During some collaborative work I’ve been asked to convert radiocarbon dates from BP into BC using OxCal, it’s pretty simple so I thought I’d write a little how to. This is useful if you are wanting to compare different dates from the literature but you only have the BP values.
Firstly, It’s best to use the online version of OxCal at https://c14.arch.ox.ac.uk there is also a download version but I’ve found it to be a bit blippy!
The program will ask for you to create a username and password. Once you have done this and can access the program you should get a screen which looks like this.
From here you need to go to file and select ‘new’. This will then open a new window which you can input dates into.
Then all you need to do is press ‘insert’ this will open a little tab for you to enter data into the fields.
For example enter the date I.D. into ‘name’ (GU-13906) the BP date (3475) into ‘C14 date’ and then the error (plus or minus 35) into ‘uncertainty’. Once you’ve entered the data then press the >> button. After this it will bring up the entered data in the blue box, you can then enter more dates (one at a time) into the R_Date tab.
Once you are done entering dates you need to press the blue arrow button in the top right corner (see above screen shot). This will open another window so you can name the file. As you can see I have a few saved projects!
Then press run and this will take you to the calibrated result
From this page you can look at the result or results in single plots (as above), multiple plots, or as a table.
I hope this is a useful demo, I may attempt a more complex one in the future! The OxCal website does have in depth instructions if you need them.