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The 30-year mortgage rate has risen rapidly to its highest level since 2019, around 4%.

The increase could compel home shoppers to look for houses in lower price ranges. Some might need to get preapproved again.

Mortgage rates have risen almost a full percentage point since late December.

Rising rates reduce one's buying power. Let's say you can afford $2,000 a month in principal and interest on a mortgage.

If you started looking at homes before Christmas, when the 30-year mortgage was around 3%, you could have borrowed about $474,400 to get a $2,000 monthly payment.

But with a mortgage rate of 4%, you could get a $418,900 loan with that same $2,000 a month in principal and interest. That's a reduction in affordability of about $55,500.

Rates went up so fast that the effects may feel shocking and disheartening. Here's what would-be buyers can do to increase their chances of success:

Update the preapproval

Many buyers are encouraged to get mortgage preapproval letters, which describe how much the buyer is qualified to borrow at a certain interest rate. But when rates go up as quickly as they have in recent weeks, preapproval letters go out of date.

Even when a preapproval letter says it's good for 60 to 90 days, "that's really not relevant in a rising rate scenario, and you need to talk to your mortgage loan officer again," says Shashank Shekhar, CEO of InstaMortgage.

Adjust the price range

Higher rates may mean "you have to scale back somewhat," says Jim Sahnger, a loan officer in South Florida for C2 Financial Corp. "If you want a pool, you don't get a house with a pool. Or you look at a house that isn't as renovated, but you know you'll take care of it in time."

Find other ways to decrease your payment

If you have spare cash, you may have other options besides reducing your price range, says David Kuiper, vice president of mortgage lending for Northpointe Bank in Holland, Michigan. You may be able to pay discount points to get a lower rate, he says.

Or you might pay off some of your outstanding debts to improve your debt-to-income ratio, he says. This can increase the maximum monthly mortgage payment that you would be eligible for.

Remember it could be worse

In Freddie Mac's weekly rate survey, the 30-year mortgage averaged 4.09% in the 2010s, 6.29% in the 2000s, 8.12% in the 1990s and 12.71% in the 1980s. The average rate topped out at 18.63% in October 1981, and people still bought houses in those days.

Holden Lewis writes for NerdWallet.