Blended Rate Mortgage Calculator
Weighted-average rate across multiple loans.
Calculate the blended (weighted-average) interest rate across two mortgage loans of different balances and rates. Free and educational.
What this tool does
Enter two loan balances and their rates. The tool shows the blended rate across both — the effective rate you are paying on total debt.
Enter Values
Formula Used
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Disclaimer
Results are estimates for educational purposes only. They do not constitute financial advice. Consult a qualified professional before making financial decisions.
Blended rate is what you are effectively paying when you hold two loans. 200,000 at 3% plus 50,000 at 7% is not 5% — the larger low-rate loan dominates. Actual blended rate is 3.80%. This is the number that matters when comparing against a single refinance offer.
A worked example
Try the defaults: loan 1 balance of 200,000, loan 1 rate of 3%, loan 2 balance of 50,000, loan 2 rate of 7%. The tool returns 3.80%. You can adjust any input and the result updates as you type — no submit button, no reload. That's the real power here: seeing how sensitive the output is to one or two assumptions.
What moves the number most
The result responds to Loan 1 Balance, Loan 1 Rate, Loan 2 Balance, and Loan 2 Rate. Not every input has equal weight. Flip one at a time toward extreme values to feel which ones move the needle most for your situation.
The formula behind this
Weighted average of the two rates by balance. Simple version ignores differing remaining terms — use equal remaining terms for cleanest comparison. Everything the calculator does is shown in the formula box below, so you can check the math against your own spreadsheet if you want.
Why this matters before you sign
A mortgage is usually the biggest single financial commitment a person makes. The difference between a well-chosen product and a hasty one can run into tens of thousands over the life of the loan. Running the numbers here before committing is the cheapest form of due diligence available.
What this doesn't capture
The figure excludes arrangement fees, valuation costs, legal fees, insurance, and any early-repayment charges — those can add several thousand to the headline cost. Rate changes at renewal for fixed-term deals will shift the picture further. Use this for the core interest/principal math and add the other costs on top.
Blended rate produces a weighted-average percentage based on the inputs provided.
Inputs
This example uses typical values for illustration. Adjust the inputs above to match a specific situation and see how the result changes.
Sources & Methodology
Methodology
Weighted average of the two rates by balance. Simple version ignores differing remaining terms — use equal remaining terms for cleanest comparison.
References
Frequently Asked Questions
When is this useful?
Does term length matter?
Is blended rate the same as APR?
Can I use this for more than 2 loans?
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