Enter the net operating income ($) and the debt service ($) into the Calculator. The calculator will evaluate the Mortgage Service Ratio. 

Mortgage Service Ratio Formula



  • MSR is the Mortgage Service Ratio ()
  • NOI is the net operating income ($)
  • DS is the debt service ($)

To calculate Mortgage Service Ratio, divide the net operating income by the debt service.

How to Calculate Mortgage Service Ratio?

The following steps outline how to calculate the Mortgage Service Ratio.

  • First, determine the net operating income ($). 
  • Next, determine the debt service ($). 
  • Next, gather the formula from above = MSR = NOI / DS.
  • Finally, calculate the Mortgage Service Ratio.
  • After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

net operating income ($) = 500

debt service ($) = 234