What UK property calculation do you wish was easier?

I built PropertyCalc after spending ages trying to work out stamp duty before my first home purchase. Every calculator was US-focused or ad-riddled.

So far there's stamp duty (with first-time buyer relief), mortgage repayments, take-home pay after tax, and rental yield. All free, no signup.

What would genuinely help you? Any calculation you always struggle with or end up Googling? Would love to build it.