The ideal debt to equity ratio is 2:1. This means that at no given point of time should the debt be more than twice the equity because it becomes riskier to pay back and hence there is a fear of bankruptcy. 

However, it is difficult to put a mark of ideal ratio since, the type, nature, and size of every business and industry is different. 

Further Readings – 

1. Capital Adequacy Ratio (CAR)
2. What Do You Mean By Line of Credit?
3. Non Performing Assets (NPA)
4. Types of Bonds