# Understanding what a scale outputs and converting between Mass and Weight

I understand that weight is a measure of force acting on an object due to gravity and mass is a measurement of the quantity of matter than an object contains. With mass having units of kilograms or slugs and weight having units of newtons or pounds.

1. Based on my research online I see that scales on earth are calibrated for earth (via a spring constant, piezoelectric material, etc. means of measurement depending on the type of scale). But it is not clear to me if it gives a mass of say 70kg on earth would that mean that I would also be 70kg on the moon? Using that particular scale it probably would not read right, correct? But a scale with a calibrated measuring device should give me 70kg on the moon as well since that is a unit of mass?

2. Are weighing scales we typically use at home measuring mass or weight? The output tends to be in kg OR lbs which is baffling to me because they are giving a measure of mass OR weight? It seems we can convert a kilogram to pound by multiplying 1kg by 2.2046, how is it that we can directly convert from a unit of mass to a unit of weight like this?

Most probably your home device is actually a scale and is somehow measuring the force imparted by whatever you put on the platform due to your local gravity. The function to display the result in either kilograms (mass) or pounds (force) is typically just a software conversion that assumes that your local gravity is a standard value for Earth, which is to say $$g$$ given approximately as $$9.8\ \mathrm{m/s^2}$$ or $$32\ \mathrm{ft/s^2}$$, depending on which system of units you are using.
Since this is typically not just a conversion from mass to force but also between metric and Imperial units, you can think of having two steps. Starting in pounds first "convert" to mass (slugs) staying within Imperial using the value of $$g$$ and then convert from Imperial to metric.