How to Calculate Percentage in Excel: Formulas and Examples
Calculating percentages in Microsoft Excel is one of the most fundamental skills for data analysis, budgeting, and reporting. Unlike a standard calculator, Excel handles percentages as decimal values. For example, 10% is stored as 0.10. To display it as a percentage, you simply apply the "Percent Style" formatting.
Excel Percentage Calculation Tool
Use the calculators below to find the specific formula you need for your spreadsheet.
In Excel, the basic formula to find a percentage is =Part/Total. If you have a goal of 500 sales and you have achieved 350, the formula in cell C1 would be =A1/B1 (where A1 is 350 and B1 is 500). To make this look like "70%", you must go to the Home tab and click the % symbol in the Number group.
Calculating Percentage Change
To track growth or decline, use the formula: =(New_Value - Old_Value) / Old_Value.
Example: If your January revenue was 1,000 and February was 1,200:
=(1200 - 1000) / 1000 = 0.20 (or 20% increase).
How to Increase or Decrease a Number by a Percentage
If you want to increase a price by 10%, you don't just add 10. You multiply the original price by 1.10.
Increase Formula:=Amount * (1 + %)
Decrease Formula:=Amount * (1 - %)
For a 15% discount on a $100 item: =100 * (1 - 0.15) which equals $85.
Calculating Percentage of a Grand Total
If you have a list of items and want to see what percentage each item contributes to the sum, use an absolute cell reference for the total.
Formula: =B2/$B$10 The dollar signs ($) lock the reference to the total so you can drag the formula down the column without the reference shifting.
function calculateBasic() {
var part = parseFloat(document.getElementById('basicPart').value);
var total = parseFloat(document.getElementById('basicTotal').value);
var resultDiv = document.getElementById('basicResult');
if (isNaN(part) || isNaN(total) || total === 0) {
resultDiv.style.display = 'block';
resultDiv.innerHTML = 'Please enter valid numbers. Total cannot be zero.';
return;
}
var percentage = (part / total) * 100;
resultDiv.style.display = 'block';
resultDiv.innerHTML = 'Result: ' + percentage.toFixed(2) + '%Excel Formula: =' + part + '/' + total + '';
}
function calculateChange() {
var oldV = parseFloat(document.getElementById('oldVal').value);
var newV = parseFloat(document.getElementById('newVal').value);
var resultDiv = document.getElementById('changeResult');
if (isNaN(oldV) || isNaN(newV) || oldV === 0) {
resultDiv.style.display = 'block';
resultDiv.innerHTML = 'Please enter valid numbers. Original value cannot be zero.';
return;
}
var change = ((newV – oldV) / oldV) * 100;
var direction = change >= 0 ? 'Increase' : 'Decrease';
resultDiv.style.display = 'block';
resultDiv.innerHTML = direction + ': ' + Math.abs(change).toFixed(2) + '%Excel Formula: =(' + newV + '-' + oldV + ')/' + oldV + '';
}
function calculateModifier() {
var val = parseFloat(document.getElementById('baseVal').value);
var perc = parseFloat(document.getElementById('percAmount').value);
var resultDiv = document.getElementById('modifierResult');
if (isNaN(val) || isNaN(perc)) {
resultDiv.style.display = 'block';
resultDiv.innerHTML = 'Please enter valid numbers.';
return;
}
var decimalPerc = perc / 100;
var added = val * (1 + decimalPerc);
var subtracted = val * (1 – decimalPerc);
resultDiv.style.display = 'block';
resultDiv.innerHTML = 'If Increase: ' + added.toFixed(2) + ' If Decrease: ' + subtracted.toFixed(2) +
'Formula Increase: =' + val + '*(1+' + (perc/100) + ')' +
'Formula Decrease: =' + val + '*(1-' + (perc/100) + ')';
}