The size of these mittens is adjustable by changing the gauge.

If you change it up you will get a smaller mitten.
If you change the gauge down the mittens will be bigger.

You change the gauge by changing needles and/or the weight of your yarn.

You will need one skein of each color.
And about a total of350-500 meters.
Depending on what kind of cuff you choose to knit your yardage might change.