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Water Intake Calculator
≈ 101 fl oz
Why Most People Are Dehydrated
You're probably not drinking enough water. Most people walk around mildly dehydrated all day without realizing it. Headaches? Could be water. Tired at 3pm? Might be water. Dry skin? Definitely water.
💡 Real Talk from Sarah Jenkins, RD
The "8 glasses a day" rule is too generic. A 120 lb woman needs different hydration than a 200 lb man who exercises daily. Use your body weight and activity level. And check your urine color—it's the easiest hydration test. Pale yellow = you're good. Dark yellow = drink more.
How Much Do You Actually Need?
Base formula: 0.033 liters per kg of body weight (or half your weight in ounces)
- 70 kg (154 lbs) → 2.3 L (78 oz) base
- 80 kg (176 lbs) → 2.64 L (89 oz) base
- 90 kg (198 lbs) → 3 L (101 oz) base
Add more if:
- You exercise: Add 0.5-1L per hour of workout
- Hot/humid climate: Add 20-30% more
- Pregnant/breastfeeding: Add 1L extra
- Sick (fever/vomiting): Drink more to replace losses
⚠️ Common Mistake: Waiting until you're thirsty
By the time you feel thirsty, you're already dehydrated. Your body is 1-2% low on fluids. For athletes, this means measurable performance drop. Sip water consistently throughout the day, don't chug it all at once.
The Urine Test (Best Indicator)
Forget complicated formulas. Look at your pee:
- Clear: Overhydrated (ease up)
- Pale yellow: Perfect ✅
- Dark yellow: Dehydrated (drink more)
- Amber/brown: Severely dehydrated (drink now!)
What Counts as Water?
Fully counts:
- Plain water (obviously)
- Unsweetened tea/coffee (yes, caffeine still hydrates)
- Sparkling water
- Water-rich foods (watermelon, cucumber, soup)
Doesn't count (or counts less):
- Alcohol (dehydrates you)
- Sugary drinks (adds calories, not ideal)
- Excessive caffeine (>400mg/day can dehydrate)
Practical Tips
- Carry a water bottle: You'll drink more if it's visible
- Drink a glass when you wake up: You're dehydrated after sleeping
- Before meals: Helps with digestion and portion control
- Set reminders: Phone alarm every 2 hours if needed
Reviewed by Sarah Jenkins, RD
Registered Dietitian & Sports Nutritionist
Sarah helps clients optimize hydration for performance and health.
Frequently Asked Questions
How much water should I drink per day?
General rule: 0.033 liters per kg of body weight (or half your body weight in ounces). A 70 kg (154 lb) person needs about 2.3 liters (78 oz) base. Add more if you exercise (extra 0.5-1L per hour of workout), live in hot climate (+20-30%), or are pregnant/breastfeeding. Your urine color is the best indicator: pale yellow = good, dark yellow = drink more.
Can I drink too much water?
Yes, but it's rare. Drinking excessive water (>1L per hour for extended periods) can cause hyponatremia (low sodium). Symptoms: nausea, headache, confusion. For most people, drinking when thirsty and checking urine color works fine. Athletes doing long endurance events need electrolytes, not just water.
Does coffee/tea count toward water intake?
Yes! Despite being mild diuretics, coffee and tea still contribute to hydration. Research shows regular coffee drinkers don't get dehydrated from it. Plain water is best, but unsweetened tea/coffee counts. Avoid counting sugary drinks, alcohol, or excessive caffeine (>400mg/day).