An LTV ratio is your current principal balance divided by either the original property value or the current appraised value. The original value is the lower of the sales price or appraised value.
For example, if the current principal loan balance is $135,000, the appraised value is $175,000, and the sales price was $182,000, then the current LTV ratio is equal to:
Current Principal Balance / Original Property Value = $135,000 / $175,000 = 77.1%