An off-route recalculation method and apparatus for a navigation system calculates a new route when a vehicle is deviated from an originally calculated route to a destination. The method is comprised of the steps of: detecting whether a user vehicle has deviated from an originally calculated route; predicting a path that a user is likely to take until a new route to the destination is calculated; calculating a predicted distance that the user vehicle advances through the predicted path during a time the new route to the destination is calculated and during a turn prepare time, thereby determining a start position of the new route; calculating the new route to the destination incorporating the start position.