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Percentage calculator — two calculations, one page

The two percentage calculations people need most often, on one page: what percent a part is of a total, and what a percentage of a number is. Every calculation stays in the history below, so you don't have to redo it if you need it again.

▶ Use this app

percentagecalculatormathonline calculator

What it records

  • Part (e.g. 45)
  • Total (e.g. 200)
  • Percentage (e.g. 20)
  • Of (e.g. 150)

How it works

This is a Reactive app: a plain text document that your browser turns into a working app — forms, live data, tables, statistics and even charts, with nothing to install or configure.

  1. Use it right away. Hit “Use this app”: it opens right in your browser, ready to go, with data saved only on your device.
  2. Your data stays yours. Everything is stored locally on your device, kept separate for each app: no account, no server, nothing to set up.
  3. Make it your own. The text below is the entire app: copy it, tweak fields, views and words, and your changes become interactive instantly.
  4. Share it as a file. An app is a simple file: save it, export it or share it with a link; and with encrypted collaboration several people edit the same data in real time.
The app’s source
# 🧮 Percentage calculator

The two percentage calculations people need most often, on one page: what
percent a part is of a total, and what a percentage of a number is. Every
calculation stays in the history below, so you don't have to redo it if you
need it again.

## What percentage is a part of a total?

::::form{path="calcsA" id="fpa"}
::input{form="fpa" field="part" type="number" placeholder="Part (e.g. 45)" required="true"}
::input{form="fpa" field="total" type="number" placeholder="Total (e.g. 200)" required="true"}
::add-form{form="fpa" path="calcsA" label="Calculate percentage"}
::::

:::table{path="calcsA" headers="Part,Total,Percentage" deletable="true" editform="fpa"}
{part} | {total} | {part/total*100}%
:::

## What is X% of a number?

::::form{path="calcsB" id="fpb"}
::input{form="fpb" field="percent" type="number" placeholder="Percentage (e.g. 20)" required="true"}
::input{form="fpb" field="total2" type="number" placeholder="Of (e.g. 150)" required="true"}
::add-form{form="fpb" path="calcsB" label="Calculate value"}
::::

:::table{path="calcsB" headers="Percentage,Total,Value" deletable="true" editform="fpb"}
{percent}% | {total2} | {percent*total2/100}
:::

Useful for a discount, a raise, a commission, or just to double-check a
mental estimate: type the numbers, get the result instantly, and keep it
around to compare with the next calculation.