As Stef mentioned, this is due to the difference between how file sizes are calculated.
The Processing website calculates using binary units (1 MB = 1,048,576 bytes).
macOS Finder reports sizes using decimal units (1 MB = 1,000,000 bytes).
That’s why the same file shows up as ~410 MB on the site but ~429 MB once downloaded.
Both numbers are correct, they’re just using different definitions of “MB.”
User thomas_r on the macOS community forum gave this explanation for why macOS uses decimal units:
The Mac is reporting file size in megabytes. Windows is reporting file size in mebibytes. The difference is that a megabyte is 1,000,000 bytes, while a mebibyte is 1,048,576 bytes. This change was made in Mac OS X so that reported disk sizes would agree with manufacturer's claimed sizes... most manufacturers claiming a size of 500 GB mean 500,000,000,000 bytes. Mac OS X will also call that number of bytes 500 GB, while Windows will call it 465.7 GB. That confused a lot of people.
12. @catilac Can you please mention / attach the PR solved this? Thanks.
From the conversation above, it seems to me the consensus was that no change was needed, since the difference comes from how file sizes are calculated and displayed. Closing the issue as not planned might have been slightly more accurate than completed, but it's a minor distinction, and could be inferred from context imo. Let's try to keep our attention focused where it matters :)
Closing the issue as not planned might have been slightly more accurate than completed
Yep :)
it seems to me the consensus was that no change was needed,
Wouldn't say so. I thought this was handled during the other website changes.
Let's try to keep our attention focused where it matters :)
I support the sentiment, but a note / proper resolution status always helps other people following up these issues and creates better historical records.
True as this may be, perfect is the enemy of done, and maintainer attention is a scarce resource. I invite everyone to use their best judgment when deciding where to request extra care, so we can focus our very limited resources where they make a real difference.
Activity
Stefterv commented on Sep 7, 2025
processing-website/src/hooks/download.js
Lines 38 to 48 in 7dedfc0
The amounts are all correct I suspect its the age old how many bytes in a kilobyte
SableRaf commented on Sep 7, 2025
Thanks @kfahn22 for reporting this!
As Stef mentioned, this is due to the difference between how file sizes are calculated.
That’s why the same file shows up as ~410 MB on the site but ~429 MB once downloaded.
Both numbers are correct, they’re just using different definitions of “MB.”
User thomas_r on the macOS community forum gave this explanation for why macOS uses decimal units:
Source: https://discussions.apple.com/thread/3440708?answerId=16545377022&sortBy=rank#16545377022
ulgens commented on Aug 28, 2026
Firefox:
Chrome:
Finder:
While this is a bit annoying, I think the value on the webpage matches where it matters.
ulgens commented on Oct 25, 2026
@catilac Can you please mention / attach the PR solved this? Thanks.
SableRaf commented on Oct 25, 2026
From the conversation above, it seems to me the consensus was that no change was needed, since the difference comes from how file sizes are calculated and displayed. Closing the issue as not planned might have been slightly more accurate than completed, but it's a minor distinction, and could be inferred from context imo. Let's try to keep our attention focused where it matters :)
ulgens commented on Oct 25, 2026
Yep :)
Wouldn't say so. I thought this was handled during the other website changes.
I support the sentiment, but a note / proper resolution status always helps other people following up these issues and creates better historical records.
SableRaf commented on Oct 25, 2026
True as this may be, perfect is the enemy of done, and maintainer attention is a scarce resource. I invite everyone to use their best judgment when deciding where to request extra care, so we can focus our very limited resources where they make a real difference.
ulgens commented on Oct 25, 2026
Thanks for the update 🌻