Why use BigInt instead of regular Number?

JavaScript's Number type is an IEEE-754 double, which can only represent integers exactly up to 2^53 − 1 (about 9.007 quadrillion). Beyond that, conversions silently lose precision: for example, 0xFFFFFFFFFFFFFFFF (a 64-bit unsigned max) rounds to a wrong decimal if you parse it with parseInt. This tool stores every value as a BigInt, so a 256-bit cryptographic hash or a 64-bit register dump converts byte-for-byte exact regardless of size.

How are negative numbers represented in binary (two's complement)?

When you enable a fixed bit width (8/16/32/64), the binary view shows the two's-complement representation. The rule is simple: to encode -n, take the unsigned binary of n, flip every bit, then add 1. So -1 in 8-bit becomes 11111111, and -128 becomes 10000000. The decimal field shows the signed integer, while the binary/hex fields show the raw fixed-width bit pattern. Without a fixed width, negatives are shown with a leading minus sign instead.

What's the difference between unsigned and signed?

For the same bit pattern, unsigned interprets the top bit as a regular value bit while signed interprets it as a sign bit. In 8-bit, 11111111 is 255 unsigned but -1 signed. This tool defaults to unsigned arithmetic for clarity but applies signed semantics whenever you type a negative decimal or use the NOT operator with a fixed bit width.

Why does my hex value sometimes have an "n" suffix when I copy it?

Pure BigInt literals in JavaScript end with the letter n (e.g. 255n). When you copy from this tool we strip that suffix and return the conventional 0x prefix (0xff) so the value pastes cleanly into any language — C, Python, Rust, Go, or another JS file. If you ever see a stray "n", it came from somewhere else.

Can I convert fractional or floating-point numbers?

No, this tool is for integers only. Fractional binary or hex (like 0.1 in binary) is a separate problem governed by IEEE-754 encoding rules. For decoding the bit layout of a 32- or 64-bit float, use our dedicated floating-point converter — it shows you the sign, exponent, and mantissa fields side-by-side with the decimal value.

Verifying a 64-bit register dump from a debugger

You paste 0xDEADBEEFCAFEBABE from a GDB session and need its unsigned decimal to compare against a spec value. parseInt would round it wrong above 2^53, so you drop it into the hex field here and read 16045690984833335486 exact, plus the full 64-bit binary to check which flag bits are set.

Setting a subnet mask while reading an RFC

The doc lists a mask as /26 but your router config wants it in hex. You type 255.255.255.192's last octet, 192, see 11000000 in 8-bit binary, and confirm the top two bits are the host-network split. Switching the bit width to 32 lets you build the whole 0xFFFFFFC0 mask in one view.

Teaching two's complement to a CS class

You want students to see that -1 in 8-bit is 11111111 and -128 is 10000000. You set the width to 8, type -1, then -128, and the binary field updates live so the class watches the sign bit flip. The same value shown in decimal, hex, and binary at once makes the encoding click without a whiteboard.

Packing color or flag constants for embedded code

Your firmware needs 0x1F as the low five bits of a status byte. You enter 31, read 00011111 in 8-bit, then OR it with 0x80 using the bitwise panel to set the high enable bit, landing on 0x9F. You copy 0x9f straight into the C header without retyping or guessing the math.

Number Base Converter

Number base converter — binary, octal, decimal, hex, and any base 2-36. Bitwise too.

Runs locally
Category Calculator
Best for Getting a realistic range before a purchase, plan, workout, or schedule decision.

Bases

Bit width:

Binary (0/1)

Decimal (-/0-9)

Hex (0-9 a-f)

Octal (0-7)

Presets:

Custom base

From baseInputTo base

Result:

3530

Bitwise operations

A (0x / 0b / dec)OperatorB (0x / 0b / dec)

dec8

hex0x8

bin0b1000

All math runs on BigInt — exact up to thousands of digits. Values stay in your browser.

What this tool does

A precise, BigInt-powered number base converter that handles binary, octal, decimal, hexadecimal, and any custom radix from 2 to 36. The four primary fields are live-linked: edit one and the other three update instantly with validation, so you always see the same value in every base. Built-in bitwise calculator covers AND, OR, XOR, NOT, left shift, and right shift across 8/16/32/64-bit widths, with proper two's-complement padding for the binary view. Because every value is stored as a BigInt, conversions are exact up to thousands of digits — no silent precision loss above 2^53 like naive Number-based converters. One-click copy on every base, quick presets for common constants (255, 1024, 65535, 2^31), and full client-side execution mean your data never leaves the browser.

Tool details

Input: Text + Numbers; The page exposes text boxes, numeric controls, file pickers, or structured inputs depending on the tool.
Output: Live result + Copy; The result area focuses on usable output, with copy, download, or preview actions when supported.
Privacy: Browser-side processing; The main tool logic does not call an external API, so inputs normally stay in the current tab.
Save / share: No account required; Open the page and use it; whether results survive refresh depends on the tool.
Performance budget: Initial JS <= 14 KB; No WASM budget is declared, keeping the tool quick to open on mobile.
Best fit: Calculator · Student; Category and role tags drive related tools, internal links, and quick fit checks.

How to use

1. Input

Paste or drop your content into the tool panel.
2. Process

Click the button. All processing is local in your browser.
3. Copy / Download

Copy the result or download to disk in one click.

How Number Base Converter fits into your work

Use it for fast estimates, comparisons, and planning numbers before you make the final call.

Calculation jobs

Getting a realistic range before a purchase, plan, workout, or schedule decision.
Comparing scenarios by changing one input at a time.
Turning rough assumptions into a number you can discuss.

Calculation checks

Double-check units, dates, rates, and rounding assumptions.
Treat health, finance, tax, and legal outputs as planning aids, not professional advice.
Save the inputs that produced an important result so you can reproduce it later.

Good next steps

These links move the current task into a more complete workflow.

Real-world use cases

Verifying a 64-bit register dump from a debugger
You paste 0xDEADBEEFCAFEBABE from a GDB session and need its unsigned decimal to compare against a spec value. parseInt would round it wrong above 2^53, so you drop it into the hex field here and read 16045690984833335486 exact, plus the full 64-bit binary to check which flag bits are set.
Setting a subnet mask while reading an RFC
The doc lists a mask as /26 but your router config wants it in hex. You type 255.255.255.192's last octet, 192, see 11000000 in 8-bit binary, and confirm the top two bits are the host-network split. Switching the bit width to 32 lets you build the whole 0xFFFFFFC0 mask in one view.
Teaching two's complement to a CS class
You want students to see that -1 in 8-bit is 11111111 and -128 is 10000000. You set the width to 8, type -1, then -128, and the binary field updates live so the class watches the sign bit flip. The same value shown in decimal, hex, and binary at once makes the encoding click without a whiteboard.
Packing color or flag constants for embedded code
Your firmware needs 0x1F as the low five bits of a status byte. You enter 31, read 00011111 in 8-bit, then OR it with 0x80 using the bitwise panel to set the high enable bit, landing on 0x9F. You copy 0x9f straight into the C header without retyping or guessing the math.

Common pitfalls

Forgetting to set a bit width before typing a negative number — without a width, -5 just shows as "-101" binary, not the 11111011 two's-complement byte you probably want.
Pasting a hex value with a stray "0x" or "h" suffix into the decimal field instead of the hex field; type 0xFF into the hex box, or just FF, never into the decimal box where it reads as zero.
Assuming a value above 2^53 is safe to round-trip through a spreadsheet first; copy 0xFFFFFFFFFFFFFFFF straight into this tool, because Excel and parseInt both corrupt it to 18446744073709552000.

Privacy

Every conversion and bitwise operation runs entirely in your browser with no network request, so a register dump, key fragment, or any hex value you paste never leaves your machine. The value you type is reflected into the URL only when you use the share link, so a sensitive number stays out of your history unless you deliberately copy that link.

FAQ

Tool combos

Folks in your role tend to reach for these alongside this tool.

Browse all tools for this role

Number Base Converter

Custom base

Bitwise operations

What this tool does

Tool details

How to use

1. Input

2. Process

3. Copy / Download

How Number Base Converter fits into your work

Calculation jobs

Calculation checks

Good next steps

Real-world use cases

Verifying a 64-bit register dump from a debugger

Setting a subnet mask while reading an RFC

Teaching two's complement to a CS class

Packing color or flag constants for embedded code

Common pitfalls

Privacy

FAQ

Roman Numeral Converter

Text to Binary Converter

Unit Converter

CSS Formatter & Minifier

Color Converter

PX REM EM Converter

Linux Permission (chmod) Calculator

Unix Timestamp Converter

IELTS Band Calculator

24-Point Solver & Game

555 Timer Calculator

A1C to Blood Glucose Calculator