Calculate your combined loan to value (CLTV) ratio

A = Decide how much you need.
B = Add the balances of all your existing mortgages.
C = Estimate your home’s value.

Use this formula to calculate your combined loan to value ratio:
(A + B)/C=CLTV

In other words, add the value of how much you need to the amount of your combined mortgage values, then divide that total by your home’s estimated value.