This ratio starts at the atmospheric ratio when the organism is alive and decreases predictably as carbon-14 decays after death.

Measuring the remaining ratio and applying the known decay rate produces an estimate of time since death.

For the Shuká Káa remains, multiple radiocarbon measurements from different bone elements confirmed the age estimate and ensured that the result was not an artifact of contamination or measurement error.

The precision of the measurements — expressed as radiocarbon years before present plus or minus a specific range — reflects the statistical uncertainty of the measurement rather than any fundamental uncertainty about the age.

The conversion from radiocarbon years to calendar years (the familiar system based on solar years) requires a calibration step.