Speaking of handy little Mathcad tools, this one is a generic delta-v approximator for planet-to-planet Hohmann transfers, based on the same mathematics as this Stack Overflow answer:
As mentioned there, it makes various assumptions, including that the bodies’ orbits around their sun are within delta of circular and coplanar (which works reasonably well for Sol), and that you aren’t using low-thrust drives and as such it can get away with treating burns as instantaneous. The further you wander away from these, the more approximate the approximation gets, belike. Caveat calculator!
Anyway, here it is: