Appearance
iTerm2 Cell Size Reporting (OSC 1337)
OSC 1337 ; ReportCellSize queries the terminal for the dimensions of a single character cell in pixels. The response is OSC 1337 ; ReportCellSize=height;width ST. This is essential for pixel-accurate image rendering protocols (sixel, iTerm2 inline images, kitty graphics) where applications need to know the exact pixel dimensions of cells to scale images correctly.
How this is tested: Send
OSC 1337 ; ReportCellSize BEL and verify the terminal responds with cell dimensions.Analysis2026-03-26
Supported by 2 of 13 backends (15%)
Terminal Applications
| Terminal | Version | Support | Notes |
|---|---|---|---|
| iTerm2 | 3.6.9 | ✓ yes | |
| Ghostty | 1.3.1 | ✗ no | iTerm2-specific protocol not supported |
| VS Code | 1.112.0 | ✗ no | No OSC 1337 ReportCellSize response |
| Warp | 0.2026.03.18.08.24.03 | ✗ no | No OSC 1337 ReportCellSize response |
| Cursor | 2.6.21 | ✗ no | No OSC 1337 ReportCellSize response |
| tmux | 3.6a | ✗ no | iTerm2-specific protocol not supported by tmux |
| Kitty | 0.46.2 | ✗ no | iTerm2-specific protocol not supported by kitty |
| Terminal.app | 2.15 | ✗ no | No OSC 1337 ReportCellSize response |
| GNU Screen | 5.0.1 | ✗ no | iTerm2-specific protocol not supported by Screen |
Headless Backends
Parser correctness only — a ✓ means the parser accepts the sequence.
| Backend | Version | Support | Notes |
|---|---|---|---|
| vterm | 0.2.0 | ✓ yes | |
| Alacritty | 0.26.0 | ✗ no | iTerm2-specific protocol not supported |
| vt100 | 0.2.1 | ✗ no | iTerm2-specific protocol not implemented — pure TypeScript emulator |
| WezTerm | 0.1.0-fork.5 | ✗ no | iTerm2-specific protocol not supported |