How many oz of water should you drink per day?

A common recommendation is to drink half your body weight in ounces per day. For a 150 lb person, that is 75 oz (about 2.2 liters). The National Academies of Sciences recommends approximately 91 oz (2.7 liters) for women and 125 oz (3.7 liters) for men total fluid intake, including water from food.

How many liters of water should you drink per day?

General recommendations are 2.7 liters (91 oz) per day for women and 3.7 liters (125 oz) per day for men, including water from beverages and food. About 20% of water intake comes from food, so pure water intake targets are approximately 2 liters for women and 3 liters for men.

How much water should a 150 lb person drink?

Using the weight-based formula (body weight lbs ÷ 2 = oz per day), a 150 lb person should drink approximately 75 oz of water per day, which equals about 2.2 liters or roughly nine 8 oz glasses. Increase this by 12–16 oz for every 30 minutes of exercise or in hot weather.

Daily Hydration Guide: How Much Water to Drink in oz and Liters

The 8×8 Rule and the Weight-Based Formula

The widely cited 8×8 rule — drink eight 8-ounce glasses (64 oz / 1.9 liters) per day — is a simple starting point but does not account for individual body size. A 100 lb person and a 250 lb person have very different hydration needs.

A more personalized approach is the weight-based formula: drink approximately half your body weight in ounces per day. A 150 lb person targets 75 oz; a 200 lb person targets 100 oz. Factors that increase your needs include:

Exercise: Add 12–16 oz per 30 minutes of vigorous activity.
Heat and humidity: Add 8–16 oz on hot days or in humid environments.
High altitude: Increase by 16–32 oz above 8,000 feet (2,400 m).
Pregnancy: The National Academy recommends adding 10 oz (300 ml) per day.
Breastfeeding: Add approximately 26 oz (770 ml) per day.

Daily Water Needs by Body Weight

Body Weight (lbs)	Body Weight (kg)	Daily Water (oz)	Daily Water (liters)	Approx. 8 oz Glasses
100 lbs	45 kg	50 oz	1.5 L	6 glasses
120 lbs	54 kg	60 oz	1.8 L	7.5 glasses
140 lbs	64 kg	70 oz	2.1 L	8.75 glasses
150 lbs	68 kg	75 oz	2.2 L	9.4 glasses
160 lbs	73 kg	80 oz	2.4 L	10 glasses
180 lbs	82 kg	90 oz	2.7 L	11.25 glasses
200 lbs	91 kg	100 oz	3.0 L	12.5 glasses
220 lbs	100 kg	110 oz	3.3 L	13.75 glasses
250 lbs	113 kg	125 oz	3.7 L	15.6 glasses

Common Container Sizes for Daily Tracking

Knowing how many containers you need to drink each day makes tracking much easier. Fill and finish your containers at set times rather than sipping randomly throughout the day.

Container	Size (oz)	Size (ml)	Needed for 75 oz/day	Needed for 100 oz/day
Standard glass	8 oz	237 ml	9–10 glasses	12–13 glasses
Standard water bottle	16.9 oz	500 ml	4.4 bottles	5.9 bottles
Large water bottle	24 oz	710 ml	3.1 bottles	4.2 bottles
32 oz bottle (Nalgene)	32 oz	946 ml	2.3 bottles	3.1 bottles
40 oz tumbler (Stanley)	40 oz	1,183 ml	1.9 tumblers	2.5 tumblers
1 liter bottle	33.8 oz	1,000 ml	2.2 bottles	3.0 bottles
Half-gallon jug	64 oz	1,893 ml	1.2 jugs	1.6 jugs

Signs of Dehydration and Overhydration

The best indicator of adequate hydration is urine color: pale yellow (like lemonade) indicates good hydration. Dark yellow or amber indicates dehydration. Colorless urine can indicate overhydration, which can dilute electrolytes.

Mild dehydration: thirst, dry mouth, slightly dark urine, reduced energy.
Moderate dehydration: headache, dizziness, reduced concentration, dark amber urine.
Overhydration risk: Drinking more than 1 liter per hour for extended periods can dilute sodium (hyponatremia) — relevant for endurance athletes.

Use our volume converter to convert between fluid ounces, milliliters, and liters for any hydration tracking system.