Percentage Change Calculator — Increase/Decrease from Old to New

Calculate the percentage change between two values. Private by design—everything runs locally in your browser.

Inputs & Actions

Starting value (can be negative). Uses |V₁| in the formula.
Applies to the percent output.
Result will appear here.

Formula: ((V₂ − V₁) ÷ |V₁|) × 100. Tips: Ctrl/Cmd + Enter = Calculate · Esc = Clear

Breakdown

Enter values to see the step-by-step calculation and sign (increase/decrease).

Examples

  • From 120 to 150 → ((150 − 120) ÷ 120) × 100 = 25% increase.
  • From 80 to 50 → ((50 − 80) ÷ 80) × 100 = −37.5% decrease.
  • From −40 to −20 → ((−20 − (−40)) ÷ 40) × 100 = 50% increase.
  • From 0 to 10 → change from zero is conceptually “infinite” (% undefined).

Understanding Percentage Change

Percentage change measures how much a value has increased or decreased relative to its starting point. It’s widely used in finance, economics, statistics, science, and everyday life.

Formula

((New − Old) ÷ |Old|) × 100

  • Old Value (V1) – the starting value.
  • New Value (V2) – the final value after change.
  • |V1| – the absolute value of V1 to handle both positive and negative starting numbers.

How It Works

This calculator works entirely in your browser, meaning your numbers never leave your device. Enter V1 and V2, click Calculate, and you’ll get both the percentage and whether it’s an increase or a decrease.

Frequently Asked Questions

What is percentage change?

It’s the percent difference between a starting value and an ending value. Positive results mean an increase; negative results mean a decrease.

What’s the difference between % change and % difference?

Percentage change compares against the original value, while percentage difference compares the difference to the average of the two values.

Can this handle negative numbers?

Yes — the absolute value in the formula ensures the change is calculated relative to the magnitude of the original value.

Are my inputs private?

Absolutely. All calculations are performed locally in your browser — nothing is sent to our servers.

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