STM32CubeIDE memory usage units (KB vs KiB) inconsistency

[Hadi_sy3]

Dear STM32CubeIDE Support Team,

while analyzing the memory usage of my STM32 project, I noticed a potential inconsistency in how memory units are displayed in STM32CubeIDE.

Both the Build Analyzer and the memory overview label the values as “KB”, but the reported numbers clearly correspond to KiB (1024 bytes) rather than kB (1000 bytes). This behavior matches the output of arm-none-eabi-size, which reports sizes in bytes.

For example:

• arm-none-eabi-size reports Flash usage as:

  • text + data = 64824 + 148 = 64972 bytes

• Converted to kB (1000 bytes), this would be:

  • 64.972 kB

• However, STM32CubeIDE displays:

  • 64972 / 1024 = 63.45 KiB, while labeling the unit as “KB”

As a result, summing RAM and Flash values only produces consistent results when interpreting the displayed “KB” values as KiB. The current labeling can therefore be confusing, especially when documenting or comparing memory usage.

I have attached two images that illustrate this behavior and show the comparison between arm-none-eabi-size and the STM32CubeIDE memory analysis.

I wanted to report this observation and ask whether the use of the “KB” label is intentional or if a clarification or correction is planned.

Thank you for your time and support.

Best regards,
Hadi Althiab

[unsigned_char_array]

The world uses it inconsistently:

• RAM manufacturers use 1024
• non volatile storage manufacturers use 1000 if the unit is Bytes (i.e. 1TB SSD)
• non volatile storage manufacturers use 1024 if the unit is bits (i.e. 1kbit EEPROM)
• Prior to 2009 Apple used 1024, after 2009 they use 1000
• Windows and Linux use 1024
• for network speed 1000 is used

In my code I always use KiB for 1024 to avoid ambiguity.

[gbm]

"kiB" does not exist. KiB is the right symbol.

And mass storage manufactures use GB/TB because 1 TB SSD sells better than 960 GiB one although its exactly the same unit.

[unsigned_char_array]

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@gbm wrote:

"kiB" does not exist. KiB is the right symbol.

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I never knew. In SI a kB has lower case k to distinguish it from Kelvin. In SI all preferences below 10⁶ are lower case. But I guess binary prefix breaks consistency with SI here and instead has internal consistency by making them all upper case.