Portland is about 3 times smaller than Amsterdam.

Amsterdam is approximately 166 sq km, while Portland (map shows its 17 named neighbourhoods; the area covers the whole city) is approximately 56 sq km, making Portland 33.66% the size of Amsterdam.
Tip: This to-scale comparison of Amsterdam vs. Portland 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.