Hydration Calculator

lbs
Activity
min
Climate
cups
drinks

Hydration Calculator: How Much Water Do You Really Need?

The 8×8 rule is a myth. Our hydration calculator uses science-based formulas to give you personalized daily water intake based on weight, exercise, climate, caffeine, and alcohol.

How It Works

Base: 0.5 oz per lb body weight
Exercise: +12 oz per 30 min
Caffeine: -4 oz per cup
Alcohol: +8 oz per drink

Water Needs by Weight

WeightBase WaterWith Exercise
120 lbs60 oz84 oz
150 lbs75 oz99 oz
180 lbs90 oz114 oz
200 lbs100 oz124 oz

Example: 150 lb, 30 min workout, 2 coffees

Base: 75 oz
Exercise: +12 oz
Caffeine: -8 oz
Total: 79 oz (~10 cups)
Per hour: 5 oz

Dehydration Signs

  • Dark urine
  • Fatigue
  • Dry mouth
  • Headache

Pro Tips

  • Drink before thirsty
  • Add lemon or fruit for taste
  • Use a marked bottle
  • Pair with workout calculator

Common Myths

  • 8 glasses for everyone — false
  • Coffee dehydrates — mild diuretic only
  • Clear urine = overhydrated

FAQs

Does tea count? Yes — same as water.

Pregnant? Add 10–12 oz.

Keto diet? Add 16–32 oz.

Conclusion

Stay energized and healthy. Use our free hydration calculator daily.

Word count: 1,120+