Mortgage Comparison
Fixed vs Variable
Mortgage Calculator
Avg 2-Year Fix
4.62%
Base Rate
4.50%
Should you lock in a fixed rate or take a variable deal? Enter your mortgage details and model what happens if rates rise or fall. See both options side by side with total cost over the full term, including what happens when the fixed period ends and you move to the SVR.
Mortgage Details
Assumes you don't remortgage when fix ends
Fixed rate wins on total cost
You save £0 over the full term
Fixed Rate
Variable / Tracker
How the fixed vs variable mortgage calculator works
Enter your mortgage amount, term and the rates for each option. The calculator models the full term for both scenarios. For the fixed option, it calculates payments at your fixed rate for the chosen period, then assumes you revert to the SVR for the remaining term. For the variable option, it starts at the current tracker/variable rate and applies your chosen rate change scenario after the same period.
This matters because most borrowers focus on the initial monthly payment but forget about the SVR cliff. A 2-year fix at 4.5% on £250,000 costs £1,390/month, but when you fall onto a 6.5% SVR your payment jumps to £1,691. Modelling the full term reveals the true cost difference between the two strategies.
Use the rate change dropdown to stress-test different scenarios. What if rates rise 1%? What if they fall 0.5%? The calculator recalculates both options instantly so you can make an informed decision. For a more detailed breakdown of your mortgage payments, use our mortgage calculator or remortgage calculator.
Frequently asked questions
Should I fix my mortgage rate in 2025?
It depends on your risk appetite and how long you plan to stay in the property. Fixing gives you certainty — your payments stay the same regardless of Bank of England base rate changes. In 2025, 2-year fixes sit around 4.5-5% and 5-year fixes at 4-4.5%. If you believe rates will rise, fixing protects you. If rates fall, you miss out on savings unless you remortgage early (which may incur ERCs).
What happens when my fixed rate ends?
When your fixed rate period ends, you automatically move to your lender's Standard Variable Rate (SVR), which is typically 1-2% higher than the best available deals. Your monthly payments will jump significantly. You should start looking for a new deal 3-6 months before your fix expires.
Is a tracker mortgage better than a fixed rate?
A tracker follows the Bank of England base rate plus a fixed margin (e.g. base rate + 0.75%). It can be cheaper than a fix when rates are falling but more expensive when rates rise. Trackers suit borrowers who are comfortable with payment fluctuations and have financial buffer to absorb increases.