Vietnam covers 328,959 km² km² on the new Equal Earth world map — 0.2%% of all land on Earth, making it the 67th largest country in the world and the 18th largest in Asia. At 17° latitude Mercator only inflates Vietnam by about 9%%, so the old and new maps largely agree on it — unlike the far north, where Mercator's stretch is dramatic.
For scale: Vietnam is roughly the same size as Malaysia (327,621 km² km²).
You could fit 3 of Cuba inside Vietnam.