much water to drink” segment so that you can digest it and quickly put it to use.

I’ve also got a neat little surprise at the end that I think you’ll find useful.

Note that this is a highly-condensed version of Huberman’s very detailed conversation on how much water to drink. If you want the science, studies and all the dirty details, listen to the episode and check out the links on his site. He explains it better than I ever could.

Why Is Knowing How Much Water to Drink So Important?

I’m an average guy. I don’t need a deep understanding of organic chemistry or how drinking water affects me at the molecular level. These three things, however, are nuggets of information that I think are worth highlighting:

💦 Slight dehydration (even just 2%) negatively impacts brain and body function

This includes everything from strength, endurance, memory, and focus, to creative thinking. It’s also been known to induce brain fog. There are MANY studies that confirm this. Hydrating properly staves off these effects while increasing physical vigor and output.

💦 You may be dehydrated even if you think you’re not

As it turns out, methods for “self-measuring” dehydration aren’t very reliable, despite what your health-conscious friends and family might have to say. (Yes, this includes the skin pinching method.)

Dehydration isn’t actually measured in a traditional sense. There's not a value for dehydration for something like a piece of your body’s tissue. It’s “measured” based on how much less water you drink than what science says your body needs.

For example, if you drink 2% less water than recommended, you can assume that you are roughly 2% dehydrated.

Fortunately, as we’ll get into further below, science offers sound guidelines on how much water we need to drink to stay sufficiently hydrated.

💦 The first 10 hours after waking are the most important because your kidneys function based on a circadian rhythm

Sleep isn’t the only thing regulated by your body’s internal “clock”.

As we’ve come to find out, your kidneys are too. They are very efficient and active during the first 10 waking hours of your day. Afterward, their performance is greatly reduced as you wind down in the evening and prepare for sleep.

This is a good thing, otherwise you’d be running to the bathroom a lot more than you already do. Knowing this fact about kidney function helps to direct our knowledge on how much water to drink and, perhaps just as importantly, when.

Here’s How Much Water You Should Be Drinking

Huberman does a wonderful job of navigating through the bullshit to give you sound, concise guidance on how much water you need to drink.

Keep in mind that these are recommendations based on the scientific literature and not to be taken as strict advice from a medical doctor. Huberman is not that and I’m definitely not either. 

The values he provides on his podcast, which I’ve summarized below, are conservative estimates so that you overshoot, rather than undershoot, hydration. 

🚶 For sufficient BASELINE hydration (i.e. normal day-to-day, not exercising, not crazy hot/sweaty) for the FIRST 10 HOURS, you should drink:

On average, 8 oz of fluid every hour.

That’s 80 oz total over the first 10 hours (or 2360 mL for the rest of the non-US world).

Keep in mind this is an average, and it’s perfectly fine to drink varying amounts at various times throughout the morning. Sipping or chugging is fine. Just try to keep a somewhat steady intake and don’t drink everything in the last 2 hours.

Also note that:

• This doesn’t have to be straight water, other beverages count toward your fluid intake
• Caffeinated beverages and other diuretics do NOT count

🏃 For sufficient hydration while EXERCISING during those FIRST 10 HOURS, you replace your baseline value with one derived from the “Galpin” equation:

The Galpin equation is your body weight in pounds divided by 30, which equals the number of ounces you should consume, on average, every 15-20 minutes.

For example, I weigh 170 pounds, so 170/30 = 5.67 oz every 15-20 minutes. Just to be safe I’d round up and estimate drinking 6 oz every 15-20 minutes. If I’m working out for an entire hour, that means I should drink 18-24 oz every hour.

Note that:

• Sipping fairly consistently throughout your workout is best for optimization, but it’s not a huge deal if you’re a gulper instead. Again, just don’t wait until the very end and chug everything.
• For you metric folks, the equation is 2 mL of water per kg of body weight every 15-20 min, on average.
• If you sweat a lot or are in heat, a good rule of thumb is to increase the Galpin equation values by 50-100%.

If you’re a sauna person:

Huberman recommends at least 8 oz (16 oz is better) for every 20-30 min you’re in there. 

If you’re a coffee or crazy tea drinker:

When consuming caffeine or other diuretics, it’s highly recommended to increase your non-caffeine fluid intake 2:1.

So, if drinking 6-8 oz of coffee, drink 12-16 oz of water to offset. It wasn’t super clear to me whether that was in addition to your baseline hydration or in total, but that was the guidance given.

🌙 During the evening hours, after the first 10:

It’s recommended to reduce your fluid intake drastically and consume no more than 5 (maybe 8 oz) total before sleep. Again, that’s total. Not each hour.

Also, it’s been shown that how often you have to pee at night is somewhat dependent on the rate at which you drink. That means sipping instead of gulping during your evening hours should help reduce the number of times you get up to pee in the middle of the night.

A few last things to note:

Thirst is a reasonable guide to use when dehydrated.

Thirst, however, doesn’t always keep up with your body’s level of dehydration. That means by the time you are feeling parched, you’ve likely already been in a state of dehydration for some time.

As an extremely basic rule of thumb – if parched, consume fluids (without caffeine or other diuretics).

And if for some reason you’re following the guidelines to a T and still feeling parched, something might be off that you may want to investigate. But again, if you’re thirsty, just drink more.

And that’s it!

There are a few things throughout the podcast that aren’t entirely clear to me, such as how much water to drink if you exercise in the evening outside of that first 10-hour window, but Huberman definitely provides a good starting place for calculating how much water you need to drink.

I Took Things A Step Further

Here’s that little surprise I was talking about in the beginning.

It’s weird, but being an engineer, I love spreadsheets. I spent some time creating a (mostly) simple calculator that you can use to spit out a printable version of how much water you should drink each day.

This spreadsheet takes Huberman’s guidelines, combined with a few of my own assumptions, to create a crystal clear picture of your recommended water intake. (Since I know running the calcs yourself is kind of a chore.)

Here's what it looks like:

And here’s the printable output:

Note that I used Huberman’s most conservative values when creating this calculator. The extra assumptions that I made are ALSO conservative in nature. That means the outputs of this spreadsheet are doubly conservative and should only be treated as a pretty darn good, non-medical recommendation of how much water to drink.

Here’s the link to the file on Google Drive:

How much water to drink [calculator]_Public.xlsx

It’s locked for obvious reasons, so you’ll have to download/save a copy to your computer before you can edit and follow the directions.

Again, I’m not a doctor, so use it at your own discretion. I originally made it as a tool for myself and family/friends, then decided it would be useful for the masses.

Many thanks to Dr. Andrew Huberman for his awesome podcast and specifically his episode on water. If there’s anything I goofed during the translation into this article and the spreadsheet, I apologize and will correct whatever is needed.

Best,

Jason