Fixed vs Floating Interest Rates: Which Should You Choose?

Fixed and floating (variable) interest rates are the two main rate structures for loans, mortgages, and investments. Each has distinct advantages and risks, and the right choice depends on your financial situation, risk tolerance, and expectations about future interest rate movements. This comparison examines both rate types and provides a framework for choosing.

How fixed rates work

Fixed rates remain constant for the entire term of the loan or investment. A 30-year fixed mortgage at 6.5% will have the same interest rate, and therefore the same monthly payment, for all 30 years. Fixed rates provide predictability and protection against rising rates but typically start higher than equivalent floating rates.

How floating rates work

Floating rates (also called variable or adjustable rates) change periodically based on a reference rate like SOFR (Secured Overnight Financing Rate), prime rate, or LIBOR (being phased out). The rate is typically expressed as reference rate plus a margin, e.g., SOFR + 2.5%. When the reference rate changes, your interest rate and payment change accordingly. Floating rates typically start lower than fixed rates but carry the risk of increasing.

Historical performance

Historically, borrowers with floating rates have paid less interest on average than those with fixed rates, because floating rates start lower and rate increases do not always materialize. However, this average masks significant variance: in periods of rising rates, floating rate borrowers can pay dramatically more. During the 2008 financial crisis, many borrowers with adjustable-rate mortgages saw payments double or triple when rates reset upward, contributing to widespread defaults.

Decision framework

Choose fixed rates when:

• You value predictability and cannot afford payment increases
• You expect interest rates to rise
• You plan to hold the loan long-term
• You are risk-averse
• Current rates are historically low

Choose floating rates when:

• You can absorb payment increases if rates rise
• You expect interest rates to fall or remain stable
• You plan to pay off the loan quickly (before rates can rise significantly)
• The initial rate discount is substantial (typically 0.5%+ below fixed)
• You are financially sophisticated and monitor rates actively

Hybrid options

Many mortgages offer hybrid structures: 5/1 ARMs (fixed for 5 years, then adjustable annually), 7/1 ARMs, 10/1 ARMs. These provide initial rate stability at a lower rate than fully fixed, with adjustment risk deferred. Hybrids make sense if you expect to move or refinance before the fixed period ends. Use the sevi.fun Loan Calculator to compare scenarios.