Chart your temperature and watch the shift appear

Take it first thing, before sitting up, talking, or drinking, at roughly the same time each morning, after at least three hours of continuous sleep. Use the same thermometer and the same site every day. A basal thermometer reading to two decimal places makes small shifts visible.

The coverline sits 0.1°F above the highest of the six readings before a rise. When three consecutive readings hold at or above that line, the shift counts as confirmed and ovulation is placed on the day before the first of those three.

No. The temperature rise follows ovulation rather than announcing it, so a chart confirms what already happened. Across several cycles the pattern shows roughly when you tend to ovulate, which is the useful part. For this cycle, cervical mucus and ovulation tests give notice that a chart cannot.

Mark it unreliable. Illness, a fever, alcohol, a broken night, or a reading taken much later than usual can all move a temperature enough to create a false shift. Flagged readings stay visible on the chart but are left out of the coverline calculation.

Usually about 0.5 to 1°F, or roughly 0.3 to 0.6°C, sustained until the next period. It is a small change, which is why a consistent routine matters more than an expensive thermometer.

In this browser only, so the chart survives a refresh. They are not sent to Flowy, do not sync to another device, and are deleted if you clear site data. Export a CSV if you want a copy to keep or take to an appointment.