Int64 Exactly 64 Bits 8 Bytes Two’s Complement Exact BigInt
Signed 64-Bit Integer Decoder

Hex Int64 to Binary Converter

Convert a raw hexadecimal 64-bit pattern to exact binary and decode its signed Int64 value. Values from 0000000000000000–7FFFFFFFFFFFFFFF are non-negative, while 8000000000000000–FFFFFFFFFFFFFFFF represent negative values using two’s complement.

Signed Int64 decoding 64 exact bits No Number precision loss Sign bit detection
Hex → Int64 Binary
● LIVE
Raw hex 0000000000000000–FFFFFFFFFFFFFFFF · optional 0x · sign comes from bit 63
INT64 BINARY SIGNED 64-BIT
1111111111111111111111111111111111111111111111111111111111111111
Hex: FFFFFFFFFFFFFFFF Sign bit: 1 Storage: 8 bytes
Signed decimal: -1
INT64 INTERPRETATION If bit 63 = 1, signed value = unsigned − 2⁶⁴
FFFFFFFFFFFFFFFF → 64 ones · unsigned 18446744073709551615 · signed -1
TRY:
Data Type Int64
Width 64 bits / 8 bytes
Positive Half 0000…–7FFF…
Negative Half 8000…–FFFF…
Encoding Two’s complement

Hex Int64 to Binary Converter

The Hex Int64 to Binary Converter converts a hexadecimal 64-bit pattern into exactly sixty-four binary digits and interprets that pattern using signed Int64 two’s-complement rules.

The lower half of the pattern space represents zero and positive values. The upper half represents negative values from -9,223,372,036,854,775,808 through -1.

Example: FFFFFFFFFFFFFFFF converts to 64 binary ones and represents Int64 -1.

What Is Int64?

Int64 is a signed integer stored in exactly sixty-four bits or eight bytes. Standard Int64 values use two’s-complement representation.

Width: 64 bits Storage: 8 bytes Minimum: 8000000000000000 = -9223372036854775808 Maximum: 7FFFFFFFFFFFFFFF = 9223372036854775807

Hex Int64 Range

All sixteen-digit hexadecimal patterns can represent raw 64-bit data. Their signed meaning depends on bit 63.

Hex Range Sign Bit Int64 Meaning
0000000000000000–7FFFFFFFFFFFFFFF 0 0 to 9223372036854775807
8000000000000000–FFFFFFFFFFFFFFFF 1 -9223372036854775808 to -1

How to Convert Hex Int64 to Binary

Each of the sixteen hexadecimal digits maps directly to four binary bits. Once the 64-bit pattern is constructed, bit 63 determines whether signed two’s-complement decoding is required.

FFFFFFFFFFFFFFFE → 1111111111111111111111111111111111111111111111111111111111111110 Unsigned pattern: 18446744073709551614 Signed Int64: 18446744073709551614 − 18446744073709551616 = -2

Hex Int64 Conversion Examples

Hex Binary Int64 Decimal
0000000000000000 0000000000000000000000000000000000000000000000000000000000000000 0
0000000000000001 0000000000000000000000000000000000000000000000000000000000000001 1
00000000FFFFFFFF 0000000000000000000000000000000011111111111111111111111111111111 4294967295
7FFFFFFFFFFFFFFF 0111111111111111111111111111111111111111111111111111111111111111 9223372036854775807
8000000000000000 1000000000000000000000000000000000000000000000000000000000000000 -9223372036854775808
8000000000000001 1000000000000000000000000000000000000000000000000000000000000001 -9223372036854775807
FFFFFFFFFFFFFFFD 1111111111111111111111111111111111111111111111111111111111111101 -3
FFFFFFFFFFFFFFFE 1111111111111111111111111111111111111111111111111111111111111110 -2
FFFFFFFFFFFFFFFF 1111111111111111111111111111111111111111111111111111111111111111 -1

Example: FFFFFFFFFFFFFFFF as Int64

FFFFFFFFFFFFFFFF Unsigned: 18446744073709551615 Signed: 18446744073709551615 − 18446744073709551616 = -1

Example: 8000000000000000 as Int64

8000000000000000 → 1000000000000000000000000000000000000000000000000000000000000000 Unsigned: 9223372036854775808 Signed: 9223372036854775808 − 18446744073709551616 = -9223372036854775808

This is the minimum signed Int64 value.

Example: 7FFFFFFFFFFFFFFF as Int64

7FFFFFFFFFFFFFFF → 0111111111111111111111111111111111111111111111111111111111111111 = 9223372036854775807

This is the maximum positive Int64 value.

Int64 Two’s-Complement Formula

Let U be the unsigned value of the raw 64-bit pattern.

If U < 2⁶³: Int64 = U If U ≥ 2⁶³: Int64 = U − 2⁶⁴

Numerically, the boundaries are 9,223,372,036,854,775,808 for 2⁶³ and 18,446,744,073,709,551,616 for 2⁶⁴.

Int64 vs UInt64

The raw binary pattern does not change between UInt64 and Int64. Only the numerical interpretation changes when the highest bit is one.

Hex UInt64 Int64
7FFFFFFFFFFFFFFF 9223372036854775807 9223372036854775807
8000000000000000 9223372036854775808 -9223372036854775808
FFFFFFFFFFFFFFFE 18446744073709551614 -2
FFFFFFFFFFFFFFFF 18446744073709551615 -1

Why BigInt Is Necessary for Int64

The Int64 range extends far beyond JavaScript’s maximum safe integer for ordinary Number values. Using floating-point Number conversion can round large integers and produce incorrect signed decoding.

Number.MAX_SAFE_INTEGER = 9007199254740991 Int64 maximum = 9223372036854775807

This calculator therefore keeps the numerical calculation in BigInt and builds the binary result directly from hexadecimal nibbles.

Why the Output Always Has 64 Bits

Int64 is fixed-width, so all results contain exactly sixty-four binary digits regardless of how small the entered value is.

Input Normalized Hex Output Width
1 0000000000000001 64 bits
FF 00000000000000FF 64 bits
FFFFFFFF 00000000FFFFFFFF 64 bits
FFFFFFFFFFFFFFFF FFFFFFFFFFFFFFFF 64 bits

Why Int64 Uses Raw Hex Without a Minus Sign

Negative Int64 values are already encoded within their two’s-complement 64-bit patterns.

-1 → FFFFFFFFFFFFFFFF -2 → FFFFFFFFFFFFFFFE minimum Int64 → 8000000000000000

The calculator therefore expects raw hexadecimal patterns rather than an external minus sign.

Optional 0x Prefix

One optional 0x or 0X hexadecimal prefix is accepted.

0xFFFFFFFFFFFFFFFE → FFFFFFFFFFFFFFFE → Int64 -2

Why 10000000000000000 Is Invalid

A raw Int64 pattern contains exactly sixty-four bits. Hexadecimal 10000000000000000 represents 2⁶⁴ and requires sixty-five bits.

FFFFFFFFFFFFFFFF = 64 bits 10000000000000000 = 65 bits Does not fit in Int64

Does Endianness Change Int64 Conversion?

Endianness matters when the eight constituent bytes are stored or transmitted. This calculator does not reorder those bytes; it interprets the hexadecimal value exactly as written.

Input: 123456789ABCDEF0 Bytes preserved as: 12 34 56 78 9A BC DE F0

Common Uses for Int64 Values

  • Signed 64-bit application integers.
  • Large signed counters.
  • Database integer fields.
  • 64-bit processor registers.
  • Signed file offsets and timestamps where applicable.
  • Binary protocol fields.
  • Firmware and embedded-system debugging.
  • Reverse engineering raw binary data.
  • Large signed measurements.
  • Two’s-complement programming analysis.

Common Hex Int64 Conversion Mistakes

  • Reading FFFFFFFFFFFFFFFF as UInt64 maximum instead of Int64 -1.
  • Reading 8000000000000000 as positive 9,223,372,036,854,775,808.
  • Using JavaScript Number for large 64-bit integers.
  • Adding an external minus sign to an already encoded raw pattern.
  • Using UInt64 interpretation for a signed field.
  • Trying to fit a 17-digit significant hex value into Int64.
  • Automatically reversing byte order.
  • Confusing binary representation with signed decimal meaning.

Hex Int64 to Binary Converter FAQs

What is Int64?
Int64 is a signed 64-bit integer type with values from -9,223,372,036,854,775,808 through 9,223,372,036,854,775,807.
What is FFFFFFFFFFFFFFFF as Int64?
It converts to 64 binary ones and represents signed Int64 -1.
What is FFFFFFFFFFFFFFFE as Int64?
It represents signed Int64 -2.
What is 8000000000000000 as Int64?
It represents the minimum Int64 value, -9,223,372,036,854,775,808.
What is 7FFFFFFFFFFFFFFF as Int64?
It represents the maximum positive Int64 value, 9,223,372,036,854,775,807.
Why does FFFFFFFFFFFFFFFF equal -1?
Its unsigned pattern is 18,446,744,073,709,551,615. Subtracting 2⁶⁴ gives -1.
Why is BigInt used?
Int64 values exceed JavaScript’s safe Number integer range, so BigInt is used to preserve exact arithmetic.
Can Int64 represent positive 9223372036854775808?
No. The maximum positive Int64 value is 9,223,372,036,854,775,807. Use UInt64 for positive 9,223,372,036,854,775,808.
Can I enter -1?
No. This calculator expects the raw two’s-complement hexadecimal pattern. Int64 -1 is FFFFFFFFFFFFFFFF.
Can I enter 0xFFFFFFFFFFFFFFFF?
Yes. One optional 0x or 0X prefix is accepted.
Can I enter fewer than 16 hex digits?
Yes. The raw value is normalized with leading zeros to sixteen hexadecimal digits.
Does this converter reverse byte order?
No. It preserves the hexadecimal byte order exactly as entered.

Convert Hex to Int64 Binary

Enter a raw hexadecimal pattern from 0000000000000000 through FFFFFFFFFFFFFFFF and select Convert Hex Int64. The calculator produces exactly sixty-four binary bits, checks bit 63 and returns the exact signed two’s-complement value using BigInt arithmetic.

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