What is the PLAN file format?
A .plan file is a project-management document created by Calligra Plan, part of the KDE Calligra Suite. The format originated as the KPlato project file (from 2004) and was rebranded when Calligra 2.4 shipped in April 2012.
Despite the .plan extension, this is not a CAD or architectural drawing. It stores a complete project schedule: tasks, durations, dependencies, milestones, assigned resources, calendars, and computed schedule results including Gantt chart data.
Internally the file is a ZIP archive - identifiable by the PK magic bytes at offset 0 - that packages an XML project document alongside a plain-text mimetype marker, following the same OpenDocument container convention used by formats like .ods. The registered MIME type is application/x-vnd.kde.plan.
Calligra Plan runs on Linux, Windows, and macOS, though obtaining a working build can require effort as the project has been largely unmaintained since the mid-2010s. To move a project to another tool, use Plan's built-in PDF export for reports or its interchange-format export options. Users migrating away from Calligra Plan sometimes convert schedules manually to tools such as GanttProject or ProjectLibre, or export to .mpp-compatible formats.
Security & safety
RISK: LOWA Calligra Plan .plan is project data (a ZIP of XML), not an executable, so opening it in Calligra is safe. The realistic concerns are non-malware: a project file can hold confidential schedule, resource and client information, so treat shared files as sensitive; and because the .plan extension is reused by unrelated software, don't assume an unknown .plan is a Calligra project - identify its source. Download Calligra only from calligra.org/official distro repositories to avoid adware-bundled installers and fake 'plan viewer' sites.
Format details
in a nutshell- Microsoft Flight Simulator / FSX flight plan (.PLN/.plan) - MSFS, FSX and Prepar3D save XML-based flight plans (route waypoints), unrelated to project management; opened in the flight sim or a flight planner.
- Plain-text 'plan' / finger .plan file - Classic Unix users kept a free-form text .plan shown by the 'finger' command; just a text file, openable in any editor.
- Generic application plan/config file - Some other tools save their own 'plan' or layout data as .plan; meaning depends on the producing program.
Programs that open PLAN files
Windows1 app
Calligra (Windows build)
Open-source Install a Calligra Windows build that includes Plan and open the .plan. Windows builds lag the Linux version; if Plan isn't included, use a Linux/VM route. 
macOS1 app
Calligra (macOS build)
Open-source Use a Calligra macOS build with the Plan component to open the .plan; availability varies by release. 
Linux1 app
Calligra Plan (Calligra Suite)
Open-source Install Calligra (your distro's package or Flatpak) and open the .plan in Plan to view/edit the project schedule. The most reliable platform for Plan. Technical details
deep spec| Container format | ZIP archive using the OpenDocument/Calligra package convention |
| Internal encoding | UTF-8 XML project data |
| Magic bytes | 50 4B 03 04 ("PK") at offset 0 - generic ZIP signature; true identity confirmed by internal layout and mimetype entry |
| MIME type | application/x-vnd.kde.plan |
| Compression | DEFLATE applied per ZIP entry |
| Integrity check | CRC-32 per ZIP entry; no additional checksums |
| Project data stored | Tasks, durations, dependencies, milestones, assigned resources, calendars, and computed schedule results |
| Schema lineage | Descended from the KPlato XML project schema (KDE, introduced 2004); versioned with Calligra releases |
| Scheduling method | Critical Path Method (CPM); computed results are serialised inside the XML alongside the task definitions |
| Internal layout | Flat-text mimetype entry + XML project document + optional embedded resources, all packaged inside the ZIP |
| Typical file size | 10 KB to a few MB depending on project complexity |
| Supported platforms | Linux (primary), Windows, macOS (via Calligra suite builds) |
| Maintenance status | Largely unmaintained since the mid-2010s; obtaining a working build may require compiling from source |
| Export paths out | PDF (schedule reports and Gantt views); iCalendar; manual migration to GanttProject or ProjectLibre |
| Released | 2012 (Calligra Plan branding, Calligra 2.4); as KPlato from 2004 |
| Latest version | Calligra Plan (last active Calligra releases; project now low-maintenance) |
| Open standard | Yes · royalty-free |
| Specification | calligra.org |
PLAN conversions
Community Q&A
asked by usersNo questions yet - be the first to ask about PLAN files.
