That said the NZ converter is going via a web archiver, so no promises the calculations are correct there either, depending on the scripting in use - because the site no longer exists.
It isn't so critical whether the site exists or not. This calculator/ready reckoner is a Javascript script - so without too much trouble, you can see the values/assumptions that will be used in the calculations. As it all happens 'client-side', you can see all the code in plain text. Just get on the page, right click and choose View Page Source. But even easier is the suggestion to put a 1 in the first box and calculate to see what it is doing...
This was really my first foray into scripting (well, copy/paste and changing, mostly!). Several years ago, a guy got in touch with me about him wanting to develop an Apple app with the various calcs in it. I told him, too, there was no 'magic' in the calculations - all just 'visible' for people to see. I've never done Apple stuff, so don't know if he ever got around to doing it, but he seemed keen.
@John B - that 60 frames/hr was always my target, but I couldn't sustain it. I'd need 10 min off after doing an hour. Mostly 3 wire. I hated it, but did it.
But it was
those ones - ones that weren't just inches to metres sort of 'automatic' things - that I enjoyed collecting. Like asking a bunch of beekeepers at a field day "How much paraffin wax do you use for each FD box you dip?" and seeing what sort of range of answers you'd get.
But again, 'back then' (don't move this to Historical Beekeeping!!!) beekeepers tended to make a lot more things, and do a lot of jobs that now are relatively easy to contract out.
I gotta say I don't want to wire any more frames...