How long did it take Odysseus to return home?

It takes Odysseus 20 years to return home after he left Ithaca for the war.

It takes Odysseus 10 years to return home after the 10 year long Trojan war.

During these 10 years, Odysseus spent a year with the sorceress Circe. Odysseus was trapped with the Nymph Goddess Calypso for 7 years.