How to make bootable Debian USB on mac?

I didn't convert the ISO to img, I just formatted a USB drive for FAT and used dd:

sudo diskutil unmountdisk /dev/disk1
sudo dd if=./debian.iso of=/dev/disk1 bs=1m

I tested this with Debian 9.

It's important to note that the appropriate /dev/disk# should be determined by using the following command on the macOS command line:

diskutil list

In the question above, the USB device mapped to /dev/disk2 whereas the example above uses /dev/disk1. But the number could be 3 or 4 or some other number. Ensure the number correlates with the memory stick you use; you risk losing data if you get it wrong.

Use unetbootin : https://unetbootin.github.io/. Here is a tutorial for ubuntu but you can also use it for debian just change the image :http://www.ubuntu.com/download/desktop/create-a-usb-stick-on-mac-osx