This link should take you to my Google Docs page with my Dough Hydration calculator spreadsheet that you can down-load and use. Unfortunately, it does not translate into GoogleDocs format at all well so you will need Excel to use it.
You can enter numbers in the cells to the left of the slider bars or you can use the slider bars to adjust the values. Using the TAB key between entries takes you to the next entry cell.
If you have a recipe that you want to scale up or down, the Yellow cell in the right hand panel is where you enter the required dough mass. The scaled results appear in the chart bars. If you dont require the starter mass to be scaled, there is a check box that will hold it constant.
The hydration calculations are done for Total Flour Weight (TFW) ie the content of the starter is taken into account. The salt content is fixed at 1.8%.
Hope you find it useful and that the system works.
Any feed-back, particularly high praise, will be appreciated.