Current Mortgage Rates -- September 21: Rates Remain Competitive

Today's mortgage rates remain very competitive. Should you lock in at today's low rates?

Mortgage rates have been very competitive in recent months, presenting homebuyers with the opportunity to secure a home loan at a historically low rate. Today is no exception with average mortgage rates for Sept. 21 remaining below 3.00% for a 30-year fixed-rate mortgage loan and below 2.50% for a 15-year loan. Here's what you need to know about today's rates.

Data source: The Ascent's national mortgage interest rate tracking.

30-year mortgage rates

The average 30-year fixed mortgage rate today is 2.938%, up slightly compared with Friday's average rate of 2.934%.

At today's rate, you would have a monthly payment of $418 in principal and interest for every $100,000 you borrow. Because this is a fixed-rate loan, your rate and payment will not change for the life of the loan At this interest rate, you would pay a total of $50,576 in interest for each $100,000 borrowed. However, taxes and insurance will be additional and should be factored in when determining the affordability of borrowing.

20-year mortgage rates

The average 20-year fixed mortgage rate today is 2.972%, also up a bit compared with Friday's average rate of 2.883%. At today's average rate, the monthly principal and interest payment would total $553 per $100,000 borrowed.

While the average rate on a 20-year fixed rate mortgage is slightly higher than the average rate on a 30-year loan, monthly payments will be much higher but total interest costs much lower. When you repay your loan a decade earlier, you'll save substantially on interest but will need to make higher monthly payments to pay off the loan on schedule. Interest costs will come in at just $32,767 per $100,000 borrowed.

15-year mortgage rates

The average 15-year fixed mortgage rate for Sept. 21 is 2.414%, which is a very slight increase compared with Friday's average rate of 2.412%. At today's average rates, your monthly principal and interest payment would total $663 per $100,000 borrowed.

As with a 20-year loan, monthly payments are much higher for a 15-year loan than a 30-year loan, even though the interest rate is lower. These higher monthly payments occur because you are paying off your loan in half the time. The interest savings is substantial, with interest costs coming in at $19,295 for each $100,000 borrowed.

5/1 ARMs

The average interest rate for a 5/1 ARM is 3.456%, so unlike the other rates this is down a bit from Friday's average rate of 3.654%.

Also unlike the other mortgages on this list, a 5/1 ARM does not have a fixed interest rate. Instead, your starting interest rate will be locked in for five years, after which time rates can adjust once annually.

Because the 5/1 ARM has a higher starting rate than the 30-year fixed-rate loan, borrowers should not take the risk of rates adjusting upward after five years. Instead, homeowners would be better served by choosing a 30-year fixed-rate mortgage to ensure they can repay their loan in full at today's record-low low rates.

Should I lock my mortgage rate now?

A mortgage rate lock guarantees you a certain interest rate for a specified period of time -- usually 30 days, but you may be able to secure your rate for up to 60 days. You'll generally pay a fee to lock in your mortgage rate, but by doing so, you're protected if rates climb between the time you lock in and the date you close on your loan.

If you plan to close on your home within the next 30 days, it likely pays to lock in your mortgage rate based on today's rates -- especially since they're very low at this time. But if your closing is more than 30 days away, you may want to choose a floating rate lock instead. While there's usually a higher fee, a floating rate lock could save you money in the long run by allowing you to secure a lower rate on your mortgage if rates fall prior to your closing. While today's rates are still quite low, we don't know if rates will go up or down over the next few months so it pays to:

• LOCK if closing in 7 days
• LOCK if closing in 15 days
• LOCK if closing in 30 days
• FLOAT if closing in 45 days
• FLOAT if closing in 60 days

To make sure you secure the most competitive rate before locking in, you should shop around and get at least three different rate quotes. You can easily compare rates and terms from the best mortgage lenders to maximize the chances of securing the most affordable loan for your situation.