Flag Size for 1/700 Destroyer

What Bill said. National flag size can be somewhat arbitrary (I've seen pics of US warships flying a Stars and Stripes almost the size of a barn door). The important thing is if you're modeling your ship as under way (national flag on the mast) or in port, (national flag at the stern).

Thanks Bill!

Per some photos online, the ARA flew the National Ensign from the stern while in port (and tied up), and at the mast while underway. Like the USN does.

Hercules flew hers at the foremast (or whatever the front one would be called here), above the cross yard and on the starboard side.

AFA size?

A mid sized USN Ensign would be about 5 feet hoist and 9 feet length. Or 0.08 in. x 0.15 in. at scale.

Bill