Hydration Status Calculator 2025: Complete Guide to Fluid Balance
Hydration is critical for thermoregulation, cognition, and organ function. Even 2% body weight loss from dehydration impairs performance. Our Hydration Status Calculator combines urine color, specific gravity, weight change, and clinical signs for accurate assessment. This guide covers physiology, thresholds, and rehydration strategies.
Why Hydration Matters
Water = 60% of body weight. Dehydration reduces plasma volume → ↑ heart rate, ↓ stroke volume. Overhydration (hyponatremia) risks cerebral edema.
Assessment Methods
1. Urine Color Chart (Armstrong Scale)
- 1–3: Well hydrated
- 4–5: Minimal dehydration
- 6–8: Significant dehydration
2. Urine Specific Gravity (USG)
- 1.005–1.020: Normal
- 1.021–1.030: Dehydrated
- <1.005: Overhydrated
3. Body Weight Change
Most sensitive acute marker:
% Change = [(Pre − Post) / Pre] × 100
4. Clinical Signs
| Severity | Signs |
|---|---|
| Mild (3–5%) | Thirst, dry mouth |
| Moderate (6–9%) | Dizziness, headache, tachycardia |
| Severe (>10%) | Confusion, oliguria, shock |
Pediatric Dehydration (WHO Scale)
- No Dehydration: Normal eyes, moist mucosa, normal skin turgor
- Some (5%): Restless, sunken eyes, drinks eagerly
- Severe (10%): Lethargic, very sunken eyes, unable to drink
Rehydration Guidelines
- Mild: 500 mL water + electrolytes over 1 hour
- Moderate: Oral rehydration solution (ORS) 50–100 mL/kg over 4 hours
- Severe: IV fluids (20 mL/kg bolus)
Daily Fluid Needs
- Adults: 35–40 mL/kg/day
- Athletes: +500–1000 mL/hour exercise
- Elderly: Monitor intake (reduced thirst sensation)
Limitations
- Urine color affected by vitamins, beets, medications
- USG invalid post-diuretic or in diabetes insipidus
- Weight change includes glycogen, food
Advanced Tips
- Pre-exercise: 5–7 mL/kg 4 hours prior
- During: 400–800 mL/hour
- Post: 1.5 L fluid per kg lost
- Pair with Symptom Checker
FAQs
Can I be dehydrated with clear urine? Yes, if overhydrated or post-diuretic.
Is dark urine always dehydration? No. Check for blood, liver issues.
How much water to drink daily? 2.7 L (women), 3.7 L (men) including food.
Conclusion
Accurate hydration assessment prevents heat illness, kidney stones, and cognitive decline. Use our 2025 Hydration Status Calculator daily — especially in heat, illness, or sport. Always seek medical care for severe symptoms.
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