Converters & Notation calculators

Conversion problems are about knowing the rule and applying it carefully: the right factor, the right base, the right symbol. Mistakes usually come from mixing unit types or reading remainders in the wrong order.

Each converter here shows the factor or method it used, so you can reproduce the answer by hand and learn the pattern.

All converters & notation tools

Scientific Notation Converter

Decimal to a × 10ⁿ and back.

Roman Numeral Converter

Numbers ↔ Roman numerals, with the breakdown.

Number Base Converter

Binary, octal, decimal, hex and bases up to 36.

Unit Converter

Length, mass, volume and temperature.

What you can do here

Convert length, mass, volume and temperature units
Convert between binary, octal, decimal and hexadecimal
Convert numbers to and from Roman numerals
Write very large or small numbers in scientific notation

Learn the method first

Guides in this category teach the idea, then hand you to the matching calculator to practise.

Scientific Notation: How to Write and Convert Numbers

Questions about this category

Are the conversion factors exact?

The inch, mile, pound and US volume units are defined exactly in terms of metric units, so the factors used are exact; results are shown to a stated number of decimals.