About OnCalc

OnCalc is a free collection of online calculators that work right in your browser, with no download or sign-up.

What we offer

Alongside the scientific and basic calculators, we offer everyday tools such as date, unit and percentage calculators, and math and engineering tools such as base conversion, statistics, complex numbers, equations, calculus and matrices.

The calculators are available in Korean, English, Spanish, French, Portuguese, Arabic and Japanese; only the Korean lunar–solar calendar converter is offered in Korean alone.

Our principles

Free to use, with no sign-up.
Everything you enter is calculated in your browser and never sent to a server.
We follow published standards: the Korean lunar calendar follows the Korea Astronomy and Space Science Institute, and physical constants use CODATA values.
Calculation rules are checked with automated tests before they go live.

Found a mistake?

If a result looks wrong or an explanation is incorrect, please tell us at contact@oncalc.org. We will check it and fix it.