The average interest rate on refinanced student loans jumped up last week. For many borrowers, rates remain low enough to make refinancing a good option.

For borrowers with a credit score of 720 or higher who prequalified on Credible.com’s student loan marketplace from January 24 to January 28, the average fixed interest rate on a 10-year refinance loan was 3.64%. On a five-year variable-rate loan, the rate was 3.45%, according to Credible.com.

Related: Best Student Loan Refinance Lenders

Fixed-rate Loans

Last week, the average fixed rate on a 10-year refinance loan jumped by 0.08% to 3.64%. The average stood at 3.56% the week prior.

At this time last year, the average fixed rate on a 10-year refinance loan was 3.83%, or 0.19% higher than today’s rate. That means that borrowers who refinance now have the chance to lock in a rate that’s significantly lower than they would have received at this time last year.

A borrower who refinances $20,000 in student loans to today’s average fixed rate would pay around $199 per month and approximately $3,890 in total interest over 10 years, according to Low Cost Advisor’s student loan calculator.

Variable-rate Loans

Average variable rates on five-year refinance loans moved up last week, from 3.41% on average to 3.45%.

In contrast to fixed rates, variable interest rates fluctuate over the course of a loan term according to market conditions and the index they’re tied to. Many refinance lenders recalculate rates monthly for borrowers with variable-rate loans, but they typically limit how high the rate can go—to 18%, for instance.

Refinancing an existing $20,000 loan to a five-year loan at 3.45% interest would yield a monthly payment of approximately $363. A borrower would pay $1,803 in total interest over the life of the loan. But since the rate in this example is variable, it could go up or down from month to month within that time frame.

Related: Should You Refinance Student Loans?

Comparing Student Loan Refinancing Rates

One big goal of refinancing student loans, for many borrowers, is reducing the amount of interest paid. And that means getting the lowest possible interest rate.

Rates on variable loans may start out lower than rates on fixed-rate loans. Of course, because they’re variable, they’re subject to interest rate increases. You can limit the risk of interest rate increases with variable-rate loans by paying off your loan as quickly as possible. Still, if you like the reliability of a fixed payment, fixed-rate loans could be a better choice.

Regardless of whether you decide on a fixed- or variable-rate loan, it’s important to compare rates across multiple lenders to make sure you’re not missing out on possible savings. There’s a chance you could qualify for interest rate discounts by opting for automatic payments or by having an existing relationship with a lender.

When to Refinance Student Loans

Most lenders require borrowers to complete their degree before refinancing—though not all—so in most cases, wait to refinance until you’ve graduated. You’ll also need a good or excellent credit score and stable income in order to access the lowest interest rates.

Using a co-signer is one option for those who don’t have strong enough credit or income to qualify for a refinance loan. Alternatively, you could wait until your credit and income are stronger. If you decide to use a co-signer, make sure they’re aware that they’ll be responsible for payments if you’re not able to for some reason. The loan will also appear on their credit report.

Before you choose to refinance, calculate your potential savings. It’s important to make sure you’ll save enough to justify refinancing. Shop at multiple lenders for rates and consider your credit score when shopping around. Keep in mind that those with the highest credit scores receive the lowest rates.

Refinancing Federal Loans to Private Loans

There are a few things to keep in mind when refinancing a federal student loan into a private student loan. To begin, you’ll lose access to some benefits that federal student loans offer. For instance, you’ll no longer have access to income-driven repayment plans or deferment and forbearance options.

You may not need these programs if you have a stable income and plan to pay off your loan quickly. But make sure you won’t need these programs if you’re thinking about refinancing federal student loans.

If you do need the benefits of those programs, you could refinance only your private loans or just a portion of your federal loans.