Chance for 1 of the possible rate-ups:

0.8%

Remember to verify this chance! See links below
This information is based on historical chances, so be sure to double-check

Note that banners with multiple servants on rate-up of the same rarity don't always have equal percentages
Some 5* banners will have 0.4% for one 5* and 0.4% for another, but another banner could have 0.5% for one and 0.4% for the other
We don't necessarily know these rates ahead of time, but it is typically split evenly between all cards of the same type and rarity

You can always (and should!) verify the chance of getting what you want like this:
Click here and Then look here