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Water Intake Calculator

Stay properly hydrated every day

Daily Water Intake

100 oz

Liters

3 L

Cups

13 cups

Bottles

5.9 bottles

Units
lbs

Daily Water Intake

100

oz

3 liters

Cups

13

8oz cups

Bottles

5.9

16.9oz bottles

Per Hour

6.3

oz/hour

Daily Hydration Goal

Progress100 oz / 100 oz
Water/Tea70 oz (70%)
Food20 oz (20%)
Other Beverages10 oz (10%)

Frequently Asked Questions

Q

How much water should I drink per day?

General rule: Half your body weight in ounces. 160 lbs = 80 oz (10 cups). 200 lbs = 100 oz (12.5 cups). The "8 glasses" (64 oz) advice is a minimum. Active people and those in hot climates need more.

  • Formula: Body weight (lbs) ÷ 2 = ounces of water
  • Add 12-16 oz for every 30 min of exercise
  • Hot climate: Add 20-30% more water
  • Urine color is best indicator: Light yellow = hydrated
Body WeightBase Water NeedActive/Hot ClimateCups per Day
120 lbs (54 kg)60 oz75-90 oz8-11 cups
150 lbs (68 kg)75 oz95-115 oz9-14 cups
180 lbs (82 kg)90 oz110-135 oz11-17 cups
200 lbs (91 kg)100 oz125-150 oz12-19 cups
Q

What are signs of dehydration?

Early signs: Thirst, dark yellow urine, dry mouth, fatigue. Moderate: Headache, dizziness, decreased urination, muscle cramps. Severe: Confusion, rapid heartbeat, sunken eyes, very dark urine. Check urine color - pale yellow is ideal.

  • Mild (1-2% body water loss): Thirst, reduced focus, fatigue
  • Moderate (3-5%): Headache, dizziness, dry skin, muscle weakness
  • Severe (6%+): Confusion, rapid pulse, fainting - seek medical help
  • Urine color check: Clear=over-hydrated, Light yellow=good, Dark=dehydrated

By the time you feel thirsty, you're already 1-2% dehydrated. Performance drops at just 2% dehydration. Keep a water bottle nearby and sip throughout the day rather than drinking large amounts at once.

Q

Does coffee and tea count toward water intake?

Yes, coffee and tea do hydrate you despite caffeine's mild diuretic effect. Studies show the hydration from the water outweighs caffeine's effect. However, water is still the best choice - no calories, no additives.

  • Coffee/tea: Yes, counts toward hydration
  • Milk: Yes, actually hydrates better than water (electrolytes)
  • Juice: Yes, but watch sugar content
  • Soda: Technically yes, but high sugar is unhealthy
  • Alcohol: No - net dehydrating effect
  • Sports drinks: Yes, good for intense exercise (electrolytes)
BeverageHydrating?Notes
WaterBestNo calories, ideal choice
Coffee/TeaYesCaffeine effect is minimal
MilkYesGood electrolytes, calories
Fruit JuiceYesHigh in sugar
AlcoholNoCauses net dehydration
Q

When should I drink more water?

Increase intake: During exercise (16-20 oz per hour), hot/humid weather (+20-30%), at altitude (+8-16 oz/day), when sick (especially fever/diarrhea), pregnant (+10-16 oz), breastfeeding (+32 oz). Also after alcohol consumption.

  • Exercise: 16-20 oz per hour of activity
  • Hot weather: Add 20-30% to base intake
  • Illness with fever: Extra 8 oz per degree above normal
  • High altitude: Add 8-16 oz per day above 5,000 ft
  • Pregnancy: Add 10-16 oz daily
  • Breastfeeding: Add 32 oz (4 cups) daily
  • After alcohol: 1 glass water per alcoholic drink
Q

Can you drink too much water?

Yes, water intoxication (hyponatremia) is rare but dangerous. It dilutes sodium in blood. Risk is highest in endurance athletes drinking excessive water without electrolytes. Symptoms: Nausea, headache, confusion, seizures.

  • Hyponatremia: Dangerously low blood sodium
  • Risk: Drinking gallons in short time without electrolytes
  • Endurance athletes: Use sports drinks for events 60+ minutes
  • Symptoms: Nausea, headache, confusion, swelling
  • Normal drinking (responding to thirst) is very safe
  • Don't force excessive water intake

Water intoxication is extremely rare in normal circumstances. It mainly affects marathon runners or those in water-drinking contests. For normal people, kidneys can process about 1 liter per hour. Drink when thirsty and you'll be fine.

Q

How can I drink more water throughout the day?

Tips: Keep a water bottle with you always, set hourly reminders, drink before each meal, use a marked water bottle with time goals, add fruit for flavor, drink a glass upon waking, replace one soda/coffee with water daily.

  • Keep water bottle visible at desk/in car
  • Drink 1-2 cups first thing in morning
  • Drink a glass before every meal
  • Use apps like WaterMinder or Plant Nanny for reminders
  • Mark water bottle with time goals
  • Add lemon, cucumber, or berries for flavor
  • Replace one daily soda/juice with water
  • Drink water with every medication

Example Calculations

1160 lb Person, Moderate Activity, Moderate Climate

Inputs

Weight160 lbs
Activity LevelModerate
ClimateModerate

Result

Daily Water Intake100 oz (3.0 L)
Cups (8 oz)13 cups
Water Bottles5.9 bottles
Per Hour (16 waking hrs)6.3 oz/hour

Base = 160 x 0.5 = 80 oz. Activity adjustment = 80 x 1.25 = 100 oz. Climate adjustment = 100 x 1.0 = 100 oz. Liters = 100 x 0.0296 = 3.0 L. Cups = 100 / 8 = 13.

2200 lb Active Person in Hot Climate

Inputs

Weight200 lbs
Activity LevelActive
ClimateHot

Result

Daily Water Intake161 oz (4.8 L)
Cups (8 oz)20 cups
Water Bottles9.5 bottles
Per Hour (16 waking hrs)10.1 oz/hour

Base = 200 x 0.5 = 100 oz. Activity adjustment = 100 x 1.4 = 140 oz. Climate adjustment = 140 x 1.15 = 161 oz. Liters = 161 x 0.0296 = 4.8 L. Cups = 161 / 8 = 20.

Formulas Used

Base Water Intake

Base Ounces = Weight (lbs) x 0.5

The base daily water intake is half your body weight in ounces.

Where:

Weight (lbs)= Your body weight in pounds
0.5= Half-ounce per pound of body weight

Adjusted Water Intake

Daily Ounces = Base Ounces x Activity Multiplier x Climate Multiplier

The base amount is adjusted for activity level and climate conditions.

Where:

Activity Multiplier= 1.0 (sedentary), 1.12 (light), 1.25 (moderate), 1.4 (active), 1.55 (athlete)
Climate Multiplier= 0.95 (cool), 1.0 (moderate), 1.15 (hot)

The Importance of Hydration

Water makes up about 60% of your body weight and plays a role in virtually every bodily function.

Proper hydration supports digestion, nutrient absorption, circulation, temperature regulation, and cognitive function.

Even mild dehydration (1-2% of body weight) can impair mood, memory, and physical performance.

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Last Updated: Feb 12, 2026

This calculator is provided for informational and educational purposes only. Results are estimates and should not be considered professional financial, medical, legal, or other advice. Always consult a qualified professional before making important decisions. UseCalcPro is not responsible for any actions taken based on calculator results.

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