Tidy MacGB to GiB converter for Mac storage
1 GB is 1,000,000,000 bytes; 1 GiB is 1,073,741,824 bytes, about 7.4% more. Finder uses GB, while du -h in Terminal uses GiB and labels it “G”. Convert any size below.
| Unit | Value | System |
|---|---|---|
| MB | 10,737.4182 | Decimal (Finder, drive makers) |
| GB | 10.7374 | Decimal (Finder, drive makers) |
| TB | 0.010737 | Decimal (Finder, drive makers) |
| MiB | 10,240 | Binary (du -h, df -h) |
| GiB | 10 | Binary (du -h, df -h) |
| TiB | 0.009766 | Binary (du -h, df -h) |
= 10,737,418,240 bytes
See your storage in plain numbers
Tidy Mac measures your storage in the same decimal units Finder uses, counts APFS clones once, and adds up to what Disk Utility reports. $9.99 once, 2 Macs.
How it works
Every value is converted to bytes and then divided by the size of each unit. Decimal units step by 1,000 (MB → GB → TB). Binary units step by 1,024 (MiB → GiB → TiB), so the gap grows with size: 2.4% at the KB level, 4.9% at MB, 7.4% at GB and almost 10% at TB.
Why the numbers differ. Drive makers and macOS Finder use decimal units, defined by the International System of Units. Many command-line tools, including du -h and df -h on a Mac and many Linux tools, count in binary units but print them with the same letters (G, GB). The IEC created the names KiB, MiB, GiB and TiB to tell them apart. No space is lost; it’s the same number of bytes written two ways. See checking disk space in Terminal for which command uses which.
Questions
Is 1 GB 1,000 MB or 1,024 MB?
In the decimal (SI) system that Finder and drive makers use, 1 GB = 1,000 MB = 1,000,000,000 bytes. The binary unit, 1 GiB, is 1,024 MiB = 1,073,741,824 bytes. Many tools write “GB” or “G” when they mean GiB, which is where the confusion comes from.
Why does my 1 TB drive show as 931 GB?
It doesn’t on a Mac: Finder counts in decimal units, so a 1 TB drive shows close to 1,000 GB of capacity. Tools that count in binary units show 1 TB (1,000,000,000,000 bytes) as about 931 GiB, often labelled “931 GB”.
Which units does du use on a Mac?
du -h and df -h use binary units and print them as K, M, G and T. df -H uses decimal units like Finder. So a folder du shows as 10G is about 10.7 GB in Finder.
Which units does macOS use?
Finder, Get Info and System Settings › Storage have used decimal units (1 GB = 1,000,000,000 bytes) since Mac OS X 10.6 Snow Leopard.