Mortgage rates may no longer be at all-time lows, but they're still historically low — much, much lower than we've typically seen over the past several decades of record-keeping.

So, don’t think for a second that the opportunity to save a substantial stack of cash by refinancing has passed you by.

Though last year's cheap rates made 2020 a blockbuster for refinancing, millions of homeowners who've procrastinated on taking out new loans can still save hundreds of dollars a month by pulling the trigger on a refi, according to new research.

How much could a refi save you?

By many accounts refinance records were shattered in 2020, thanks to lower-than-ever mortgage rates resulting from the pandemic and its accompanying financial crisis.

Over October, November and December alone, lenders refinanced 2.23 million home mortgages — 71% more than during the final three months of 2019, says Attom Data Solutions.

But at least 13 million homeowners who haven't yet refinanced can still benefit substantially by swapping out their loans and scoring one of today's bargain mortgage rates.

They'd save an average $283 a month, according to a calculation from the mortgage technology and data provider Black Knight. In some states the savings would be even higher: California and New York homeowners could cut their monthly payments by $380, while in Virginia they could save over $320, on average.

A few million homeowners would make out even better. Black Knight says 2.5 million U.S. mortgage holders could save at least $400 a month by refinancing, while another 1.5 million could slash their monthly housing costs by $500 or more.

Are you a good refinance candidate?

Black Knight's data is based on mortgage rates from mid-April, when 30-year fixed-rate home loans dropped to an average 3.04% in the 50-year-old weekly survey from mortgage giant Freddie Mac. More recently, they were even cheaper — averaging 2.97% — and offered even more homeowners an incentive to refinance.

Generally, good refinance candidates hold 30-year mortgages and owe no more than 80% of the value of their homes, Black Knight says. They also have credit scores of at least 720, which is well above average. Not sure where your score sits? Today it's easy to check your credit score for free.

According to the study, a refi is worth your while only if you can shave at least three-quarters of 1 percentage point (0.75) off your current mortgage rate.

Thirty-year rates were averaging 3.8% or higher for much of 2019, meaning you may be eligible for a doozy of a refi even if you've had your current loan for under two years.

Removing all of its eligibility criteria, Black Knight says approximately 21 million mortgage holders could come out ahead by refinancing.

Time may be running out

With the economy improving and COVID-19 vaccinations already in the arms of more than 100 million Americans, the low-rate environment homeowners have been enjoying for much of the pandemic may not last much longer.

So if you’re considering a refinance, you'll want to get the ball rolling while you still have a good opportunity to save. Check mortgage rates from at least five lenders, because more than one study has found five is the magic number for finding the lowest rate available in your area and for a person with your credit score.

Maybe refinancing isn’t right for you at this particular moment. Don’t let that prevent you from pursuing other methods of bringing down your costs as a homeowner.

When it comes time to renew your homeowners insurance, get rate quotes from multiple insurers to make sure you're getting the coverage you need at the best possible price.

And, you could make a little extra money to help with your monthly house payments through a fairly effortless way of dabbling in the record-breaking stock market. A popular app helps you earn returns merely by investing "spare change" from everyday purchases.