Percentage Change Calculator

Calculate percentage increase, decrease, and 4 other percent operations instantly.

Free Tool

How to use Percentage Change Calculator

Percentages appear everywhere — discounts, grade changes, financial returns, statistics — and our Percentage Change Calculator solves all six common percentage problems from one clean interface. Select your calculation mode from the tab grid: • Percentage Change — given an original and new value, calculates the percentage increase or decrease. Shows both the percentage and the absolute change. • New Value — given an original value and a percentage change, finds what the new value becomes. Handles both positive (increases) and negative (decreases) percentages. • Original Value — works backward: given the final value after a percentage change, finds the original starting value. Useful for reversing a markup or discount. • Percentage of a Number — finds what X percent of Y is. The classic "what is 15% of $80?" type calculation. • X is What Percent of Y? — given two numbers, calculates what percentage the first is of the second. Use this for grades (you scored 47 out of 60 — what percent is that?), market share, and proportions. • Compound Percentage — applies a percentage change repeatedly over N periods. Essential for understanding compounding discounts, multi-year price changes, or interest without a calculator formula. Quick presets for common discount and increase percentages appear when relevant — click any preset to pre-fill the percentage field instantly. All calculations display results to 4 decimal places for precision. The color coding helps at a glance: green for increases, red for decreases. A recent calculations history at the bottom tracks your last 5 calculations so you can refer back or compare related figures without re-entering them. Practical examples: calculate a 20% discount on a $149 item, find the original price before a 15% markup was applied, determine what percentage your savings account grew this year, or calculate compound annual growth across 5 years.

Frequently Asked Questions

What is the formula for percentage change?

Percentage change = ((New Value − Original Value) ÷ |Original Value|) × 100. The absolute value in the denominator ensures the sign of the result correctly indicates increase (positive) or decrease (negative) even when the original value is negative.

What is the difference between percentage change and percentage difference?

Percentage change has a direction — it compares a new value to an old one (before vs after). Percentage difference is symmetric — it compares two values without implying one comes first, using the average of both as the denominator. Use change for before-after comparisons, difference for comparing two independent values.

How do I calculate the original price before a discount?

Use the "Original Value" mode. Enter the discounted price and the percentage discount. The calculator divides: original = discounted price ÷ (1 − discount%). For example, a $68 item after a 15% discount had an original price of $68 ÷ 0.85 = $80.

What is compound percentage and when do I use it?

Compound percentage applies a rate multiple times, with each application based on the new value. A price that increases 10% per year doesn't grow linearly — after 3 years at 10% compound: $100 → $133.10, not $130. Use compound percentage for investment returns, inflation, and any scenario where the base changes each period.

Why does adding 20% and then removing 20% not return to the original number?

Because the base changes. Adding 20% to $100 gives $120. Removing 20% of $120 is $24, leaving $96 — not $100. This is a common mental math error. The "Compound Percentage" mode can demonstrate this: enter $100, +20%, 1 period to see $120, then −20%, 1 period to see $96.

Recommended