Results of carbon-14 dating are reported in radiocarbon years, and calibration is needed to convert radiocarbon years into calendar years.
Uncalibrated radiocarbon measurements are usually reported in years BP where 0 (zero) BP is defined as AD 1950.
It is calculated on the assumption that the atmospheric radiocarbon concentration has always been the same as it was in 1950 and that the half-life of radiocarbon is 5568 years.
For this purpose `present' refers to 1950 so you do not have to know the year in which the measurement was made.
BP stands for “Before Present” or “Before Physics” as some would refer to it.
It should be noted that a BP notation is also used in other dating techniques but is defined differently, as in the case of thermoluminescence dating wherein BP is defined as AD 1980.
For two important reasons, this does not mean that the sample comes from 3619 BC: Many types of tree reliably lay down one tree ring every year.
Beta Analytic’s biggest advantage over low-cost university competitors is its fast turnaround time – 14 business days or less. (Universite de Paris Sorbonne) and Jerry Stipp, Ph. (Australian National University) founded Beta Analytic, Inc., in 1979.
Beta Analytic’s core business is the radiocarbon dating of geological, hydrological, and archaeological materials. They have both been instrumental in the development of radiocarbon dating as a method since 1959 and have published more than 100 papers on radiocarbon dating, geochronology, and hydrology.
Radiocarbon measurements are always reported in terms of years `before present' (BP).
This figure is directly based on the proportion of radiocarbon found in the sample.