As you use Spire, it is sensing your 'baseline' respiration rate and consistency and using this information to determine when you are breathing slower, faster, more erratic, or more consistently than you normally do. Hence, the algorithms are tailored to you – and this profile of you is evolving over time as well. In this way, Spire can evolve with you.
Spire measures Calm by sensing when your breathing rhythm is slow and smooth, while your body is stationary.
Spire measures Focus by sensing when your breathing rhythm is at a medium speed yet consistent, while your body is stationary. This can occur whether your bpm is above or below your baseline breath rate.
Spire measures Tension by sensing when your breathing patterns are elevated and erratic, while your body is stationary.