Why file contents can exceed your Mac’s disk capacity

Logical size and physical allocation answer different questions. Here is how compression, sparse files and APFS sharing affect the numbers.

A file has more than one honest size. File contents, often called logical size, describes how many bytes an application sees. Disk space, or allocated size, describes physical filesystem blocks currently assigned to it.

Why the totals diverge

Compression can store a large logical stream in fewer blocks. Sparse files reserve logical ranges without backing every range with physical blocks. APFS clones can let files share backing storage. Cloud placeholders may describe content that is not fully local.

Adding logical sizes can therefore produce a number larger than the drive itself. That is not automatically an error, and it is not a promise that deleting those files would reclaim the same amount.

Which number should you use?

Use allocated disk space when asking what currently occupies local capacity. Use logical size when asking how much content software reads or might need when copied elsewhere. DiskKind keeps both views separate and labels unknown clone sharing instead of pretending it can be measured from ordinary metadata.