Bell said he suffered the strain during Monday's workouts at the Peoria Sports Complex, the first day of workouts for San Diego pitchers and catchers.
"It should only be three or four days," said Bell, who had his calf heavily wrapped Tuesday morning. "It feels a lot better today than it did yesterday."
Bell didn't express much concern over the injury, especially since he won't miss critical time during camp. The Padres don't play their first Spring Training game until Feb. 26.
Bell has more saves (89) over the past two seasons than anyone else in baseball and, obviously, was an important cog in the best bullpen -- statistically speaking, at least -- in the Major Leagues a year ago.