I never get it right. At 5'6", "belly high" surf is chest high for me and I can get covered up. "Chest high" according to the forecast is pretty much overhead for me. I go by the face, and whether or not the person I am talking to was there. If you weren't there, it was 6'. If you were, it was probably 2-3. Similarly: If you weren't there, I got pitted. If you were there, I got sprayed and couldn't see for 2-3 seconds.
Surf heights are always going to be a little subjective from the viewer, but the key is to be consistently subjective. So, Swellinfo is always going to call 4ft @ 10 seconds from the SE, the same every time...
As soon as my Stars n Bars SUP with the stripper pole gets out of the shop. It's being fitted with a new rustproof L-Z-Boy recliner and a rod holder.