This calculator will tell you how many more wishes you will need to guarantee any combination of 5-star characters and weapons based on your pity, primogems etc.
You will also be presented a graph showing the probabilities for lower amounts of additional wishes, the odds are calculated based on all possible 50/50 wins/losses combinations. (Capturing radiance makes this 55/45 for the character banner, assumed for simplicity)
There's also support for a 2nd account for those who need that. You can enable it as well as tweak some other parameters in the settings!
Everything is backed up in your browser locally as well, so you won't have to input all of your data every time.
I hope this is helpful to some. Good luck on your pulls! :)