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Changing supported Windows UI font sizes with Font Size Tweak
What Font Size Tweak changes, how its per-user backup and restore work, and where Windows may ignore the classic font metrics.
- Authors
- Name
- Adam Johnston
- @admjski
Windows already offers text-size and display-scaling controls. Font Size Tweak is for a narrower case: adjusting five classic Windows interface font metrics individually, without changing the overall display scale. This guide describes the scope and recovery model documented by the Font Size Tweak source repository, rather than making a claim that every Windows application will respond.
What it changes
The utility reads per-user REG_BINARY values under HKEY_CURRENT_USER\Control Panel\Desktop\WindowMetrics:
| Control | Registry value | Commonly affects |
|---|---|---|
| Title Bar | CaptionFont | Classic window title text |
| Menus | MenuFont | Classic menus and context menus |
| Message Boxes | MessageFont | Some classic prompts and messages |
| Icons | IconFont | Desktop and supported File Explorer labels |
| Status Bar | StatusFont | Status text in compatible classic interfaces |
When it applies a size, the program preserves the existing binary font data and replaces its height field. The repository documents a size range of 8–16 pt, with controls to apply a value to all five metrics or adjust an individual one. Its interface and registry code are written in Python using ttkbootstrap and the Windows winreg API.
When to use it
The utility may help when a supported classic interface element needs a different text size but changing the overall scale is not the desired adjustment. It is not a replacement for Windows Accessibility settings. Microsoft documents a built-in Text size slider for enlarging text and a separate Scale control for changing the size of apps and other items; try those first if they solve the problem. See Microsoft's Windows text-size guidance.
Use the portable release carefully
The repository provides a portable executable for Windows 10 and Windows 11 desktop releases. It does not require installation or administrator rights because it writes values in the current user's registry hive. The project README links to the latest release and explains how to run from source.
Before applying a change, use the preview and start with a modest size. The repository describes a persistent original-settings backup in the user's %APPDATA%\FontSizeTweak folder. Restore uses the values captured from that computer, rather than assuming a universal Windows default. The backup is not stored beside the portable executable, so keep the profile backup if you move or replace the executable. The app also documents selected/all restore actions and a one-level undo; undo is held in memory and does not survive closing the app.
Know the limits
These are classic Windows metrics. Newer Windows components and individual applications may use different rendering paths, so not every control responds and results can vary by Windows component/build. The preview shows the selected point size; it is not a simulation of every interface. Some changes may not appear everywhere until you sign out and back in.
Font Size Tweak changes size only. It does not provide font-family, bold, italic, profile or preset controls. If a change makes the interface harder to use, restore the original captured values from the app before removing its profile backup.
For the project source, current release information and issue tracker, visit the FontSize Tweak project hub and its public repository.