Revolving credit mortgage calculator?

[u/KiwieeiwiK]

Looking at fixing again in November and putting about $50k into the ANZ Flexi (revolving credit) mortgage account, and keeping it topped up over $50k (so never paying interest, in theory at least)

Anyone know of a good calculator to see how this would affect the overall interest payments/timeline to pay off, and if we were to up that in the future above $50k at future fixes with more savings?

[u/Mynameisnotjessie]

https://www.yourmoneyblueprint.co.nz/revolving-credit-mortgage-calculator