Is a simple income multiple good enough?

It can be a reasonable starting point, and it is the roughest of the recognized methods. An income multiple ignores what you owe, what you already have set aside, and any group life coverage through work, so it can land well above or below the real gap. A needs analysis such as the DIME method accounts for those components, though it too produces a gross figure before existing assets are deducted. Any of these gives a starting range rather than an answer, so review your individual needs with a licensed agent or qualified advisor.