Originally Posted by Kamadan

Not sure how you needed to do a "non scientific" calculation, as NZ clearly state how it works:

https://airnz.custhelp.com/app/answe...gh-fly-buys%3F


5.95 Fly Buys points = 1 Airpoints Dollars
Or
1 APD = 0.168 Fly Buys point

Also the myriad of partners have completely different earn rates, and on this page alone, lists NZ$10 = 1 point to NZ$50 = 1 point...
... although NZ$25/1 point seems to be the most common with say, supermarket (New World) and retail (Mitre 10, Noel Leeming etc.).

In which case to earn 1 Airpoints Dollars at a retail store means spending $25 x 5.95 = $148.75 per 1 APD. That's a reward rate of ~0.67%

A cash-back Credit Card is more rewarding at that rate.