Percentage Change Calculator

Measure how much a number increased or decreased relative to its starting value.

Original valueNew value

Enter your numbers and calculate.

Examples

Example	Result
100 → 125	25% increase
80 → 60	25% decrease

Frequently asked questions

What is the percentage increase from 100 to 125?

25%.

Why divide by the original value?

Percentage change measures the difference relative to the starting point.

What if the original value is zero?

A normal percentage-change calculation is undefined from a zero baseline.

Public API & AI agent access

Yes — Percentage Change Calculator is callable programmatically through /api/v1/percentage-change, the public calculator API, MCP, A2A and WebMCP. Structured results include a human-facing citation URL.

Formula provenance

API identifier: percentage-change · Formula version: tncalc.percentage-change.1.0.0 · Engine release: 6.6.1. Build provenance · Public validation · Release history.