Bern is about 13 times smaller than Tehran.

Tehran is approximately 686 sq km, while Bern is approximately 52 sq km, making Bern 7.52% the size of Tehran.
Tip: This to-scale comparison of Tehran vs. Bern uses the Mercator projection, which distorts the size of regions near the poles.
Our free app, MapSize by MyLifeElsewhere — compare any two places, to scale on your mobile device.