# Percentage Calculator Guide

Work out percentages, increases and decreases.

- Tool: https://ilham.dev/tools/percentage-calculator/
- Guide URL: https://ilham.dev/guides/percentage-calculator/
- Tool guides index: https://ilham.dev/guides/tools/
- Broader guide: Dates, Timestamps, and Time Zones (https://ilham.dev/guides/dates-times-and-time-zones/)

## What it does

Work out percentages in the forms that actually come up: what X% of Y is, what percentage X is of Y, and the increase or decrease between two values.

## Use the tool

Open https://ilham.dev/tools/percentage-calculator/, add the input the tool asks for, run it, and check the output before using it elsewhere.

## Input and output

- Input: text.
- Output: text.
- Category: Math.

## Privacy and processing
Processing happens locally in your browser. This tool does not upload the input to ilham.dev.

## Questions

### Why do a percentage rise and fall not cancel out?

Because they are relative to different bases. A 50% rise followed by a 50% fall leaves you at 75% of where you started, not back at the beginning.