For example a radiocarbon age of 4520 ± 30 BP calibrates to 3356−3101 cal BC with the Int Cal13 calibration curve at two sigma (95.4 %).The two sigma range is generally preferred since there is a 95% probability that the true age of the sample falls within this range.The program can be cited by the published description of a previous revision (Stuiver and Reimer, 1993) or the on-line version (Stuiver et al., 2005).
The current internationally-ratified calibration curve for terrestrial samples (e.g., woods, charcoals and macro-fossils) from the Northern Hemisphere is Int Cal04, which covers the past 26,000 calendar years (cal yr) (Fig. This curve is based on dendrochronologically-dated tree rings for the period 0-12,400 cal yr before present (BP, with 0 BP being AD 1950).
Thus, the automatic calibration result may contain warnings of the sample age being unsuitable for the calibration curve.
In addition to reporting radiocarbon ages we also report a quantity called F14C.
In most publications the raw radiocarbon age should be reported as well as the calibrated age range.
Our reporting process includes an automatic attempt at calibrating your radiocarbon result with an internationally agreed calibration curve.