Oral Rehydration Plan Helper

A wellness utility to estimate daily fluid needs and plan oral rehydration. Calculates baseline hydration, activity sweat loss, and illness replacement needs. Supports metric (mL, L, kg) and US customary units (fl oz, lb). Everything runs in your browser—no data sent online.

Educational only, not medical advice. For severe dehydration, vomiting, or medical conditions, seek immediate professional care.

Calculate Your Fluid Plan

Units:

Precision:

Body Weight

Enter your current weight. Accepts decimals with dot or comma.

Activity Level Today

Adjusts for sweat loss from physical activity.

Additional Illness/Replacement Need

Estimates extra fluid to replace losses from illness. Not for severe cases—seek care.

Your Daily Fluid Plan

Total Daily Target

—

Baseline (Weight)

—

Activity Adjustment

—

Illness Replacement

—

Per Hour Guide

—

Interpretation & Tips

Enter your details and calculate to see personalized guidance.
This is a wellness estimate, not a medical prescription.
Spread intake throughout the day; don't drink large amounts at once.

Understanding Oral Rehydration

Proper hydration is essential for energy, temperature regulation, and organ function. This tool helps you build a personalized, non‑medical fluid plan for daily wellness or mild, temporary conditions. It estimates baseline needs from your weight, adds activity‑based sweat loss, and includes optional replacement for illness‑related losses (like mild diarrhea or fever sweat).

How to Use This Tool

Enter your current weight. Use the unit toggle if you prefer pounds.
Select your activity level for the day—this adjusts for sweat loss.
If you are experiencing mild illness (e.g., slight diarrhea, fever), choose the appropriate additional replacement level.
Click Calculate Plan to see your total daily target and an hourly sipping guide.
Use the Copy Result button to save the plan for your notes.

Realistic Examples

Scenario	Weight	Activity	Illness	Total Daily Target (approx.)
Office worker, well	70 kg (154 lb)	Light	None	2.5–2.8 L (84–95 fl oz)
Gardening in heat, mild diarrhea	85 kg (187 lb)	Moderate	Mild	3.8–4.2 L (128–142 fl oz)
Endurance athlete, heavy sweat	60 kg (132 lb)	Very High	None	3.2–3.6 L (108–122 fl oz)

Typical Ranges & Pitfalls

Common Daily Intake Ranges

• General wellness: 30–40 mL per kg of body weight
• Moderate activity: +10–20% above baseline
• Hot environment: +500–1000 mL (17–34 fl oz)
• Mild illness replacement: +500–1500 mL (17–51 fl oz)

Measurement & Safety Checklist

• Weigh yourself in the morning after bathroom, before eating.
• Spread fluid intake evenly; avoid >1 L (34 fl oz) per hour.
• If you have kidney, heart, or liver conditions, consult a doctor.
• Seek immediate care for severe vomiting, confusion, no urine for 8+ hours, or rapid weight loss.

Electrolyte Consideration Helper

When fluid losses are high (sweat, diarrhea), electrolytes matter. Adjust the slider to see when plain water might not be enough.

Estimated Total Daily Fluid Loss (from activity + illness) 0 mL

Low (<500 mL) Moderate (500‑1500 mL) High (>1500 mL)

Adjust the slider above to see guidance.

Frequently Asked Questions

How accurate is this calculator?

It uses standard wellness formulas for baseline hydration (30‑35 mL/kg) and multiplies by an activity factor. It provides a reasonable non‑medical estimate for general planning. Individual needs vary based on metabolism, climate, and health status.

What’s the difference between “baseline” and “activity adjustment”?

Baseline is the fluid your body needs at rest for basic functions. Activity adjustment adds an estimate for sweat loss during physical exertion. The activity factors are simplified multipliers (1.0‑1.8) based on exercise intensity and duration.

Can I use this tool for severe diarrhea or vomiting?

No. This tool is for mild, temporary conditions only. Severe fluid loss requires medical assessment and possibly intravenous rehydration. Seek professional care if you have dizziness, rapid heartbeat, sunken eyes, or cannot keep fluids down.

Why does the result include an hourly guide?

Sipping fluids steadily throughout the day improves absorption and reduces the risk of over‑hydration or stomach discomfort. The hourly guide divides your total target by 16 waking hours as a practical reminder.

How should I measure my weight for the best accuracy?

Weigh yourself in the morning after using the bathroom and before eating or drinking, wearing minimal clothing. Use the same scale each time. For tracking changes, daily weights at the same time are helpful.

Formulas & Assumptions

• Baseline fluid (mL) = Weight (kg) × 30 (lower range) to 35 (upper range) mL/kg. The calculator uses 32.5 mL/kg as a midpoint.
• Activity adjustment = Baseline × (Activity Factor − 1.0). Factors: Sedentary=1.0, Light=1.2, Moderate=1.4, High=1.6, Very High=1.8.
• Illness replacement = Fixed addition based on selection: None=0, Mild=500 mL, Moderate=1000 mL, Significant=1500 mL.
• Total target = Baseline + Activity adjustment + Illness replacement.
• Hourly guide = Total target ÷ 16 (assumed waking hours).
• Unit conversions: 1 kg = 2.20462 lb, 1 L = 33.814 fl oz, 1 fl oz ≈ 29.5735 mL.
• Rounding: Final results are rounded to the selected decimal place. Intermediate values use full precision.

Disclaimer: For informational and educational purposes only. Estimates depend on your inputs and simplifying assumptions. This tool is not medical advice and does not diagnose or treat any condition. If you have symptoms, abnormal readings, or urgent concerns, contact a qualified healthcare professional.

Sources & References (Concepts):

Common unit conversions and measurement best practices; Typical wellness metric ranges and public health guidance concepts; General nutrition and hydration guidance concepts; Electrolyte replacement principles for non‑medical settings.

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