Starting Strength Warm-Up Calculator

Update: Here is a Spreadsheet that generates your complete SS Routine including the warm-up sets.

Found this Starting Strength Warm-Up Calculator Spreadsheet.
Of course it’s not just applicable to Starting Strength, but for every lifting workout.

Instructions
1) Follow the link.
2) Select the “File” button in the left hand corner.
3) From the drop-down menu select “Copy spreadsheet.”
4) Click “OK” on the Dialog Box.

Enter your working weight and you get the set/rep scheme for the squat bench press, deadlift, overhead press and the power clean

Or, as a commenter on reddit pointed out,

The idea, for all lifts except the dead lift, is to take your working weight minus the bar (20kg/45 lbs) and use this as the weight to add. Then follow the scheme below:

2×5 with just the bar
1×5 with bar + 25% of weight to add
1×3 with bar + 50% of weight to add
1×2 with bar + 75% of weight to add
3×5 at full working weight

And the dead lift is similar except you only perform single sets and instead of subtracting the bar, you subtract the bar plus two 45lb plates (135lb).