The calculator tells you your DPS, but not your frames per second. Casters need the Focus stat, but they also need %Cast Speed gear. The calculator doesn't have a gear slot by default—remember that a slow cast animation (1.2 seconds) will get you killed even if your sheet DPS is 50k.
Furthermore, you have attribute points (Strength, Dexterity, Focus, Vitality) to distribute manually. Torchlight 2 Build Calculator