Can I just check that you mean Outlook on a PC? There used to be a Google tool that would do this, but it's been withdrawn. I have in the past tried a sync tool (not on Android), which corrupted the Outlook calendar and required a lot of manual repair. So, if you find anything, make a copy of your Outlook file before running it!
There is something called Sync2 which looks promising and it offers a 14 day trial,which may be enough if this is just a one-off transfer rather than ongoing synchronisation. I'm not sure whether Outlook for Android will sync with a desktop calendar - do you know, @63johnw?
To clarify: Google Calendar is the calendar that runs on Android and the best one to use on your phone. This will hold your calendar in the cloud, backing it up and making it available via the web or on any Android device that's signed into your Google account. I don't particularly like the front end and use aCalendar instead (there's a free version, but it's so good I opted to pay for it).
I use both Outlook and Google calendar, but keep them separate. It means duplication, but ensures I have belt & braces as well as avoiding any danger of corruption in the sync process. Same goes for Contacts.
Edited to add: another possibility, for a one-off transfer, would be to export your Outlook calendar in iCalendar format (File|Save As) and then import it into Google, is that's possible (I think it is).
