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Percentage Change Calculator

Calculate percentage change, percentage of a value, original value.

⚠️ Not financial advice. Results are illustrative only and should not be used as the basis for any investment, tax, or financial decision. Consult a qualified financial adviser or chartered accountant before acting on any figure shown.

What is the % change from A to B?

Five ways to calculate with percentages

This calculator handles all common percentage questions in one place. Switch between five modes depending on what you are trying to find:

  • % Change: How much did something increase or decrease?
  • % Of: What percentage is B of A?
  • Find Value: What is X% of a number?
  • Reverse %: What was the original value before a percentage was applied?
  • % Difference: How different are two numbers, symmetrically?

Common everyday uses

  • Finance: Calculate stock price change, portfolio gain/loss, salary hike percentage.
  • Shopping: Find original price before discount, verify sale savings.
  • Taxes: Calculate GST on an invoice, find pre-tax price.
  • Science: Percentage error, experimental deviation, concentration changes.

Quick reference formulas

% Change = (New − Old) / |Old| × 100  |  % of: B/A × 100  |  X% of A: A × X/100  |  Reverse: B / (X/100)  |  % Diff: |A−B| / ((A+B)/2) × 100

Common use cases

Investors use percentage change to track portfolio gains or losses between two dates — for example, a stock moving from ₹150 to ₹195 is a 30% increase. Shoppers use the reverse percentage mode to find the original price before a discount: if a product is 25% off and now costs ₹750, the original was ₹1,000. Teachers and students use percentage difference when comparing two experimental measurements where neither is the definitive baseline. Finance teams use the percentage-of mode to calculate what share of total revenue each product line contributes.

GST calculation using percentages

In India, GST is applied as a percentage on the base price. To find the GST amount: GST = Base Price × (GST rate / 100). To find the pre-GST price from a GST-inclusive total: Base Price = Total / (1 + GST rate / 100). For example, if an item costs ₹1,180 inclusive of 18% GST, the base price is ₹1,180 / 1.18 = ₹1,000. Use the "Reverse %" mode in this calculator with the total as B and (100 + GST rate) as X to compute this instantly.

Frequently asked questions

How do I calculate percentage change?
Percentage change = ((New Value − Old Value) ÷ |Old Value|) × 100. A positive result is an increase, negative is a decrease. Example: from ₹80 to ₹100 is a 25% increase. From ₹100 to ₹80 is a 20% decrease (note: increase and decrease percentages are not symmetric).
What is the difference between percentage change and percentage difference?
Percentage change h direction — it measures change from a starting value to an ending value. Percentage difference is symmetric — it compares two values without implying one came before the other, using the average of both denominator: |A−B| ÷ ((A+B)/2) × 100. Use percentage difference when neither value is the 'baseline'.
How do I find the original price before a discount?
Use the 'Reverse %' mode. If an item is discounted by 20% and now costs ₹800, enter B=800 and X=80 (it is now 80% of the original). The calculator returns ₹1,000 original price. Alternatively: Original = Sale Price ÷ (1 − discount%).
Why is a 50% increase followed by a 50% decrease not back to the original?
Starting at 100: a 50% increase gives 150. A 50% decrease of 150 gives 75, not 100. This is because the second percentage is applied to a different base. Percentage changes are multiplicative, not additive. This is why 'X% increase then X% decrease' always results in a net loss.
What is compound percentage growth?
Compound growth applies a percentage repeatedly. If a stock grows 10% per year for 5 years, it is not 50% total — it is (1.10)^5 − 1 = 61.05%. Use the CAGR calculator for multi-year compound growth calculations.

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