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Free Online Number Base Converter, Base 2 to Base 36

Convert a number between any two bases from 2 to 36, and see it in all thirty five at once. Whole numbers are handled at any size because the arithmetic uses big integers rather than the usual sixteen digit limit, and a fraction that cannot be written exactly in the new base is marked as cut off rather than quietly rounded.

Free Forever Nothing Uploaded Base 2 To Base 36 Any Size Of Number

Free Online Number Base Converter, Base 2 to Base 36

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🔢 Number Base Converter Base 2 to base 36 · any size of whole number · fractions marked when cut

The sum runs in your browser. Nothing you type is sent anywhere.

🔢 The number

Digits beyond nine are written as letters, so A is ten and Z is thirty five. Case does not matter, and a fractional part after a dot is fine.

The number

From base

To base

Fraction places

Common bases

Try one of these

The fourth is larger than an ordinary calculator can hold without losing digits, and the sixth never ends in binary.

In base 16

—

In decimal—

Digits in the answer—

Exact—

The same number written in all thirty five bases. The row you asked for is marked.

Base	The number

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How to Convert Between Number Bases

Three steps, and the third is where the detail is.

Type the number and say what base it is in Digits past nine are letters, so A is ten and F is fifteen. Case does not matter. A dot starts the fractional part.

Choose the base to convert to Anything from 2 to 36. The common ones have buttons, and the answer updates as you type rather than waiting for a convert button.

Check whether it came out exact Whole numbers always do. A fraction may not, because a fraction that ends in one base can run forever in another, and the page says which happened rather than rounding quietly.

What to Know About Number Bases

Digits, sizes and the fractions that never end.

Whole numbers are exact at any size. An ordinary calculator keeps about sixteen digits, and converting a longer number by the usual method silently drops the rest. Since the whole point of a base converter is the digits, that is a fatal flaw. This one uses big integer arithmetic, so a thirty digit number converts to hexadecimal and back and comes out exactly as it went in.

A fraction that ends in one base may not in another. A fraction ends only when its denominator divides a power of the base. A half is 0.5 in decimal and 0.1 in binary, both exact. A tenth is 0.1 in decimal and never ends in binary, because ten has a factor of five and two does not. So 0.1 in binary is 0.0001100110011 repeating forever, and the page marks it as cut off rather than presenting a rounded value as if it were the answer.

Letters are digits past nine. Base 16 needs sixteen symbols and there are only ten numerals, so A to F stand for ten to fifteen. The same idea runs to base 36, where Z is thirty five. Case is ignored, because a lowercase hex colour and an uppercase one are the same number.

Every base at once, because the next question is usually another base. Someone asking what a number looks like in octal usually wants hexadecimal a moment later. The full table from 2 to 36 is one click away rather than another conversion, and it also makes the pattern visible: the higher the base, the fewer digits.

The decimal value is always shown. Whatever you convert between, the decimal reading is given too, because it is the one everybody can check at a glance. It is a free sanity check on both the input and the output.

It runs in your browser with nothing uploaded. The arithmetic is in the page, so it works offline once loaded and nothing you type is sent anywhere.

Key Features & Capabilities

What it does, and what it deliberately does not.

Any base from 2 to 36 In either direction, with the common ones on buttons and the rest typed in.

No size limit on whole numbers Big integer arithmetic, so a thirty digit number survives a round trip exactly.

Cut fractions marked A fraction that cannot be written exactly in the new base is labelled rather than rounded quietly.

All thirty five bases at once One click shows the same number in every base from 2 to 36.

Letters and case handled A to Z for the digits past nine, in either case, as hex is written both ways in practice.

Nothing is uploaded It runs in this tab and keeps working offline.

About Number Bases

A base is how many different digits a number system uses before it has to add a place. Decimal uses ten, so after 9 comes 10. Binary uses two, so after 1 comes 10. The number itself does not change when you convert it; only the way it is written does. Eleven apples are eleven apples whether you write them as 11, as 1011, or as B.

Bases beyond ten need symbols for the extra digits, and the convention is to carry on with letters: A is ten, B is eleven, and so on up to Z for thirty five in base 36. That is why hexadecimal colour codes look like words, and why base 36 is used for short identifiers, since it packs the most information into each character using only digits and letters.

The place where converters most often go wrong is size. Ordinary floating point arithmetic keeps about sixteen significant digits, and the usual approach of parsing to a number and then formatting it silently loses everything past that. For a base converter this is fatal, because the digits are the entire point. This page does the arithmetic with big integers, so a whole number of any length converts and converts back exactly.

Fractions are the other difficulty, and here the honest answer is sometimes that there is no exact answer. A fraction terminates in a given base only when its denominator divides some power of that base. One half terminates in binary and in decimal. One tenth terminates in decimal and never in binary, because the denominator has a factor of five that two cannot supply. So a tenth written in binary runs on forever, and any converter that shows a tidy string of digits is showing you a rounded value. This one marks the answer as cut off when that happens, and lets you choose how many places to see.

Frequently Asked Questions

Bases, letters, fractions and very large numbers.

They are the digits past nine. A is ten, B is eleven, through to F for fifteen in hexadecimal and Z for thirty five in base 36. Case does not matter.

Yes, at any length. The arithmetic uses big integers rather than ordinary floating point, so nothing is lost past sixteen digits the way it is in most converters.

Because it does not end in the new base. A fraction terminates only when its denominator divides a power of that base. A tenth ends in decimal but runs forever in binary, so what you see is the start of an infinite expansion.

Short identifiers. With the ten digits and twenty six letters it packs more into each character than hexadecimal while staying typeable and case insensitive, which is why it appears in short links and reference codes.

Because sixteen is a power of two, so each hex digit is exactly four binary digits. That makes converting between hex and binary a matter of substitution rather than arithmetic, and it makes byte values two tidy characters instead of eight.

Yes. A leading minus sign is kept and applied to the result; the digits themselves are converted the same way either way.

No. The arithmetic runs in your browser, so nothing you type leaves the page and it works offline.