How Many Ounces in a Gallon - Ounce to Gallon Conversions

Along with benefits such as living a more sustainable lifestyle and everyday convenience, having a range of different water bottle sizes can be very helpful in helping you track your daily water intake and meeting your hydration goals.

This easy-to-use U.S. to metric conversion guide will make it even easier to track your hydration on the go — plus provide other useful tips.

In this practical guide, you'll find the answers to all your questions about U.S. to metric conversions and much more, including:

  • How many ounces in a gallon
  • How many ounces in a half gallon
  • How many water bottles in a gallon
  • How many ounces of water to drink in a day

How Many Ounces of Water Should I Drink a Day?

If you're wondering how many ounces of water to drink in a day, it depends on several factors, including the intensity of your activities, climate, health conditions, and gender. For example, intense high-impact exercise such as running will cause you to sweat more, which is why experts from the Mayo Clinic recommend drinking extra water to make up for fluid loss.

Factors to consider when planning for your optimal hydration include:

  • Health Conditions
Various illnesses can have symptoms which contribute to fluid loss, such as fever and sweating, diarrhea, and vomiting. In those cases, more water than the recommended daily allowance is needed to replace the loss of hydration.
  • Pregnant and Breastfeeding Women
Pregnant or breastfeeding women also need extra fluids. Based on recommendations from the Office on Women's Health, pregnant women need to drink about 2.4 liters or 81 ounces of fluids daily, which equals 0.6 gallons. Breastfeeding mothers should drink approximately 3.1 liters or 108 ounces of liquids per day, the equivalent of 0.8 gallons. It’s always best to get your doctor’s input on your health during or after pregnancy.
  • Climate
Another factor to consider when calculating how much water you need to drink is the climate you live in. In hot climates with lots of sun exposure, your body can dry out quickly and make you feel thirsty, a red flag for mild dehydration. In contrast, cold, high altitude climates might not cause you to feel thirsty, but dehydration can still take hold. Dry air from the high altitude, along with additional loss of carbs due to more frigid temperatures, can cause a significant amount of fluid loss.

General Guidelines

While these different scenarios should always be considered, as a general guideline, The National Academies of Sciences, Engineering, and Medicine advises the following water intake guidelines. We’ve provided water amounts in cups and liters, plus the oz to liter conversion.

  • Daily Hydration for Men: 15.5 cups; 3.7 liters; 126 oz
  • Daily Hydration for Women: 11.5 cups; 2.7 liters; 91 oz

How Many Ounces in a Gallon?

What about by the gallon? Some people like to keep their hydration goals front and center, and use a big bottle to help track how much water they drink. For when ounces or cups just won’t cut it, measure water by the gallon.

Here’s the math. There are 128 oz in a gallon, which conveniently is pretty close to recommended daily fluid intake for men and women:

  • Men: about 1 gallon of water per day
  • Women: 0.7 gallons per day

At Iron Flask, our new product line of one-gallon water bottles makes it easy and convenient to stay adequately hydrated throughout the day. Dehydration is no fun, and comes with symptoms like fatigue, headaches, and muscle cramps that we’d all rather avoid.

Moderation is key. Too much hydration can also be dangerous. Although drinking too much water is rare for healthy adults, athletes can occasionally over-hydrate, a condition known as hyponatremia. This happens when the sodium content in the blood becomes too diluted, which can be serious and life-threatening.

The key is balanced hydration. Staying adequately hydrated will ensure top athletic performance or simply allow you to enjoy your activities to the fullest. According to the Mayo Clinic, a healthy balance of water in the body is essential for a long list of bodily functions such as temperature regulation, lubrication of joints, protection of sensitive tissues, and waste removal.

Half Gallon to Oz Conversions

If a gallon feels a bit too big, go for a half gallon. Knowing how many ounces in a half gallon makes it easy to track your daily water intake against your goal. The 64 oz to gallon conversion equals a half gallon. So adult males simply have to drink two refills of the Iron flask water bottles in the 64 oz size to meet the daily guidelines. For adult women, the amount would be around 89 ounces of liquid per day, which would equal about one full 64 oz water bottle, plus half a refill.

An even easier calculation is the 128 oz to gallon conversion, which equals one gallon. At Iron Flask, we feature the one-gallon water bottle size, the exact recommended amount of daily hydration for adult males. Women need to drink slightly more than half of the one-gallon Iron Flask bottle (0.7 liters) to meet their water intake guidelines.

The 64-oz and one-gallon water bottle sizes are great for the long haul, but sometimes it's easier to carry a smaller, more lightweight bottle, especially for shorter activities. In that case, here are other conversions for Iron Flask bottles in the wide mouth design:

Wide Mouth Iron Flask Water Bottle Sizes & Conversions

  • 40 oz to gallon conversion: 0.31 gallons
  • 40 oz to liter conversion: 1.2 liters
  • 22 oz to gallon conversion: 0.17 gallons
  • 22 oz to liter conversion: 0.65 liters
  • 18 oz to gallon conversion: 0.14 gallons
  • 18 oz to liter conversion: 0.53 liters
  • 14 oz to gallon conversion: 0.10 gallons
  • 14 fl oz to liter conversion: 0.4 liters

Narrow Mouth Iron Flask Water Bottle Sizes & Conversions

  • 12 oz to gallon conversion: 0.1 gallon
  • 12 oz to liter conversion: 0.35 liters
  • 16 oz to gallon conversion: 0.12 gallon
  • 16 oz to liter conversion: 0.5 liters
  • 20 oz to gallon conversion: 0.16 gallon
  • 20 oz to liter conversion: 0.6 liters
  • 24 oz to gallon conversion: 0.2 gallon
  • 24 oz to liter conversion: 0.7 liters
  • 32 ounces to gallon conversion: 0.25 gallon
  • 32 oz to liter conversion: 0.9 liters

Tips for Meeting Your Daily Water Goals

Now that you know how much water you need to drink per day and the best water bottle for your needs, here are some fun tips for tricking yourself into maintaining healthy hydration:

  • Flavor Boosters
One of the easiest and healthiest ways to boost the flavor of your water is to add fresh fruit and herbs to your bottle. Experiment with different combinations such as watermelon and cucumber slices or a splash of lemon and slices of fresh ginger.


For high-impact exercise, sports scientists and nutritionists recommend adding vitamin powder with electrolytes to your water bottle. Not only will it enhance the flavor but it will also be an easy way to incorporate multivitamins into your everyday diet.
  • Decorative Water Bottle Stickers
At Iron Flask, we make hydration fun with our line of stainless steel water bottles available in a range of eye-catching colors. To keep you motivated with your water intake, we recommend personalizing your bottle with decorative decals and stickers. Everyone in your household will know that it's your water bottle and it will also be a visually appealing reminder of your unique personal style.
  • Water Bottle Accessories
Make your Iron Flask water bottle even more convenient with practical upgrades like the paracord handle, which gives you additional storage options and easy carrying with a sturdy rope handle. You'll also be ready for any adventure with the built-in compass, whistle, and fire starter.
  • Water Drinking Apps
Another effective way to remind yourself to drink enough water is with water drinking apps, many of which are free to use. You can track your water during a period of days, weeks, and months, allowing you to follow your progress not just daily but also over time.
  • Food With High Water Content
Drinking liquids from a water bottle isn't the only way to stay hydrated. Incorporating food with high water content into your diet is one of our favorite strategies for maintaining a balanced amount of hydration in the body. Look for the juiciest fruits and vegetables such as cucumber, which has 96% water, along with watermelon, grapefruit, and zucchini.
  • Regular Exercise
Exercising regularly has lots of benefits, which include keeping you motivated to drink plenty of liquids. When you’re working up a sweat, it will probably make you thirsty, one of the strongest motivators for drinking water. To make sure you drink enough during a workout, The American Council on Exercise advises pre-hydrating 2 to 3 hours before exercising with 7 to 20 ounces of water. During your workout, try to drink 7 to 10 ounces of water every 10 to 20 minutes. After working out, they advise drinking 8 ounces no more than 30 minutes post-workout.


Now that you have all the information you need to stay hydrated, it’s time to have fun, drink H2O, and repeat!