Percentages are a fundamental part of mathematics and everyday life, used to express a proportion of a whole as a fraction of 100. The term "percent" literally means "per hundred." Whether you're calculating discounts, understanding statistics, or analyzing financial data, a solid grasp of percentages is invaluable.
This calculator helps you quickly solve the most common percentage problems. Below, you'll find tools for four key types of percentage calculations, along with explanations and examples for each.
1. What is X% of Y?
This calculation helps you find a specific portion of a total value. For example, if you want to know what 15% of 200 is, this is the tool you'd use.
2. X is what percent of Y?
Use this to determine what percentage one number represents of another. For instance, if you scored 45 out of 50 on a test, this calculation tells you your percentage score.
3. Percentage Change (Increase or Decrease)
This calculation determines the percentage difference between an original value and a new value. It's useful for tracking growth, decline, or comparing two points in time. A positive result indicates an increase, while a negative result indicates a decrease.
4. Value After Percentage Change
If you know an original value and a percentage change (increase or decrease), this tool will tell you the resulting new value. For example, if a product costs $50 and increases by 10%, what's the new price?
Understanding and calculating percentages is a vital skill. Use the calculator above to practice and solve your percentage problems quickly and accurately!
.calculator-container {
font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
background-color: #f9f9f9;
padding: 20px;
border-radius: 8px;
box-shadow: 0 2px 10px rgba(0,0,0,0.1);
max-width: 700px;
margin: 20px auto;
color: #333;
}
.calculator-container h2, .calculator-container h3 {
color: #0056b3;
text-align: center;
margin-bottom: 15px;
}
.calculator-container p {
line-height: 1.6;
margin-bottom: 10px;
}
.calculator-section {
background-color: #ffffff;
border: 1px solid #e0e0e0;
border-radius: 5px;
padding: 15px;
margin-bottom: 20px;
}
.calculator-section label {
display: block;
margin-bottom: 8px;
font-weight: bold;
color: #555;
}
.calculator-section input[type="number"] {
width: calc(100% – 22px);
padding: 10px;
margin-bottom: 10px;
border: 1px solid #ccc;
border-radius: 4px;
box-sizing: border-box;
}
.calculator-section button {
background-color: #007bff;
color: white;
padding: 10px 15px;
border: none;
border-radius: 4px;
cursor: pointer;
font-size: 16px;
transition: background-color 0.2s ease-in-out;
}
.calculator-section button:hover {
background-color: #0056b3;
}
.calculator-result {
margin-top: 15px;
padding: 10px;
background-color: #e9f7ef;
border: 1px solid #d4edda;
border-radius: 4px;
font-weight: bold;
color: #155724;
min-height: 20px;
display: flex;
align-items: center;
}
.calculator-result:empty {
background-color: #f9f9f9;
border: 1px solid #e0e0e0;
color: #333;
}
function calculatePercentOfNumber() {
var percentage = parseFloat(document.getElementById('calc1_percentage').value);
var totalValue = parseFloat(document.getElementById('calc1_totalValue').value);
var resultDiv = document.getElementById('calc1_result');
if (isNaN(percentage) || isNaN(totalValue)) {
resultDiv.innerHTML = "Please enter valid numbers for both fields.";
return;
}
var result = (percentage / 100) * totalValue;
resultDiv.innerHTML = percentage + "% of " + totalValue + " is: " + result.toFixed(2) + "";
}
function calculateWhatPercent() {
var part = parseFloat(document.getElementById('calc2_part').value);
var whole = parseFloat(document.getElementById('calc2_whole').value);
var resultDiv = document.getElementById('calc2_result');
if (isNaN(part) || isNaN(whole)) {
resultDiv.innerHTML = "Please enter valid numbers for both fields.";
return;
}
if (whole === 0) {
resultDiv.innerHTML = "The 'Whole' value cannot be zero.";
return;
}
var result = (part / whole) * 100;
resultDiv.innerHTML = part + " is " + result.toFixed(2) + "% of " + whole;
}
function calculatePercentageChange() {
var originalValue = parseFloat(document.getElementById('calc3_originalValue').value);
var newValue = parseFloat(document.getElementById('calc3_newValue').value);
var resultDiv = document.getElementById('calc3_result');
if (isNaN(originalValue) || isNaN(newValue)) {
resultDiv.innerHTML = "Please enter valid numbers for both fields.";
return;
}
if (originalValue === 0) {
resultDiv.innerHTML = "The 'Original Value' cannot be zero for percentage change calculation.";
return;
}
var change = newValue – originalValue;
var percentageChange = (change / originalValue) * 100;
var changeType = (percentageChange >= 0) ? "increase" : "decrease";
resultDiv.innerHTML = "The percentage " + changeType + " is: " + percentageChange.toFixed(2) + "%";
}
function calculateValueAfterChange() {
var originalValue = parseFloat(document.getElementById('calc4_originalValue').value);
var percentageChange = parseFloat(document.getElementById('calc4_percentageChange').value);
var resultDiv = document.getElementById('calc4_result');
if (isNaN(originalValue) || isNaN(percentageChange)) {
resultDiv.innerHTML = "Please enter valid numbers for both fields.";
return;
}
var multiplier = 1 + (percentageChange / 100);
var newValue = originalValue * multiplier;
var changeType = (percentageChange >= 0) ? "increase" : "decrease";
resultDiv.innerHTML = "After a " + percentageChange.toFixed(2) + "% " + changeType + ", the new value is: " + newValue.toFixed(2) + "";
}