Police officials say the attacks started on Tuesday morning when a parked car exploded in Mahmoudiya, killing five people. The town is about 30 kilometres (20 miles) south of the Iraqi capital.
The officials say a suicide car bomb later struck near a security checkpoint in the northern Baghdad suburb of Taji, killing six. Another explosion in the northwestern neighbourhood of Shula killed four people.
Medics in a nearby hospital confirmed the casualties. All officials spoke on condition of anonymity because they are not authorized to speak to the media.
Violence has fallen since the peak of insurgency in Iraq several years ago, but lethal attacks still occur frequently.