Fixed vs Variable Interest Rates
Last updated: June 2026
The core difference
A fixed rate is locked in for the whole term. Your payment never changes, which makes budgeting simple and protects you if market rates rise. A variable rate (sometimes called adjustable or floating) is tied to a benchmark, so it falls when rates drop and climbs when they rise. The lender shifts interest-rate risk onto you in exchange for a usually-lower starting rate.
What you're really choosing
The decision is about who carries the risk. With a fixed rate, the lender bears the risk that rates rise, so they charge a small premium for the certainty. With a variable rate, you accept the uncertainty in return for a lower introductory cost — a good deal if rates stay flat or fall, a painful one if they spike.
A worked example
On a $250,000 mortgage:
- A fixed 6.5% gives a steady payment of about $1,580 for 30 years.
- A variable loan might start at 5.5% (about $1,419) — saving $161 a month at first.
- But if the rate later resets to 8%, the payment jumps to roughly $1,834 — $254 more than the fixed option.
The variable loan wins early and could lose badly later. Whether that trade is worth it depends on how long you'll keep the loan and how much payment increase you could absorb.
How to decide
- Choose fixed if you value predictable payments, plan to keep the loan a long time, or rates are historically low.
- Consider variable if you'll repay or sell before the rate can reset much, or you have room in your budget to absorb increases.
Always check the cap — the maximum a variable rate can rise — and model the payment at that worst-case rate before committing.
Use the calculator
Put these ideas to work with the Payment Calculator. You can also browse all MoneyCalcKit calculators or read the calculator methodology for formulas and assumptions.
Frequently asked questions
Is a fixed or variable rate cheaper?
Variable rates usually start lower, but can rise. Fixed rates cost a little more up front in exchange for certainty. Which is cheaper overall depends on how rates move.
What is a rate cap?
A cap limits how much a variable rate can increase, per adjustment and over the life of the loan. Always model your payment at the cap before choosing a variable loan.
Can I switch from variable to fixed later?
Often yes, by refinancing — but that has its own costs. Factor potential refinancing fees into the comparison.