Percentage Change Calculator: Find the % Increase or Decrease Between Two Numbers

Whether your sales went up, your weight went down, or a price on a receipt just doesn’t look right, this Percentage Change Calculator tells you exactly how much something moved — as a clean, easy-to-read percentage — in seconds.

What Is Percentage Change?

Percentage change measures how much a value has increased or decreased compared to its original value, expressed as a percentage. It’s the go-to way to compare two numbers — an old price and a new price, last year’s revenue and this year’s, a starting weight and a current weight — without needing to think in raw numbers.

If the result is positive, the value went up (a percentage increase). If it’s negative, the value went down (a percentage decrease). The calculator handles the sign automatically, so you always get a clear “increased by” or “decreased by” answer instead of just a raw number.

How to Use the Calculator

1. Enter the Old Value — the starting number (e.g., last month’s price, your original weight, last year’s traffic).
2. Enter the New Value — the number you’re comparing it to now.
3. Get your result instantly — the percentage increase or decrease, calculated and labeled automatically.

There’s no sign-up, no app to download, and no limit on how many times you can calculate — just plug in two numbers and read the answer.

Worked Examples

Example 1: Percentage Increase (Price Going Up)

A product’s price rises from $40 to $52. What’s the percentage increase?

Example 2: Percentage Decrease (Weight Loss)

Someone’s weight drops from 180 lbs to 162 lbs. What’s the percentage decrease?

Example 3: Percentage Decrease (Sales Drop)

Monthly sales fall from 2,500 units to 2,125 units. What’s the change?

Quick Reference Table

Percentage Change vs. Percentage Difference: What’s the Difference?

These two terms get mixed up constantly, but they answer different questions:

• Percentage change assumes one value is the “before” and the other is the “after.” It has a direction (increase or decrease) and always divides by the original value. This is what most people mean when comparing prices, scores, or measurements over time.
• Percentage difference is used when neither number is clearly the “original” — you’re just comparing two independent values (like two competitors’ prices, or two lab measurements). It divides by the average of the two numbers instead, and it’s always expressed as a positive value since there’s no “before” or “after.”

In practice: if you’re tracking how something changed over time, use percentage change. If you’re comparing two unrelated values side by side, percentage difference is the more accurate term — and this calculator’s core formula (based on an original vs. a new value) covers the vast majority of real-world “how much did this change” questions.

Common, Real-World Uses

• Shopping and discounts. Check whether a “sale” price really reflects the discount percentage advertised.
• Business and finance. Compare revenue, expenses, or growth between two periods (month-over-month, year-over-year).
• Health and fitness. Track percentage change in weight, body fat, or workout performance over time.
• Investing. Work out the percentage gain or loss on a stock, crypto, or fund between purchase and current price.
• Academics and grading. Compare test scores or grades between two attempts.
• Everyday math. Quickly settle questions like “how much more/less is this” without doing the arithmetic by hand.

Frequently Asked Questions

Whether you’re checking a discount, tracking your progress, or comparing this year’s numbers to last year’s, the Percentage Change Calculator gives you an accurate, clearly labeled answer in seconds — no manual math required.