A 50% drop needs 100% back
Fall from 100 to 50? You must double (100%) to return—percentage change is always relative to the starting point.
Base effect
Percentage Change Calculator — Increase/Decrease from Old to New
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.
5 Fun Facts about Percentage Change
Zero makes infinity
Any non-zero jump from 0 makes the percent change conceptually infinite, which is why the calculator flags it as undefined.
Math quirk
Compounding hides in plain sight
A steady 1% daily increase is +37.8x over a year (≈3,678%). Small changes stack explosively.
Everyday exponential
Negative starts still work
Using |Old| in the formula lets you compare changes from negative baselines—handy for net losses flipping to gains.
Handles negatives
Rounding can flip the story
A 0.49% dip rounds to 0% at one decimal, but a 0.51% rise rounds to +0.5%. Precision settings shape the headline.
Data storytelling