#sweat-rate-calculator-wrapper h2 { color: #0056b3; margin-top: 0; margin-bottom: 20px; font-size: 28px; text-align: center; }
#sweat-rate-calculator-wrapper .input-group { margin-bottom: 20px; }
#sweat-rate-calculator-wrapper label { display: block; font-weight: 600; margin-bottom: 8px; font-size: 15px; color: #444; }
#sweat-rate-calculator-wrapper input[type="number"],
#sweat-rate-calculator-wrapper select { width: 100%; padding: 12px; border: 1px solid #ccc; border-radius: 6px; font-size: 16px; box-sizing: border-box; }
#sweat-rate-calculator-wrapper .flex-container { display: flex; gap: 15px; flex-wrap: wrap; }
#sweat-rate-calculator-wrapper .flex-item { flex: 1; min-width: 200px; }
#sweat-rate-calculator-wrapper button { width: 100%; background-color: #0056b3; color: white; padding: 15px; border: none; border-radius: 6px; font-size: 18px; font-weight: bold; cursor: pointer; transition: background 0.3s; margin-top: 10px; }
#sweat-rate-calculator-wrapper button:hover { background-color: #004494; }
#sweat-rate-calculator-wrapper .result-box { margin-top: 25px; padding: 20px; border-radius: 8px; background-color: #f0f7ff; border: 1px solid #d0e3f7; display: none; }
#sweat-rate-calculator-wrapper .result-box h3 { margin-top: 0; color: #0056b3; font-size: 20px; }
#sweat-rate-calculator-wrapper .metric-value { font-size: 24px; font-weight: bold; color: #d9534f; margin: 10px 0; }
#sweat-rate-calculator-wrapper .unit-toggle { background: #f8f9fa; padding: 10px; border-radius: 6px; margin-bottom: 20px; text-align: center; border: 1px solid #eee; }
#sweat-rate-calculator-wrapper .article-content { margin-top: 40px; border-top: 2px solid #eee; pt: 30px; }
#sweat-rate-calculator-wrapper .article-content h3 { color: #222; margin-top: 25px; }
#sweat-rate-calculator-wrapper .example-box { background: #fff9e6; padding: 15px; border-left: 5px solid #ffcc00; margin: 20px 0; font-style: italic; }
var currentUnitSystem = 'metric';
function toggleUnits(system) {
currentUnitSystem = system;
var lblPre = document.getElementById('lbl-pre-weight');
var lblPost = document.getElementById('lbl-post-weight');
var lblFluid = document.getElementById('lbl-fluid');
var lblUrine = document.getElementById('lbl-urine');
var preWeight = document.getElementById('preWeight');
var postWeight = document.getElementById('postWeight');
var fluidIntake = document.getElementById('fluidIntake');
var urineOutput = document.getElementById('urineOutput');
if (system === 'metric') {
lblPre.innerHTML = "Pre-Exercise Weight (kg)";
lblPost.innerHTML = "Post-Exercise Weight (kg)";
lblFluid.innerHTML = "Fluid Intake During (ml)";
lblUrine.innerHTML = "Urine Output (ml)";
preWeight.placeholder = "e.g. 75.0";
postWeight.placeholder = "e.g. 74.2";
} else {
lblPre.innerHTML = "Pre-Exercise Weight (lbs)";
lblPost.innerHTML = "Post-Exercise Weight (lbs)";
lblFluid.innerHTML = "Fluid Intake During (oz)";
lblUrine.innerHTML = "Urine Output (oz)";
preWeight.placeholder = "e.g. 165.0";
postWeight.placeholder = "e.g. 163.5";
}
}
function calculateSweatRate() {
var preW = parseFloat(document.getElementById('preWeight').value);
var postW = parseFloat(document.getElementById('postWeight').value);
var fluid = parseFloat(document.getElementById('fluidIntake').value) || 0;
var urine = parseFloat(document.getElementById('urineOutput').value) || 0;
var mins = parseFloat(document.getElementById('duration').value);
if (isNaN(preW) || isNaN(postW) || isNaN(mins) || mins <= 0) {
alert("Please enter valid numbers for weight and duration.");
return;
}
var totalLossValue = 0;
var hourlyRateValue = 0;
var unitWeight = currentUnitSystem === 'metric' ? 'ml' : 'oz';
var weightToFluidFactor = currentUnitSystem === 'metric' ? 1000 : 16; // 1kg = 1000ml, 1lb = 16oz
// Weight Difference converted to fluid volume
var weightDiff = preW – postW;
var weightLossInFluid = weightDiff * weightToFluidFactor;
// Total fluid loss = Weight Loss (in volume) + Fluid Consumed – Urine
totalLossValue = weightLossInFluid + fluid – urine;
// Hourly rate
var hours = mins / 60;
hourlyRateValue = totalLossValue / hours;
// Update UI
document.getElementById('result').style.display = 'block';
document.getElementById('totalLoss').innerHTML = Math.round(totalLossValue) + " " + unitWeight;
document.getElementById('hourlyRate').innerHTML = Math.round(hourlyRateValue) + " " + unitWeight + " / hour";
// Advice logic
var advice = "";
if (hourlyRateValue (currentUnitSystem === 'metric' ? 1500 : 51)) {
advice = "You have a high sweat rate. Focus on electrolyte replacement and a structured hydration plan.";
} else {
advice = "You have a moderate sweat rate. Standard hydration protocols should work well for you.";
}
document.getElementById('hydration-advice').innerHTML = advice;
// Scroll to result
document.getElementById('result').scrollIntoView({ behavior: 'smooth', block: 'nearest' });
}
Sweat Rate Calculator
Your Hydration Results
Total Fluid Loss: 0
Sweat Rate Per Hour: 0
How to Calculate Sweat Rate Per Hour
Understanding your specific sweat rate is the "holy grail" of endurance performance. It allows you to tailor your hydration strategy to your body's specific needs, preventing both dehydration and hyponatremia (over-hydration).
The calculation measures the difference in body mass before and after exercise, adjusted for fluid intake and waste output. This provides the most accurate estimate of how much fluid your body loses through perspiration in a specific environment.
The Sweat Rate Formula
To find your sweat rate per hour, use the following physics-based formula:
Sweat Rate (L/hr) = [(Weight Before – Weight After) + Fluid Intake – Urine Output] / (Minutes / 60)
Why You Should Measure Your Sweat Rate
- Prevent Fatigue: Even 2% dehydration can lead to a significant drop in aerobic performance and cognitive function.
- Avoid GI Distress: Drinking too much (more than your sweat rate) can lead to sloshing in the stomach and nausea.
- Environment Specificity: Your sweat rate changes based on humidity, temperature, and intensity. Calculating it in different seasons is essential.
Real-World Example (Metric):
If you weigh 70kg before a 60-minute run, 69.2kg after, drink 500ml of water, and don't use the bathroom:
1. Weight loss = 0.8kg (800ml fluid equivalent)
2. Fluid added = 500ml
3. Total loss = 800 + 500 = 1,300ml
4. Sweat Rate = 1,300ml / hour.
If you weigh 70kg before a 60-minute run, 69.2kg after, drink 500ml of water, and don't use the bathroom:
1. Weight loss = 0.8kg (800ml fluid equivalent)
2. Fluid added = 500ml
3. Total loss = 800 + 500 = 1,300ml
4. Sweat Rate = 1,300ml / hour.
Pro Tips for Accuracy
For the most accurate results, weigh yourself "dry" (without clothing) before and after your workout. Sweat trapped in clothing can add weight and skew your post-exercise measurement. Ensure you use the same scale for both readings to eliminate calibration errors.