Build Size Diff

Compare two builds and see exactly what grew. Every number is read from the BuildReport Unity writes at the end of a build, so nothing is estimated. Set a budget and it fails CI when a build goes over it.

$29one-time · Unity Editor tool · ZIP (34 KB)

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Build Size Diff window: +2.0 MB, over the allowed 1.0 MB — Two real macOS builds compared with a 1 MB budget: +2.0 MB (+2.0%), 100.1 MB to 102.1 MB, over budget.

What it reports

The assets that grew, by name, with packed sizes, ordered by how much they moved, separated into grew, added, removed and shrank.
Growth and savings are kept apart, so a regression hidden by an unrelated saving still fails.
Four independent CI budgets (total bytes, total percent, per-asset growth, new asset size), exit code 2 when one is exceeded. With no budget set it only reports.
An unreadable budget stops the run instead of silently disabling the check. A cross-platform comparison fails by default instead of printing a meaningless delta.
Markdown for a pull request comment and JSON for everything else, from the same comparison. An Editor window and two batch mode entry points.

Measured, not claimed

Verified end to end on macOS (StandaloneOSX), Unity 6000.0.78f1: two real player builds, with one 2.0 MB asset added between them.

Check	Result
Total	100.1 MB → 102.1 MB (+2.0 MB, +2.0%)
What grew	one new asset, `Assets/Resources/blob2.bytes` (TextAsset, 2.0 MB), and nothing else
Budget 1 MB	fails, exit code 2
Larger budget	passes

Added tab listing the one new asset — The Added tab: the one new asset.

Unity versions

Tested on Unity 6000.0.78f1 (Unity 6), macOS Editor: the EditMode tests (44 tests, all passing) and the runs described on this page.
The package declares Unity 2022.3 as its minimum. It has not been tested on 2022.3. If it does not work there, the refund below applies.
Editor-only: no runtime code, nothing is added to your builds. No dependencies.

How this was made: AI disclosure

The C# code, the EditMode tests, the documentation and this page were written with the help of a large language model, then read, run and corrected by a person before release. No figure on this page was written by the model: every number comes from running the tool on a real Unity project and reading its output, and every screenshot is a capture of the tool's own window in Unity.

What you get

A ZIP (34 KB) with the .unitypackage (19 files: full C# source, EditMode tests, documentation, two demo snapshots), the license and the changelog.
Import it with Assets > Import Package > Custom Package…. It installs under Assets/Build Size Diff/.
Updates: re-download the current version at any time from your thanks page (the link is in your email).

License

One purchase is one licence for one person. Use it in any number of your own projects, commercial or not, modify the source for them, and run it on the build and CI machines that build them.
Not allowed: redistributing or reselling the tool or its source, or sharing your copy with people who have not bought one.
The full text is LICENSE.md in the package.

Payment and refunds

Card payment via Stripe, one time. A license key and a download link are emailed to you and shown right after payment.
Refund within 14 days of purchase, no reason needed, as stated in our legal notice: email hello@tech-athletes.com. After a refund the download stops working.