You can use the sp_to_vests() function in the steem-python module (http://steem.readthedocs.io/en/latest/tools.html#steem.converter.Converter.sp_to_vests) to calculate how many VESTS you have from the amount of STEEM POWER you have. Otherwise, 1 MVEST (1 million VESTS) = 482.692 STEEM POWER (per steemdb.com), so 1 VEST = 0.000482692 STEEM POWER.