Percent Change Calculator

What Is a Percent Change Calculator?

A percent change calculator determines how much a value has increased or decreased relative to its starting point, expressed as a percentage. The formula is ((New Value - Old Value) / |Old Value|) x 100. A positive result means growth; a negative result means decline. It is the standard way to compare values across different time periods or categories.

How to Use the Percent Change Calculator

1. Enter the original value: Type the initial or baseline number — last month's sales, your starting weight, the stock price at open.
2. Enter the new value: Type the current or updated number — this month's sales, your current weight, the stock price at close.
3. Read the result: The calculator shows the percent change instantly. Positive values indicate growth, negative values indicate decline.
4. Run additional comparisons: Adjust either input to compare different scenarios without reloading the page.

Who Is This For?

• Financial analysts tracking month-over-month or year-over-year performance metrics who need quick, accurate percentage calculations.
• Students working on statistics or economics homework who need to calculate relative change for assignments and practice problems.
• Fitness enthusiasts tracking body weight or performance changes over time who want to see their progress as a clear percentage.

Key Benefits

• 100% private — none of your numbers leave your device.
• Instant calculation — results update as you type, no waiting.
• Free forever — no paywall, no signup, no trial period.
• Works with any numbers — handles decimals, large values, and negative changes cleanly.

Common Use Cases

Monthly revenue tracking: Revenue went from $12,400 in January to $14,800 in February. Enter both to see 19.35% growth — useful for investor updates or internal reporting.

Weight loss progress: Starting weight was 195 lbs, current weight is 182 lbs. The calculator shows a 6.67% decrease — a more motivating metric than just pounds lost.

Academic grading: Your midterm score was 72 and your final was 88. That is a 22.22% improvement — useful for tracking study effectiveness across exams.

Frequently Asked Questions