Air Canada and United Airlines with Star Alliance partner flights in Europe have San Francisco to Copenhagen as low as $422 round trip in May and $533 in July.
Copenhagen is a convenient and efficient airport for low cost flights to many places around Europe.
Air Canada San Francisco – Montreal YUL – Toronto YYZ – Copenhagen CPH – Toronto YYZ – SFO
$421.78 round trip Wed May 2 – Fri May 11
United Airlines San Francisco – London LHR – Copenhagen CPH – Zurich ZRH – San Francisco SFO