How do I recalibrate Boost?

There are two ways. You can press the Calibrate button in the top right of any workout screen in the app (during a workout).

Or, anytime Boost is turned on, you can recalibrate by briefly pressing the Power button on Boost (if you hold it down too long, though, you’ll turn Boost off).

Whenever you recalibrate, it will cause Boost to re-zero the measurement baseline at the instant that you calibrated, so try to have good posture and fully relax your pelvic floor muscles when you do it.