, I just eyeball it...
It's very difficult to get a trace much under 30 ohms, much over 150 ohms, or a velocity factor very different from 0.8 or so. This puts the inductivity right around 1.257 uH/m * (Zo / 377R) / 0.8 or ballpark 0.5 uH/m. 1nH/mm is a good worst-case starting point.
Then measure the length of the route, include ground return path if also routed (or poorly stitched), and there you have it.
Pathological cases obviously vary. Not really pathological, it's just proportional. A 10cm wide power pour has a Zo of, say, a few ohms, and near nil inductance.
I was building another power supply, with about 20nH stray from filter caps to half bridge. (The path length is, yup, just over an inch round trip.)
The SuperJunction transistors ring like crazy at 60MHz. The risetime is so fast, it excites everything it can. (It's not an active oscillation -- the gate drive is fairly weak, and ferrite beaded. The ringing is caused by the opposite side switching on.)
At a switching frequency of 300kHz, I can't use ferrite beads on the drain to dampen the ringing. I mean I can, but it only works for a few seconds, then the bead thermoregulates at ~100C (NiZn type, so the Tc is kinda gross). I've made a low temp Metcal tip, not a damper!