What is Percentage Increase Calculator?

The Percentage Increase Calculator is a free online tool that instantly computes percentage changes between two values. It supports both increases and decreases, displaying negative results in red. Users can enter any two of three fields (original value, new value, percentage change) and the third auto-calculates. Results update as you type, with step-by-step formula display and plain English explanations.

Who it's for

• Job seekers and employees — Compare salary offers, calculate raise percentages, or convert a dollar increase into a percentage for annual reviews.
• Shoppers and budgeters — Track price increases on groceries, rent, subscriptions, or any recurring expense to understand real cost changes.
• Investors and homeowners — Measure portfolio returns, stock growth, or property value appreciation in percentage terms for clearer financial comparisons.

Key features

Auto-calculation as you type

Results update instantly the moment you change a digit — no buttons to press, no waiting. The tool runs the formula ((New − Old) / Old) × 100% on every keystroke and displays each step so you can follow along or copy it into a report.

Three-field input for any missing value

Unlike most calculators that only go one direction, this tool lets you fill in any two of the three fields (original value, new value, percentage change) and solves for the missing one. Know the original and the percentage but not the new value? Enter those two and the calculator fills in the rest.

Decrease support with red display

When the new value is smaller than the original, the result comes back negative and the display switches to red. Going from 500 to 400 gives you −20%, meaning a 20% decrease. You don't need a separate percentage increase/decrease calculator — this one handles both directions automatically.

Value + Percent mode for quick calculations

A dedicated mode lets you start with a base value and apply a percentage increase or decrease directly. Perfect for scenarios like "What is $1,200 increased by 15%?" — the tool shows the new value and the step-by-step math.

What stands out

"Fill any two — the third auto-calculates."

This three-way flexibility sets the calculator apart from typical tools that only compute percentage from two values. Whether you need to find the original price before a markup, calculate the percentage change between two numbers, or determine the final value after a known increase, the tool adapts to your specific question without requiring you to rearrange formulas manually.

Worth checking out if…

You regularly deal with salary negotiations, price comparisons, investment tracking, or property valuations and want a single tool that handles increases, decreases, and reverse calculations without switching between different calculators.