mac5155 wrote:without doing any calculations i'd think a 9% loan and a 6% loan at 10k each would have a similar total payment to a 20k loan at 7.5%

Of course. It would be identical. Imagine you you have two $10,000 loans---one at 5% one at 10%. The loan is due in 10 years with 120 equal payments. You'd pay the same through 120 equal payments on a 7.5%.

You could improve your situation. Say you wanted to pay the total debt off in 5 years. If you paid 60 equal payments on both loans, again your total interest would be the same as if you paid 60 payments on a 7.5%. Loan 1 (@ 5%) would be billed at payments like $120 and Loan 2 (@ 10%) would be billed at $150. (These numbers are totally made up). You could pay the debt off faster by doubling what is due---paying $240 on the 5% loan and $300 on the 10% loan. But you'd be much better served to pay $120 (the minimum) on the 5% loan and allocate the extra $120 to the 10% loan and pay $420 until it is gone. Once you pay off the 10% loan, return to the 5% loan and pay the $540 payments on that loan.

In both situations you pay $540 a month. But without consolidation you pay $120/$420 and pay off the loans quicker. With consolidation you make one continuous $540 payment, but you can't take advantage of allocating your payments.

Hope that makes sense.