Convertworld: A free converter to convert all units

Last updated on 25 May 2026

You prepare a chapter on measurements in mathematics or science. Looking for a simple way to show your students the difference between a mile and a kilometer, between a gallon and a liter, between Fahrenheit degrees and Celsius degrees. You want something that is immediately usable, without registration, installation or subscription. Something you can project in class or share as a complementary resource.

Have you ever been in circles on Google looking for a simple converter, only to end up on a site full of dubious ads that doesn’t even answer your question?

In short, you may need Convertworld.

Convertworld, a universal and free unit converter

Convertworld is an online unit conversion service, available free of charge since 2005. On paper, nothing revolutionary: it is a converter. But in use, it is one of the most comprehensive I have seen for educational use.

The site covers an impressive spectrum: lengths, masses, volumes, temperatures, speeds, areas, currencies, shoe sizes, paper sizes, time zones, radioactivity, photometry, electrical quantities, and even a BMI calculator or pregnancy schedule. Everything is available in more than thirty languages, with exchange rates updated in real time.

It is not an AI tool. It is not a sophisticated application. It is a solid, stable web tool that does exactly what it has promised for 20 years. And sometimes that’s exactly what you need in class.

What does Convertworld offer for the class?

Conversions for almost all school disciplines

The menu of the site is organized by thematic families. A few telling examples for a classroom:

Mathematics and physics:

• Length (meters, feet, inches, miles, light years).
• Mass (kilos, pounds, ounces, tons).
• Volume (litres, gallons, pints, centilitres).
• Area (m², hectares, acres).
• Pressure, speed, acceleration, force, angle.

In chemistry:

• Molar mass, density, dynamic and kinematic viscosity, quantity of matter.

In geography:

• Time zones (for contextualize a map, explain jet lag).
• Currencies (real-time exchange rate for more than 150 currencies, including Bitcoin).

In technology and computer science:

• Computer measurements (bits, bytes, kilobytes, megabytes).
• Bandwidth.

Physical education and health:

• BMI (body mass index).
• Clothing and shoe sizes to compare the European, American, British and Asian systems.

It is this diversity that makes Convertworld useful far beyond just Mathematics Course.

A currency converter updated in real time

This is one of the most useful sections for courses in economics, geography or even Modern languages. Convertworld displays discounted exchange rates for more than 150 currencies, from the US dollar to the Malagasy ariary to bitcoin.

In seconds, you can show your students how much one euro in Japanese yen is worth today, or compare the purchasing power of different currencies. A good entry point for a discussion on financial markets or global inequalities.

A multilingual tool, without account or installation

No account creation. No e-mail address to be provided. No application to download. We arrive at the site, we convert, we leave. The interface is available in more than 30 languages, which may be of interest to teachers who work with allophone students or who want to compare interfaces in different languages.

The interface is sober. Maybe a little dated visually, but clear and functional. And this, for classroom use, is often better than an overloaded interface.

How to use Convertworld in class?

In math, to give meaning to units

Instead of teaching conversions in an abstract way, project Convertworld to the table. Show live how much 5 miles in miles, or how much a pound weighs in grams. Enter the values, observe the result in real time, and let students propose their own conversions. The tool becomes a simple visual manipulation medium.

Physical Sciences and Chemistry

Conversions of energy (joules, calories, kilowatt hours), pressure (pascals, bars, atmospheres) or density are often confusing. Having a reliable reference tool at the click of a button can help consolidate learning and verify calculations.

Geography and SVT

Time zones make it possible to concretely visualize the discrepancies between countries. The section on wind speed can complete a course on meteorological phenomena. Area can be used to compare countries, regions or ecosystems.

In the course of modern languages

In English, showing that Americans or Brits still use miles, yards, thumbs and gallons helps students better understand English culture. The same applies to temperatures: 72°F, what does it mean concretely for a French student?

Strengths

• Free, no account, no installation. Zero friction to begin with.
• Very wide coverage. Few tools offer so many categories in one piece.
• Real-time exchange rate. Useful for teachers dealing with economics or geography.
• Multilingual. Accessible to a variety of audiences.
• Stable. The site has existed since 2005, a real guarantee of reliability.
• No student account to manage. No personal data collected for common use. The site states that it complies with the GDPR, which is a positive point for use in school contexts.

I like … less

Convertworld is funded by advertising. This is the price to pay for free. The ads are present, sometimes invasive depending on the screens. It is not prohibitive in class if you go through a projector, but it can be a barrier for autonomous use by students on their own device.

The interface has not changed much visually in recent years. It remains functional, but lacks a bit of elegance compared to newer tools.

Finally, some very specialized sections (radioactivity, kinematic viscosity) will not necessarily find a taker in an ordinary classroom. But they're there if you need them.

To remember

Convertworld is the digital tool you are not looking for but should have in your favourites. Not because it is new, not because it uses AI, not because it offers a revolutionary learning experience. But because it does exactly what it says, does it well, is free and covers a pedagogical territory often poorly served by the tools available.

If you teach science, math, geography, economics or modern languages, if you provide academic support or even for personal use, Convertworld clearly deserves a bookmark in your browser.

To be tested during your next course on units of measurement. You'll see.

---

Convertworld is available for free on convertworld.com. No registration is required. Interface available in French and more than thirty languages.