Summary

BIN2DEC converts binary text into a decimal number. If you have a string of 1s and 0s and want the regular base-10 value behind it, BIN2DEC does that translation.

This is useful when a worksheet stores low-level flags or status values in binary, but your analysis needs a normal number. Once you convert the value to decimal, it becomes much easier to compare, sort, filter, or use in other formulas.

Syntax

=BIN2DEC(number)

number is the binary value you want to convert.

You can type the binary value directly in quotes or point to a cell that already contains it. The result is a normal decimal number, so after the conversion you can use it in ordinary math, sorting, and comparisons.

Arguments

• number - [required] A binary value up to 10 characters long.

The input must be a valid binary value made only of 0 and 1. Excel allows up to 10 characters here, and at that length the leftmost bit is treated as the sign bit. If the text is too long or contains invalid characters, Excel returns #NUM!.

BIN2DEC vs similar functions

BIN2DEC is the right choice when the result needs to become a normal numeric value:

Using BIN2DEC

The simplest use is converting a bit pattern into a number you can work with more easily. A value like 1011 is clear if you think in binary, but many reports and calculations are easier in decimal, so BIN2DEC gives you that decimal result right away.

There is one important limit. BIN2DEC supports binary values up to 10 characters. Within that format, Excel treats a 10-character value whose leftmost bit is 1 as a signed negative number. That is why 1111111111 returns -1 instead of a large positive result.

Shorter binary values do not use that same sign behavior in the same way. For example, 10000001 is only 8 characters, so Excel reads it as the positive decimal value 129. That difference is worth remembering when you work near the 10-bit boundary.

Example 1 - Convert 1011 to decimal

This example shows the core use of BIN2DEC. The binary text 1011 represents 8 + 2 + 1, so Excel returns the decimal value 11. It is the simplest case of taking a bit pattern and turning it into a number that can be sorted, compared, and reused in later formulas.

=BIN2DEC("1011") // Returns 11

Example 2 - Read an 8-bit value

A full 8-bit string such as 11111111 is often easier to inspect in decimal once you no longer need to see each individual bit. BIN2DEC returns 255, which is useful when a binary flag field has to be reported as a normal integer or checked against numeric thresholds elsewhere in the sheet.

=BIN2DEC("11111111") // Returns 255

Example 3 - Decode a signed 10-bit value

This example matters because BIN2DEC treats 10-character binary inputs differently from shorter ones. The value 1111111111 is interpreted as a signed 10-bit number, so Excel returns -1 instead of a large positive result. That behavior is important whenever the worksheet stores signed engineering values in fixed-width binary form.

=BIN2DEC("1111111111") // Returns -1

Example 4 - Convert 10000001

This binary value starts with 1, but it is only 8 characters long, so Excel does not apply the 10-bit signed interpretation. The result is the positive decimal value 129. That contrast with the previous example helps explain why input width is part of the meaning of the value, not just its appearance.

=BIN2DEC("10000001") // Returns 129

Quick recap

• Converts binary to decimal: BIN2DEC returns a normal numeric value.
• Supports up to 10 characters: That is the main size limit for this function.
• 10-bit values can be signed: A 10-character binary value starting with 1 can return a negative result.
• Shorter values can still be positive: An 8-bit value like 10000001 returns 129.
• Useful for status and flag data: It helps when raw bits need to become readable numbers.