The .mpp file format
What is an MPP file?
An MPP file is a Microsoft Project plan. It is the standard format Microsoft Project desktop saves projects in, and it holds the whole schedule: tasks, durations, dates, dependencies, resources and calendars. It is a binary format that Microsoft does not publish, which is why most apps cannot open one. You can open it free with Onplana Schedule on Windows or Mac.
What is inside an MPP file
Everything Microsoft Project knows about the plan, not just a picture of it. That is what makes an .mpp more useful than a PDF or a spreadsheet export: open it in a scheduler and the plan still reschedules when something moves.
- Tasks and summary tasks, in an outline
- Durations, start and finish dates
- Dependencies between tasks, with lead and lag
- Milestones and constraints
- Resources, their assignments and costs
- Working calendars and holidays
- Baselines, progress and custom fields
MPP versions
Every .mpp ends in the same extension, but the format inside has changed over the years. An older copy of Project cannot open a file saved by a newer one. Current versions of Project open files from Project 2000 to 2003 but cannot save in that format.
| Format | Saved by |
|---|---|
| MPP14 | Project 2010 and every later version |
| MPP12 | Project 2003 and Project 2007 |
| MPP9 | Project 2000 and Project 2002 |
| MPP8 | Project 98 |
Related file formats
Checked on 29 September 2026 against MPXJ: How to read MPP files and Microsoft: File formats supported by Project desktop.
How to open an MPP file
With Microsoft Project on Windows, or free with Onplana Schedule on Windows or Mac. Onplana Schedule shows the plan as a Gantt chart with the critical path and float, lets you edit it, and saves it as Project XML, which Microsoft Project opens. The original .mpp is never overwritten. A binary .mpp is converted on Onplana's servers and the uploaded copy is deleted within 24 hours; Project XML files are read on your computer.
Step-by-step instructions, including the other free options, are in how to open an .mpp file without Microsoft Project. On a Mac, see Microsoft Project for Mac.
Questions
MPP files
What is an MPP file?
An MPP file is a Microsoft Project plan. It is the standard format Microsoft Project desktop saves projects in, and it holds the tasks, durations, dates, dependencies, resources, assignments and calendars of a schedule.
What opens an MPP file?
Microsoft Project on Windows, and apps that can read the format, such as Onplana Schedule (free, Windows and Mac), ProjectLibre and GanttProject. Onplana in the browser imports .mpp files into a shared project.
Can I open an MPP file without Microsoft Project?
Yes. Onplana Schedule is a free app for Windows and Mac that opens .mpp files as a Gantt chart with the critical path, lets you edit the plan, and saves it as Project XML. A binary .mpp is converted on Onplana’s servers and the uploaded copy is deleted within 24 hours; Project XML files are read on your computer.
Can Excel open an MPP file?
No. Excel does not read the .mpp format. Microsoft Project can export task data to an Excel file, or you can open the .mpp in a free app such as Onplana Schedule to read the schedule itself.
Is an MPP file the same as Project XML?
No. MPP is Microsoft Project’s binary format; Project XML is a text format that Project exports and imports. They carry much the same plan, and Microsoft Project opens both, but far more tools can read XML.
Why won’t my MPP file open in an older version of Project?
Each generation of Project writes a newer .mpp format. A file saved by Project 2010 or later uses the MPP14 format, which older versions cannot read. Current versions of Project open files from Project 2000 to 2003 but cannot save in that format.