Every few years, the radiocarbon calibration curve used to determine the calendar dates of almost all 14C measurements gets updated. The last recalibration was in 2013. Called IntCal13, it was based on 7,019 raw data points. This year, a major revamp – one of the biggest since its inception – has taken place and the new IntCal20 now takes into consideration more than 12,900 measurements. As with previous versions, the separate curves for samples from the Southern Hemisphere (SHCal20) and from marine reservoirs (Marine20) have also been updated. In this month’s ‘Science Notes’, we break down the history of these curves and dissect some of IntCal20’s new ‘features’.