What is the CRTX file format?
.crtx is a chart template file format used by Microsoft Excel, Word, and PowerPoint (Office 2007 and later). .crtx files store chart formatting information - settings for text, color, gridlines, axes, legends, titles, and other visual elements - but contain no data of their own. Internally, a .crtx file is a ZIP archive package following the Office Open XML Open Packaging Conventions (OPC), holding a small set of XML parts: chart1.xml (chart definition), style1.xml (part formatting), colors1.xml (color scheme), and themeOverride1.xml (theme override). It replaced the older binary .crt chart template that predated Office 2007.
Uniform style settings for charts
.crtx chart templates can be used to apply the same styles and formatting to multiple charts, allowing users to quickly and efficiently create many documents with consistent visual settings. A template captures the chart type, axis configuration, series appearance, color palette, and theme - everything except the underlying data.
Additional information
An existing chart can be saved as a template by right-clicking it in Excel or PowerPoint and choosing "Save as Template," which exports its settings into a .crtx file stored in the user's Charts template folder. Because the container is a standard ZIP package, renaming a .crtx copy to .zip lets you inspect or edit the XML parts directly with any text editor.
Security & safety
RISK: LOWA CRTX is plain chart-styling XML in a ZIP and contains no macros or executable code, so it is low-risk to open. It does carry no data, so it can't leak spreadsheet contents. As always, only run the actual chart in a trusted Office install; the template itself is inert.
Format details
in a nutshell- Corel Painter brush variant (.crtx-like) - Some Corel/creative tools use similarly named template/variant files; rare and unrelated to the Office chart template.
Programs that open CRTX files
Windows3 apps
Microsoft Excel
Paid Insert/select a chart > Chart Design > Change Chart Type > Templates, and pick the saved .crtx. Or right-click a chart > Save as Template to create one. 
7-Zip
Open-source Right-click > Open archive to inspect the XML parts (it's a ZIP); read-only, won't apply the template. 
Microsoft Word / PowerPoint
Paid Insert a chart, then Change Chart Type > Templates to apply the .crtx. 
macOS1 app
Microsoft Excel for Mac
Paid Same workflow: Chart Design > Change Chart Type > Templates, choose the .crtx. Technical details
deep spec| Container format | ZIP archive following Office Open XML Open Packaging Conventions (OPC) |
| Internal encoding | XML (UTF-8) across all content parts |
| Compression | DEFLATE per-entry ZIP compression |
| File signature (magic bytes) | 50 4B 03 04 ("PK") at offset 0 - standard ZIP local file header |
| Primary MIME type | application/vnd.ms-office.chartex+xml |
| Typical file size | 5 KB - 50 KB (a handful of small XML parts) |
| Key internal parts | `chart1.xml` (chart definition), `style1.xml` (part formatting), `colors1.xml` (color scheme), `themeOverride1.xml` (theme override), `[Content_Types].xml` |
| XML namespaces | DrawingML chart schema (c: namespace); chart-style schema (cs:) and chart-colors schema (cl:) |
| What it stores | Chart type, axes, gridlines, series formatting, color palette and theme - layout only, no embedded data |
| Supersedes | Legacy binary .crt chart template (pre-Office 2007) |
| Default save path (Windows) | %APPDATA%\Microsoft\Templates\Charts\ |
| Integrity checking | Per-entry ZIP CRC-32 checksums; no document-level digital signature |
| Encryption support | None - no built-in encryption layer |
| Supported platforms | Windows and macOS via Microsoft 365 / Office 2007 and later |
| Released | 2007 (Office 2007 charting engine; replaced the legacy .crt chart template) |
| Latest version | Tied to the OOXML chart schema (DrawingML chart); current with Microsoft 365 |
| Open standard | Yes · royalty-free |
| Specification | learn.microsoft.com |
CRTX conversions
Community Q&A
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