Where to find interbank and MasterCard exchange rates together?

Nickjk

Hi
I am trying to compare the Halifax clarity card with the Currensea card, so I need to find both the MasterCard exchange rate (for clarity) and interbank exchange rate (for Currensea) at any point in time, but I cannot find any resource that would allow me to easily compare the two.
Because Currensea adds 0.5% to the interbank rate, I need the MasterCard rate to be at least 0.5% worse than the interbank rate to make it worth using.

Any resources that will make this easy?
Cheers.

NoodleDoodleMan

Does this help, even partially ?

https://www.mastercard.co.uk/en-gb/consumers/get-support/convert-currency.html

Nickjk

Thanks - I had seen that, and it's useful for a single transaction, but I need to find the comparison over time to work out if it's 0.5% different, that's what I'm missing!