How do you figure out how much is paid back to creditors in a Chapter 13?

The amount that creditors receive in a Chapter 13 depends upon a number of factors.  The first factor is what type of creditor are they?  Are they a secured creditor, secured by either real estate or a vehicle or some other item?  Or are they an unsecured creditor such as a credit card, a medical bill, a personal loan or a debt for some type of service?  Depending on what type of creditor will dictate to what amount they are paid back.  General unsecured creditors can be paid as little as 10% on the dollar or they can be paid back 100%, depending upon the particular case.  Secured creditors are paid back either the entire amount owed or in some cases the market value of their item plus an insurance risk percentage factor.
The main determination on whether or not a creditor is paid back 100% or 10% is the actual income and expenses of the debtor.  The trustee will examine the income of the debtor based upon the information provided by the debtor such as paycheck stubs, tax returns and any other proof of income.  The trustee will then examine the expenses of the debtor based upon reasonable customary expenses in addition to any exceptional expenses that the debtor may have.  The difference between the income and the expenses per month is what is required under the Bankruptcy Code to be paid to the Chapter 13 trustee each month.  It is from that amount that the trustee can then make disbursements.  In some cases, creditors will get paid back in full.  In most cases, creditors will get paid back less than in full, somewhere between 10% to 50% on the dollar.