Hey :-) So four of the UKCAT sections (VR, QR, AR and DM) are marked on a scale of 300 to 900 with 600 said to be average and everything over 700 being good. Nobody really knows how the raw scores relate to the final score out of 900 but many people use the technique of working out a percentage of 600 and adding 300 during their practice. However, to confuse matters further, it is possible to get a 'perfect' score of 900 without getting all the of questions correct! It's a bit like UMS in that way.
The SJT section of the UKCAT is marked very differently using a banding system. Band 1 is the best and band 4 is worst. Everybody should be aiming for band 1 or 2.
Hope that helps,
Alex, 4th year UCL medic
6med