"I think it will take up almost all of the next government's mandate, or at least the next three years" to rebuild, she said, a week before Sebastian Pinera, the country's president-elect, takes over.
Bachelet said Chile will have to ask the World Bank and other organisations for credit to help absorb the cost of the reconstruction effort.
Al Jazeera's Teresa Bo, reporting from the hard-hit city of Constitucion on Thursday, said some areas of Chile have been declared completely uninhabitable.
Al Jazeera's Teresa Bo reports Constitucion residents' complaints against the government
"Lots of people will have to be moved and this is probably going to be a very costly reconstruction for this country," she said.
"Key sectors of the Chilean economy have been affected, for example the wine proucing regions. But Chile has a fund that was created by its copper exports, so they have some money saved that they will probably use for this reconstruction.
"However, we do know that they will probably borrow money from international organisations."
Meanwhile, strong aftershocks struck Chile again, rocking the battered town of Concepcion and sending panicked residents fleeing.
Soldiers deployed in the city urged people to evacuate following Wednesday's temblors and the authorities issued a tsunami warning.
Reporting from Concepcion, Al Jazeera's Lucia Newman said there was pandemoniumeverywhere as people rushed to get to higher ground even though the city is quite far away from the sea, making the possibility of a tsunami very remote.
Appeal for calm
No damage or injuries were reported in the aftershocks that came as Bachelet called for calm and asked people to stop hoarding supplies and help with relief efforts.
Bachelet's statement came in the face of criticism that her government has been slow to respond to one of the world's most powerful earthquakes in a century.
Chilean emergency officials and the military have blamed each other for not clearly warning coastal villages of tsunamis immediately after Saturday's quake, angering survivors who lost relatives and friends in the massive waves.
The number of those killed by Saturday's magnitude 8.8 earthquake and the tsunami that followed is likely to increase as rescue workers continue search and recovery efforts amid the rubble of collapsed buildings.
Hundreds of people are still missing after the quake, which left an estimated 1.5 million homes damaged.
A curfew remained in place in Concepcion following the aftershocks, with thousands of troops patrolling the streets in devastated areas to keep order and oversee aid distribution.