NEW YORK (CNN/Money) - If you're part of a dual-income household and you have children, buying life insurance on both earners is an obvious must. Should one of you die, neither one of you would want to leave your dependents without some kind of replacement income.

But if your family relies on two parents and only one income, you're facing different life insurance needs. Of course you need life insurance for the breadwinner, but it's equally important to think about insuring the stay-at-home partner.

"I would absolutely recommend life insurance on a non-income-producing spouse to families at every income level," said David Hardinger, a CFP and MSFS with American Express Financial Advisors in Cedar Rapids, Iowa.

Rick Butts, an electrical engineer in The Colony, Texas, couldn't agree more. Three years ago, at the suggestion of Wayne Smith, a CFP with American Express Financial Advisors, he took out as much life insurance on his wife as he did on himself. She was a stay-at-home mom and home-schooled 5 of their 6 children.

Calculators       • Which is better: Term or whole life? • How much life insurance do I need?

Tragically, she died from complications just three days after giving birth to their seventh child, Anna. Butts' older children -- four girls and two boys -- are now 16, 13, 11, 9, 6, and 4. Anna is now 1. He's grateful for the financial help the life insurance policy provided: he didn't have to put his children through a move or drastic lifestyle changes, which would have only added to the pain of losing their mom.

"I was able to tell them: we don't have to move, you can do the same sporting activities and so on, and it's made the transition for them so much easier," Butts said. "When these things happen, your lifestyle is in place. I can tell you that it happened so quickly. Buying a policy is like buckling your safety belt. It's just not something you can do after the fact."

Insurance agents and financial planners stress that all couples with one member in the work force and one member who stays at home should consider buying life insurance on the non-income-producing partner. That holds true whether the person is male or female and whether they intend to return to the work force or not and even if the couple isn't legally married.

"There are intangibles that cannot be replaced financially, of course, but the person at home provides an extraordinarily valuable service to the family. Life insurance is definitely something to consider," said Jeanne Salvatore, a spokesperson for the Insurance Information Institute.

Life insurance can cover tangible services that a stay-at-home spouse provided, especially important if the remaining spouse is left with the sole responsibility of caring for children or elders, said Herb Perone, a spokesperson for the American Council of Life Insurers.

"Insuring a non-incoming-producing spouse contributes profoundly to a family's financial well-being," said Perone. "People don't often realize the enormous financial benefit of a non-working spouse. After the person has died, they're forced to make a calculation as they find themselves paying for a nanny, a chauffeur, someone who balances the checkbook, and so on."

The untimely death of a non-income-producing spouse also could result in dramatic career changes for the remaining spouse, said Bob Dehais, a vice-president at Met Life Financial Services. He or she could end up working and earning less, to care for dependents. Life insurance on a non-income-producing spouse could help compensate for that lost income.

Butts said he tried working for a few weeks after his wife died, but it was too much to handle with so many small children.

"In four or five years, when the younger ones get a little older, I can see myself going back to work," he said. "But right now, I'm able to stay at home and school the kids myself. Because of the policy, we basically have no real financial concerns."

It depends, of course.

"Very rarely do customers wake up one day and say oh, I better get some life insurance," said Dehais. "The real question is what they want it to do for them. Younger families are usually more concerned with keeping the family going. More mature families might use life insurance as a vehicle in which to pass a substantial amount to heirs on an income-tax free basis."

Dehais recommends sitting down with a trusted financial advisor to establish the value of the policy. To start getting at a dollar number, Hardinger creates a cash flow model for his clients to estimate how much having a non-income-producing parent contributes financially to the family.

"If you eat out once a week now, you might do it two or three times if the person is not there. Then you have to think about the cost of child care, housekeeping, or other services the person might provide. You input those things as cash flow items, add in the various costs, and project that out for as long as dependents are there," Hardinger explained.

More subtle costs must be included too. If money goes to expenses that weren't there before, Hardinger explained, then you must also account for lost savings. And, of course, the figures must be adjusted for inflation and for the length of time dependents might need benefits.

Then, it's time to think about a specific product.

"I usually don't suggest a specific product until we determine what the family's need is," Hardinger said. "Maybe you need term insurance, because the need is temporary. On the other hand, maybe the need is permanent, and a different product might work better."

A term life insurance policy simply pays death benefits if you die; a cash value policy also accumulates net worth for you, Dehais explained.

"A cash value policy pays a death benefit if you die, but is also an investment: in the future you can access that money along with earnings if you don't," Dehais said. "Some non-income-producing spouses like cash value policies because they allow them to accumulate assets in their own names."

Again, one size never fits all. For more about specific types of life insurance, read Money 101: Life Insurance.