With many health sites publishing recommendations for water intake per day, usually measured in cups, consumers are often confused about how to determine if they’re getting enough water.

The fact that water bottles also have different sizes, and many don’t publish a Nutrition Facts label, can make it challenging to ensure proper hydration.

So how many cups of water are in a water bottle? Does it depend on the brand? And how many cups of water should you drink for optimal health?

In this article we’ll answer these questions and more, by breaking down the number of cups in some of the most popular water bottle brands, and sharing our thoughts on whether there's an optimal number of cups of water to drink daily for good health.

How Many Cups in Popular Brands

Most bottled water is measured in ounces (oz), and 1 oz = 0.125 cups.

Here's a breakdown of the number of cups of water in some of the most popular bottled water brands:

Standard glass of water (8 oz) - 1 cup

Fiji (regular size) - 2.1 cups

LIFEWTR - 2.1 cups

Essentia - 2.5 cups

Core - 3.8 cups

Flow - 4.2 cups

Certain brands like Poland Spring, SmartWater and Evian sell so many variations of water bottles that we can’t provide a general answer.

With the formula above, it's possible to calculate the number of cups in any water bottle. Just multiply the number of ounces in that water brand by 0.125 to get the number of cups.

Is Eight Cups a Day Necessary?

One of the main reasons that people analyze how many cups of water are in water bottles is because there's a popular health theory that eight cups of water per day can improve health.

But is this really true? A TEDTalk with over 500,000 views features a doctor analyzing this trend to determine if it's legit:

Our Clean Water Picks

Brita Water Filter is our top countertop water filter pick, because it's been shown in studies conducted by ConsumerLab (an independent research firm) to significantly reduce heavy metal levels and entirely eliminate microplastics.

UVBrite is our top water bottle pick, because it's made of stainless steel which means it's free of potential microplastic leaching (an issue with plastic bottles).

This bottle can even filter water using ultraviolet (UV) wavelengths of light which are clinically shown to be effective for removing harmful contaminants like bacteria.

Aquasana Whole House Water Filter is our top whole-home filtration solution.

Whole-home filters reduce contaminants in all taps and all showers throughout the house, and are the most thorough way to ensure the purity of drinking and bathing water.

Conclusion

The number of cups in a water bottle depends significantly on the water bottle brand.

It's possible to calculate the number of cups in any water bottle with a simple formula: multiply the number of ounces by 0.125.

There doesn't seem to be much scientific evidence suggesting that eight cups of water per day optimizes health.

The number of cups of water someone needs to stay optimally hydrated will vary significantly from person-to-person based on things like weight, sex, exercise and genetics.

We believe the best way to stay hydrated, from both a cost and health perspective, is to purchase a reusable plastic-free water bottle. Keeping it with you on-the-go helps you remember to be regularly drinking (ideally filtered) water.