Calculate the annual income that will be lost by the person (or you) dying, and the number of years that that income will be "missed" by the people left behind (survivors). Multiply these two figures and that gives you the total amount of money that will be "missing" or "needed" after your death. That is usually a good starting point. There are formulas to "discount" the annual shortfall over the number of years involved. Insurance agents have these discount factors readily available. Don't count on the survivor remarrying too soon, especially if you have children. Assume the longest period that the person will have to "get along without you," and try to cover that period of time. If you own a house, the mortgage should already be life insured, so that can often be deducted from your calculation.
Call an insurance agent, because each case needs to be looked at individually. There is no "right answer" to this one.
However, there are some right questions, and you just asked one. Best of luck.
There are various factors that determine the amount of insurance you need, such as: gross income, age, inflation, annual interest rate etc. You can refer to an online life insurance calculator that can assist you in determining the exact amount of coverage you need on life insurance policy.