Street parking at night
Can be the cheaper answer if the paid hours have ended and the signs do not indicate another restriction. This is where checking the sign matters most.
Night Parking
Is parking free in Reykjavik at night?
Sometimes street parking in Reykjavik can be free outside the paid periods, depending on the zone and the day. But that does not mean every place becomes free at night, and it definitely does not mean garages stop charging.
Short answer
Street parking may become free when the paid period ends, but only if the exact street and zone allow it. Garages follow separate tariffs and often keep charging overnight, so do not apply street logic to a garage.
Garage parking at night
Usually the easier answer, but not the cheap answer by default. Several garages in Reykjavik operate on 24/7 charging schedules.
Downtown hotel stay
This is the situation where people most often overpay. If the car will sit still overnight, compare the full garage cost before choosing it automatically.
What to check before you assume parking is free
Check 1: the exact street sign and zone.
Check 2: whether you are on a street or in a garage.
Check 3: whether your hotel or host gave advice that matches the current posted rules.
What I would tell a friend
If you hear “parking is free at night,” treat that as a starting point, not a final answer. In Reykjavik, the expensive mistake usually comes from assuming a garage behaves like a street zone.