Target Weight Calculator
body {
font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
background-color: #f4f7f6;
color: #333;
line-height: 1.6;
margin: 0;
padding: 20px;
}
.calc-container {
max-width: 800px;
margin: 30px auto;
background-color: #ffffff;
padding: 30px;
border-radius: 8px;
box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}
h1, h2 {
color: #004a99;
text-align: center;
margin-bottom: 25px;
}
.input-section, .result-section {
margin-bottom: 30px;
padding: 20px;
border: 1px solid #e0e0e0;
border-radius: 6px;
background-color: #f8f9fa;
}
.input-group {
margin-bottom: 18px;
display: flex;
flex-direction: column;
align-items: flex-start;
}
label {
font-weight: bold;
color: #004a99;
margin-bottom: 8px;
display: block;
}
input[type="number"] {
width: calc(100% – 20px);
padding: 10px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 1rem;
margin-top: 5px;
}
button {
background-color: #28a745;
color: white;
padding: 12px 25px;
border: none;
border-radius: 5px;
font-size: 1.1rem;
cursor: pointer;
transition: background-color 0.3s ease;
display: block;
width: 100%;
margin-top: 10px;
}
button:hover {
background-color: #218838;
}
#result {
background-color: #e9ecef;
padding: 20px;
border-radius: 6px;
text-align: center;
font-size: 1.4rem;
font-weight: bold;
color: #004a99;
margin-top: 20px;
min-height: 60px;
display: flex;
align-items: center;
justify-content: center;
border: 2px dashed #004a99;
}
#result span {
color: #28a745;
}
.explanation {
margin-top: 40px;
border-top: 1px solid #e0e0e0;
padding-top: 30px;
color: #555;
}
.explanation h2 {
text-align: left;
color: #004a99;
}
.explanation p, .explanation ul {
margin-bottom: 15px;
}
.explanation li {
margin-bottom: 8px;
}
/* Responsive adjustments */
@media (max-width: 768px) {
.calc-container {
padding: 20px;
}
h1 {
font-size: 1.8rem;
}
button {
font-size: 1rem;
padding: 10px 20px;
}
#result {
font-size: 1.2rem;
}
}
Target Weight Calculator
Understanding Your Target Weight Calculation
The Target Weight Calculator helps you understand the adjustments needed to reach a specific body composition goal. It goes beyond just a simple weight number by considering body fat percentage. This is crucial because weight loss often involves losing both fat and muscle. Our calculator helps you estimate the lean mass you'll retain or need to build and the fat mass you need to lose to hit your target.
The Math Behind the Calculator:
The calculation is based on the principle of body composition:
- Total Weight = Lean Body Mass (LBM) + Fat Mass (FM)
- Lean Body Mass (LBM) includes everything that isn't fat: bones, organs, muscles, water, etc.
- Fat Mass (FM) is the total weight of fat in your body.
Steps in the Calculation:
-
Calculate Current Fat Mass (FM_current):
`FM_current = Current Weight * (Current Body Fat Percentage / 100)`
-
Calculate Current Lean Body Mass (LBM_current):
`LBM_current = Current Weight – FM_current`
-
Calculate Target Fat Mass (FM_target):
This is calculated based on your target weight and target body fat percentage.
`FM_target = Target Weight * (Target Body Fat Percentage / 100)`
-
Calculate Required Lean Body Mass (LBM_required):
This is the lean body mass you would have at your target weight and target body fat percentage.
`LBM_required = Target Weight – FM_target`
-
Determine Lean Mass Change:
`Lean Mass Change = LBM_current – LBM_required`
-
Determine Fat Mass Change:
`Fat Mass Change = FM_current – FM_target`
Interpreting the Results:
The calculator will show you:
- The amount of Fat Mass you need to lose or gain.
- The amount of Lean Body Mass you need to lose or gain (or maintain).
Typically, to improve body composition, you aim to lose fat mass and maintain or increase lean body mass. If the calculator shows a negative Lean Mass Change, it suggests that to reach your target composition, you'd need to lose lean mass along with fat mass, which is generally not the ideal scenario for health and fitness. Conversely, a positive Lean Mass Change indicates you'd need to build muscle relative to your target weight.
Use Cases:
- Weight Management: Helps individuals set realistic weight goals that focus on body composition rather than just the number on the scale.
- Fitness Training: Useful for athletes and fitness enthusiasts planning training programs to achieve specific physique goals (e.g., muscle gain, fat loss).
- Health Professionals: A tool for dietitians, personal trainers, and doctors to guide clients toward healthier body compositions.
Disclaimer: This calculator provides an estimate based on inputted data. Consult with a healthcare professional or certified fitness expert for personalized advice.
function calculateTargetWeight() {
var currentWeight = parseFloat(document.getElementById("currentWeight").value);
var targetWeight = parseFloat(document.getElementById("targetWeight").value);
var currentFatPercentage = parseFloat(document.getElementById("currentFatPercentage").value);
var targetFatPercentage = parseFloat(document.getElementById("targetFatPercentage").value);
var resultDiv = document.getElementById("result");
resultDiv.innerHTML = ""; // Clear previous results
// Input validation
if (isNaN(currentWeight) || isNaN(targetWeight) || isNaN(currentFatPercentage) || isNaN(targetFatPercentage)) {
resultDiv.innerHTML = "Please enter valid numbers for all fields.";
return;
}
if (currentWeight <= 0 || targetWeight <= 0 || currentFatPercentage < 0 || targetFatPercentage 100 || targetFatPercentage > 100) {
resultDiv.innerHTML = "Body fat percentage cannot exceed 100%.";
return;
}
if (targetWeight >= currentWeight && targetFatPercentage >= currentFatPercentage) {
resultDiv.innerHTML = "Target weight and fat percentage must represent a change from current metrics.";
return;
}
// Calculations
var fmCurrent = currentWeight * (currentFatPercentage / 100);
var lbmCurrent = currentWeight – fmCurrent;
var fmTarget = targetWeight * (targetFatPercentage / 100);
var lbmRequired = targetWeight – fmTarget;
var fatLossNeeded = fmCurrent – fmTarget;
var leanMassChange = lbmCurrent – lbmRequired;
var resultHTML = "
Your Target Composition Goals:
";
resultHTML += "To reach your target of
" + targetWeight + " kg with
" + targetFatPercentage + "% body fat:";
resultHTML += "You need to lose approximately:
" + fatLossNeeded.toFixed(2) + " kg of
Fat Mass.";
if (leanMassChange > 0.01) { // Allow for minor floating point inaccuracies
resultHTML += "You aim to maintain or build:
" + leanMassChange.toFixed(2) + " kg of Lean Body Mass.";
resultHTML += "This requires a focus on muscle retention/growth alongside fat loss.";
} else if (leanMassChange < -0.01) {
resultHTML += "You would need to lose approximately:
" + Math.abs(leanMassChange).toFixed(2) + " kg of Lean Body Mass.";
resultHTML += "Consider if this is aligned with your health and fitness objectives.";
} else {
resultHTML += "Your Lean Body Mass is projected to remain relatively stable.";
}
resultDiv.innerHTML = resultHTML;
}