There are a few ways to measure this.
You have a certain income and payments, money going in, money going out. A standard process is to evaluate and see if your cash flow can be altered to make it easier.
Another measure is to see where the money goes, is there a big external drain. Sometimes a persons blood pressure shows normal yet they have trouble making ends meet. Both are important and each has a unique course of action.
The first might be fixed fairly easily, the latter may involve a life style change.