Minimum mass (M sin i)

When a planet is found by the wobble it tugs in its star (the radial-velocity method), the measurement gives its mass multiplied by the sine of the orbit's tilt, written M sin i. Because we usually do not know that tilt, the result is a minimum: the true mass is this value or larger, and only rarely much larger. If we happen to catch the orbit edge-on, the minimum is essentially the real mass.

This matters because mass drives gravity, and gravity drives what it would feel like to stand there. gravityfinder never dresses a minimum up as a certainty: where a planet's mass is a lower bound, its gravity and your weight are shown as "at least" figures rather than exact ones. It is one of the three ways the site grades how well a mass is actually known.