Number Converter — Binary, Decimal, Hex, Octal, Roman, Words & Scientific
Convert a number between binary, decimal, octal, hexadecimal, Roman numerals, English words and scientific notation — all at once, live in your browser. Type in any format and copy any representation, with the step-by-step working shown.
How to Use
- Choose what format you are typing in (decimal, binary, hex, octal, Roman, words or scientific).
- Enter your number — every other representation updates instantly.
- Click any value (or its Copy button) to copy it.
- Open “Show work” to see the positional expansion and repeated-division steps.
One converter for every number system
This tool replaces a pile of one-way converters with a single page: type a value in any format and read it back in every other. It covers decimal (base 10, the everyday system), binary (base 2, how computers store everything), octal (base 8, still used for Unix file permissions), hexadecimal (base 16, the programmer’s shorthand for binary used in colour codes and memory addresses), Roman numerals, plain English words, and scientific notation. Everything runs in your browser — nothing is uploaded — and the “Show work” panel spells out the arithmetic so you can learn the method, not just copy the answer.
How the conversions work
From another base to decimal uses positional expansion: each digit is multiplied by its base raised to the column number and the products are added. For binary, 101010₂ = 1·2⁵ + 0·2⁴ + 1·2³ + 0·2² + 1·2¹ + 0·2⁰ = 42. From decimal to another base uses repeated division: divide by the base, keep the remainder, repeat, and read the remainders bottom-to-top. Roman numerals are built by subtracting the largest available value repeatedly (so 1984 → M, CM, L, X, X, X, IV → MCMLXXXIV) and read back by adding each symbol, subtracting any smaller value that sits before a larger one. Scientific notation shifts the decimal point so a single non-zero digit sits to its left, times a power of ten.
Quick reference
About the Number Converter — Binary, Decimal, Hex, Octal, Roman, Words & Scientific
The Number Converter — Binary, Decimal, Hex, Octal, Roman, Words & Scientific is a simple, free helper for everyday tasks that runs entirely on your own device. Convert a number between binary, decimal, octal, hexadecimal, Roman numerals, English words and scientific notation — all at once, live in your browser. Type in any format and copy any representation, with the step-by-step working shown.
How it works
Enter a number and choose your units — the converted value shows instantly. Everything runs locally, so nothing you type leaves your device. Double-check the direction of the conversion and you are set.
Want the deeper story? The Knowledge Base explains the ideas behind the tools in more detail.
Frequently Asked Questions
Which conversions does this cover?
Every pairing between decimal, binary (base 2), octal (base 8), hexadecimal (base 16), Roman numerals, English words, and scientific notation. Because all formats are shown at once, one page replaces dozens of one-way converters — type in any format and read off all the others.
How do I convert decimal to binary by hand?
Divide the number by 2 repeatedly and write down the remainder each time; reading the remainders from bottom to top gives the binary digits. For example 42 → 21 r0, 10 r1, 5 r0, 2 r1, 1 r0, 0 r1 → 101010. The “Show work” panel does exactly this for binary, octal and hex.
How do I read hexadecimal?
Hex uses digits 0–9 then A–F for 10–15, and each hex digit is exactly four binary bits. To get decimal, multiply each digit by a power of 16: 2A = 2×16 + 10 = 42.
What are the limits?
Roman numerals only exist for 1–3999 (there is no zero or negative). English words go up to the trillions. Binary/octal/hex/decimal handle the full range of standard numbers; very large values are shown in scientific notation too.
Is anything uploaded?
No. The whole conversion runs in your browser with JavaScript — nothing is sent to a server.
How do I use the Number Converter — Binary, Decimal, Hex, Octal, Roman, Words & Scientific?
Simply type or paste your value and read the result, which refreshes the instant you change something. There is nothing to submit and nothing to wait for.
Does it cost anything or need an account?
No. The tool is completely free, there is no account to create, and it keeps working offline after the page first loads.
Is anything I type uploaded?
No. The tool works entirely on your device, so the values you enter never leave your browser.
Common Use Cases
Programming & debugging
Flip a value between decimal, hex and binary when reading memory dumps, colour codes, bitmasks or register values.
Learning number systems
See the same number in every base side by side, with the positional-value and division working spelled out.
Unix permissions
Convert octal permission bits (755, 644) to and from binary and decimal.
Roman numerals
Turn a year or chapter number into Roman numerals (or back) — clock faces, copyright dates, outlines.
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