Continue your plan
Useful next calculations
When to use this calculator
- Before comparing mortgage products, brokers or repayment types.
- When you want to test how a different deposit, rate or term changes the payment.
- When you need a quick estimate before using a formal illustration or agreement in principle.
- When you are stress-testing your budget against a higher rate.
A realistic US planning example
Use these sample inputs as a quick scenario test, then change one variable at a time to compare outcomes.
| Input | Value |
|---|---|
| Loan Amount ($) | $280,000 |
| Fixed Rate (%) | 5% |
| Variable Rate (%) | 5% |
| Term (Years) | 25 years |
After entering these figures, review fixed, variable and difference together rather than in isolation. Then rerun the tool with one input adjusted.
How to read your results
Fixed
The figure produced by this output for the inputs you entered. Change one variable at a time if you want to see what drives it.
Variable
The figure produced by this output for the inputs you entered. Change one variable at a time if you want to see what drives it.
Difference
The figure produced by this output for the inputs you entered. Change one variable at a time if you want to see what drives it.
Method & assumptionsAuthoritative sources
This calculator compares the total cost of a fixed-rate mortgage against a variable or tracker mortgage over a chosen time horizon. For the fixed rate, the monthly payment and total cost are straightforward to calculate and remain constant throughout the comparison period. For the variable option, the calculator uses the current rate to project costs, with an optional rate-rise scenario so you can stress-test your budget. The comparison period is important: if it does not align with the end of a fixed deal, exit costs may apply. The tool does not model rate changes dynamically over time, and actual tracker costs will depend entirely on how the central bank base rate moves. This is a planning tool, not a guarantee of future costs.
Common mistakes
- !Mixing up loan amount and property value, which distorts affordability and LTV.
- !Using a headline rate but forgetting fees, insurance or repayment type.
- !Testing only one term length instead of comparing payment and total cost together.
- !Treating the result as a lender decision rather than a planning estimate.
What to do next
- Run a second scenario with a cautious assumption so you can see the downside clearly.
- Compare the result with the related calculators below before making a decision.
- Check current local rules, eligibility and provider terms before applying or committing money.
- Keep a record of the assumptions so you can update the estimate when a quote, bill or pay figure changes.
Frequently asked
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