The temperature shift your cycle produces
TEMPERATURE
Accuracy
0.046 °C
Average Variation Around a Steady Offset
how far a reading strays from the steady 0.11 °C offset between the two sensors, against a 0.26 °C luteal shift
Reference standard
OvuSense reference sensor
Sample size
Based on 557 paired readings
On the bench the Ultrahuman Ring holds a steady offset from the OvuSense reference sensor, and a reading strays from that offset by 0.046 °C on average — a fraction of the 0.26 °C post-ovulatory shift observed in Ultrahuman production data.
0.046 °Cthe average stray from the steady offset
0.11 °Cthe steady offset between the two sensors
0.26 °Cthe luteal shift at the finger
5.7×smaller than the shift the cycle produces
Temperature-based cycle tracking reads one thing: the small, sustained step up in body temperature that follows ovulation. After ovulation, the emptied follicle becomes the corpus luteum, which releases progesterone and raises basal body temperature. It usually stays elevated through the luteal phase, then falls just before or around the start of the next period. The catch is the size of it. The whole signal is a few tenths of a degree — the core-temperature literature puts that rise at 0.3 to 0.5 °C, and measured at the finger, where this sensor sits, the step is about 0.26 °C in Ultrahuman’s own production data — far too small to feel and easily lost in an ordinary night of warming up and cooling down.
On the bench, against the OvuSense reference sensor, the Ultrahuman Ring held a steady offset and strayed from it by 0.046 °C on average — about a fifth of the rise it is looking for.
The two sensors sit a steady 0.11 °C apart, with 95% of readings inside a 0.22 °C band around that offset. A constant offset moves both sides of a step by the same amount, so what a bench comparison of two datastreams settles is how steadily they track each other rather than how far apart they sit.