Blended Rate Calculator
Combine two loans into one weighted blended rate so you can compare keeping both against refinancing into a single mortgage.
By Onias Derilus, Mortgage Capital · NMLS# 1859012 · Last Updated: June 2026
The blended rate is the single average rate across both loans, weighted by balance. Use it to compare keeping two loans against refinancing into one. Estimate only.
A blended rate is the single average interest rate across two loans, weighted by how much you owe on each. It tells you the true effective rate on your combined debt.
It matters most when you are deciding whether to refinance. If a new single-loan rate is higher than your blended rate, consolidating could cost you more even if the new rate looks lower than your second loan.
How to Use This Calculator
- 1
Enter the balance and rate of your first mortgage.
- 2
Enter the balance and rate of your second loan or HELOC.
- 3
Read the blended rate across both balances.
- 4
Compare that blended rate to any single refinance offer before consolidating.
The Formula & Assumptions
Blended rate =
(B1 × R1 + B2 × R2)
÷ (B1 + B2)
B = balance, R = rate
Each loan rate is weighted by its share of the total balance, so a large low-rate first mortgage pulls the blended rate down even if a small second loan has a high rate.
The combined monthly interest is the sum of each balance times its rate, divided by twelve. It shows the interest portion only, not full principal-and-interest payments.
If you are weighing a cash-out refinance that replaces both loans, compare the new rate to this blended rate, not just to your highest-rate loan.
Frequently Asked Questions
Why does a blended rate matter for refinancing?
If you have a low first mortgage and a higher second loan, your blended rate may already be lower than a new single-loan rate. Refinancing both into one loan could raise your effective rate, so the blended rate is the number to beat.
Should I keep my second mortgage separate?
Often yes, when your first mortgage carries a much lower rate than current market. Replacing both with one new loan throws away that cheap first-loan rate. Compare the blended rate to any consolidation offer first.
Does the blended rate include my payment?
No. The blended rate is just the weighted average interest rate. Your actual payments depend on each loan term and amortization, which you can check with the mortgage payment calculator.
Can I blend more than two loans?
The math extends to any number of loans by weighting each balance by its rate and dividing by the total. This tool covers the two most common, a first mortgage plus a second loan or HELOC.
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Rates are illustrative only. APR and payments vary by credit score, loan amount, and market conditions. Subject to credit approval. Not a commitment to lend. NMLS# 1859012. Equal Housing Lender.