Nearly half of those who died were civilians, the Syrian Observatory for Human Rights said.
The Britain-based watchdog said it has documented the killing of around 82,257 people, including 34,473 civilians -- among them 4,788 children and 3,049 women.
It has also recorded the deaths of 16,687 rebel fighters, including defected military personnel.
The watchdog said 16,729 soldiers and more than 12,000 shabiha (pro-regime militia) and regime informants have also died.
The bodies of another 2,368 people were found across Syria, the Observatory added.
Some 1.4 million people have fled the country while 4.2 other Syrians have become internally displaced, the UN says.
The Observatory says its toll does not include more than 10,000 people missing in detention in regime jails, or some 2,500 pro-regime prisoners kept in rebel hands.