If you have a first mortgage plus a HELOC, home equity loan or another mortgage, comparing the rates separately can make it harder to see what you're paying across the full balance.
Our blended rate calculator combines those loans into one balance-weighted interest rate, giving you a cleaner benchmark for comparing your current debt with a potential refinance.
How to Use the Blended Rate Calculator
Enter the current balance and interest rate for each home loan you want to include. The calculator weights each rate based on the size of its loan balance, so a $300,000 first mortgage has more influence on the result than a $50,000 HELOC.
If you have fewer than four active loans, leave the unused loan balances at $0. Those loans will not be included in the calculation.
Blended Rate Calculator Basics
| Input |
What It Means |
Why It Matters |
| Loan balance |
The current principal balance of each mortgage, HELOC or home equity loan |
Larger balances have more influence on the blended rate |
| Interest rate |
The current interest rate on each active loan |
The calculator uses the rate and balance together to estimate each loan's share of annual interest |
| Active loans |
The home loans you want included in the comparison |
Only loans with a balance above $0 affect the blended rate |
| Blended rate |
The balance-weighted interest rate across all included loans |
Provides one benchmark for comparing your existing loans with another financing option |
What Is a Blended Mortgage Rate?
A blended mortgage rate is a weighted average of the interest rates on two or more home loans. Instead of giving every rate equal weight, it accounts for how much money you actually owe at each rate.
That distinction is important. Suppose you have a $300,000 first mortgage at 6% and a $30,000 home equity loan at 9%. A simple average of 6% and 9% would be 7.5%, but that would exaggerate the effect of the much smaller second loan.
The blended rate gives the $300,000 mortgage 10 times as much weight as the $30,000 loan because its balance is 10 times larger.
You can use the same calculation for a first mortgage plus a HELOC, a first mortgage plus a home equity loan, or several active home loans.
How the Blended Rate Is Calculated
The calculator multiplies each loan balance by its interest rate, adds those weighted amounts together and divides the result by the combined loan balance.
In simplified form:
Blended rate = Total of each loan balance × its rate ÷ Total loan balances
For example, suppose you have:
- A $300,000 first mortgage at 6.5%
- A $75,000 HELOC balance at 8.5%
The first mortgage represents $19,500 of annualized interest at its current balance and rate:
$300,000 × 6.5% = $19,500
The HELOC represents $6,375:
$75,000 × 8.5% = $6,375
Together, that's $25,875 across a combined $375,000 balance.
$25,875 ÷ $375,000 = 6.90%
The blended mortgage rate is therefore 6.90%.
This calculation is a rate comparison. It does not mean the two loans behave like one $375,000 mortgage at 6.90%.
Why a Blended Rate Is Useful for a Mortgage and HELOC
A common use for a blended rate is comparing a low-rate first mortgage with a higher-rate HELOC.
Suppose you locked your first mortgage several years ago at a relatively low rate, then later borrowed against your equity with a HELOC. Looking only at the HELOC's higher rate can make refinancing both loans seem more attractive than it actually is because most of your debt may still be sitting in the lower-rate first mortgage.
The blended rate puts the two balances together.
If your first mortgage is much larger than the HELOC, its rate will dominate the calculation. If the HELOC balance grows, the higher rate has more influence on your combined result.
This can provide a useful starting point when deciding whether to keep the two loans or investigate refinancing into one mortgage.
Blended Rate vs. a Simple Average
A blended rate should not be calculated by adding your mortgage rates together and dividing by the number of loans.
Consider a $400,000 mortgage at 6% and a $50,000 HELOC at 10%.
A simple average would be:
(6% + 10%) ÷ 2 = 8%
But the two balances are nowhere near equal. The first mortgage represents almost 89% of the combined debt.
The balance-weighted calculation produces a blended rate of about 6.44% instead.
That is a much more useful representation of the interest rates attached to the $450,000 combined balance.
Blended Rate vs. APR
Your blended mortgage rate is not an annual percentage rate, or APR.
A blended rate only weights the interest rates on the balances entered into the calculator. It does not incorporate the upfront costs or fees of obtaining those loans.
The CFPB explains that APR incorporates the interest rate plus certain loan fees and provides another way to compare borrowing costs.
If you are considering refinancing, do not compare a new loan's APR directly with the calculator's blended interest rate as though they measure the same thing. Compare the proposed interest rate, APR, closing costs, monthly payment and expected holding period separately.
When a Blended Rate Can Help With a Refinance Decision
The calculator can give you a baseline before you compare your current loans with a refinance offer.
Suppose your first mortgage and HELOC produce a 6.90% blended rate and you receive a refinance quote at 6.50%. The new rate is lower, but that alone does not establish that refinancing saves money.
The refinance can have closing costs. It can change how long you remain in debt. It can also change the speed at which you repay principal.
If your existing first mortgage has only 20 years remaining and you refinance both loans into a new 30-year mortgage, for example, the lower interest rate comes with a longer repayment schedule unless you make additional payments.
A useful comparison therefore starts with the blended rate but goes further. Compare:
- The current combined balances
- The blended interest rate
- The current monthly payments
- The proposed refinance rate and APR
- Refinance closing costs
- The remaining terms on your current loans
- The term of the new mortgage
- How long you expect to keep the new loan
The CFPB recommends comparing the interest rate, monthly payment, upfront loan costs and other terms when evaluating mortgage offers.
How a Variable-Rate HELOC Affects Your Blended Rate
A blended rate is only a snapshot based on the rates you enter.
This is particularly important when one of the loans is a HELOC. The CFPB notes that HELOCs usually have variable interest rates.
If the HELOC rate changes, your blended rate changes too, even if your first mortgage rate remains fixed.
For example, a $300,000 first mortgage at 6.5% combined with a $75,000 HELOC at 8.5% produces a blended rate of 6.90%. If that HELOC rate later rises to 10%, the blended rate rises to 7.20%, assuming the balances stay unchanged.
The HELOC balance can move as well. Drawing another $25,000 at the higher HELOC rate gives that loan more weight in the combined calculation.
Update the calculator when either the HELOC rate or outstanding balance changes if you want a current comparison.
What the Blended Rate Calculator Cannot Tell You
The calculator gives you a useful weighted interest rate, but it is not a complete loan-cost comparison.
It does not calculate:
- Your combined monthly payment
- APR
- Refinance closing costs
- Points or lender fees
- How quickly each loan amortizes
- Future HELOC rate changes
- Changes in your HELOC balance from future draws
- How much interest you will pay over the remaining life of each loan
Two sets of loans can have the same blended rate and very different monthly payments or long-term costs because their terms and repayment structures are different.
A HELOC also has a draw and repayment structure that does not behave like a standard fixed-rate mortgage. Payments can change as the balance, rate and phase of the line change.
The Bottom Line
A blended rate calculator gives you one balance-weighted interest rate across a first mortgage, HELOC, home equity loan or other active home loans. It is more useful than simply averaging the rates because it accounts for how much you owe on each loan.
Use the blended rate as a starting point when comparing multiple existing loans with a potential refinance. Then compare the monthly payments, APR, closing costs, remaining loan terms and future rate risk before deciding whether replacing the loans would actually reduce your borrowing costs.
Frequently Asked Questions
What Is a Blended Interest Rate on a Mortgage?
A blended mortgage rate is a balance-weighted average of the interest rates on multiple home loans. A larger loan balance has more influence on the blended rate than a smaller balance.
How Do You Calculate a Blended Mortgage Rate?
Multiply each loan balance by its interest rate, add the resulting amounts together and divide by the combined balance of all included loans.
Can You Calculate a Blended Rate for a Mortgage and HELOC?
Yes. Enter the outstanding first-mortgage balance and rate along with the current HELOC balance and rate. The calculator weights each rate according to its balance.
Can You Include a Home Equity Loan in a Blended Rate?
Yes. A home equity loan can be included along with a first mortgage, HELOC or other home loan as long as you enter its current principal balance and interest rate.
Is a Blended Mortgage Rate the Same as APR?
No. A blended rate weights the interest rates on multiple loan balances. APR is a broader measure that incorporates the interest rate and certain borrowing costs. They should not be compared as though they are the same metric.
Does the Blended Rate Show My Monthly Payment?
No. Monthly payments depend on each loan's balance, rate, remaining term and repayment structure. Two loan combinations can have the same blended rate but different monthly payments.
Does a HELOC Rate Change the Blended Rate?
Yes. If your HELOC has a variable rate, a change in that rate changes the blended rate. A change in the amount you have borrowed from the HELOC can also move the result.
Can I Use a Blended Rate to Decide Whether to Refinance?
It can provide a useful starting point, but it does not determine whether refinancing will save money. Compare the new rate and APR with your existing loans, then account for closing costs, monthly payments, loan terms and how long you expect to keep the refinance.
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