Blended Rate Calculator
Calculate the weighted average rate across multiple loans, model your monthly savings from a refinance, and find the break-even point where refinancing costs pay for themselves.
Get Started in 3 Steps
How to Use the Blended Rate Calculator
Enter Your First Loan Details
Input the balance and annual interest rate of your primary loan — this could be your existing mortgage, a first lien, or a new purchase loan.
Add Your Second Loan
Enter the balance and rate of the second loan — a bridge, HELOC, seller carryback, or second mortgage — to model the combined obligation.
Review the Blended Rate & Payment
See your weighted average interest rate and combined monthly payment, giving you a single number to compare against alternative financing structures.
Blended Rate Calculator
Weighted average rate across all your outstanding debt
Loan Type
Current Balance
Current Rate
Portfolio Breakdown
Blended Rate
6.500%
Total Debt
$500,000
Loans
1
New Rate
Term
Rate Δ
▼1.001%
Current
6.500%
New
5.499%
Est. Monthly Payment
Current
$3,160
@ 6.50%
New
$2,839
@ 5.50%
$322
saved / mo
$3,861
saved / yr
$115,815
saved 30yr
Refinancing at 5.499% could save you $322/mo vs. your blended rate of 6.500%.
| Year | Principal | Interest | Balance |
|---|---|---|---|
| 1 | $6,737 | $27,327 | $493,263 |
| 2 | $7,117 | $26,947 | $486,147 |
| 3 | $7,518 | $26,546 | $478,629 |
| 4 | $7,942 | $26,122 | $470,687 |
| 5 | $8,390 | $25,674 | $462,297 |
| 6 | $8,863 | $25,201 | $453,434 |
| 7 | $9,363 | $24,701 | $444,071 |
| 8 | $9,891 | $24,173 | $434,180 |
| 9 | $10,449 | $23,615 | $423,731 |
| 10 | $11,038 | $23,026 | $412,693 |
| 11 | $11,661 | $22,403 | $401,033 |
| 12 | $12,318 | $21,745 | $388,715 |
| 13 | $13,013 | $21,051 | $375,702 |
| 14 | $13,747 | $20,317 | $361,955 |
| 15 | $14,522 | $19,542 | $347,433 |
| 16 | $15,341 | $18,723 | $332,092 |
| 17 | $16,206 | $17,857 | $315,885 |
| 18 | $17,120 | $16,943 | $298,765 |
| 19 | $18,086 | $15,978 | $280,679 |
| 20 | $19,106 | $14,958 | $261,574 |
| 21 | $20,183 | $13,880 | $241,390 |
| 22 | $21,322 | $12,742 | $220,069 |
| 23 | $22,524 | $11,540 | $197,545 |
| 24 | $23,794 | $10,269 | $173,750 |
| 25 | $25,136 | $8,927 | $148,614 |
| 26 | $26,554 | $7,510 | $122,060 |
| 27 | $28,051 | $6,012 | $94,009 |
| 28 | $29,634 | $4,430 | $64,375 |
| 29 | $31,305 | $2,759 | $33,070 |
| 30 | $33,070 | $993 | Paid off |
| Total | $500,000 | $521,907 | paid off |
*Monthly payment estimates assume a standard amortizing loan. Blended rate is weighted by outstanding balance. Savings projections are estimates only and do not include closing costs, fees, or prepayment penalties. Not a commitment to lend. · Lumen Mortgage Corporation NMLS #1498678
How do you calculate a blended mortgage rate?
A blended rate is the weighted average of two loan rates: multiply each loan's balance by its rate, sum them, then divide by the total balance. Example: $300,000 at 3.25% + $100,000 at 7.00% = 4.19% blended rate.
Best for: Borrowers evaluating piggyback loans, bridge financing, seller carryback deals, or assumption + second mortgage combos
How It Works
Understanding the Blended Rate Calculator
When you carry two loans simultaneously — a first mortgage and a HELOC, a primary loan and a seller carryback, or an existing mortgage and a bridge loan — the blended rate tells you your true combined interest cost as a single percentage.
Worked example: You're assuming a seller's 3.25% mortgage with a $280,000 remaining balance and taking a second lien at 7.50% for $120,000. Blended rate = ($280,000 x 0.0325 + $120,000 x 0.075) / $400,000 = ($9,100 + $9,000) / $400,000 = 4.525%. That's well below the current market rate of 6.75% for a new single mortgage — making the assumption + second lien strategy the clear winner.
Use this whenever you're evaluating split financing structures, and pair it with the Refinance Calculator to model the break-even point of consolidating both loans into one once rates drop.
Ready to apply?
Numbers look right? Explore our Refinance Loans page for eligibility details, rates, and next steps.
About This Calculator
What the Blended Rate Calculator is For
Two scenarios where this calculator earns its keep: refinancing and bridge loans. For refinancers, enter your current loan balance and rate alongside the proposed new terms to see your exact monthly savings, total closing cost recovery timeline, and lifetime interest reduction. For bridge loan borrowers, combine your existing mortgage, the bridge itself, and the new purchase loan to see your blended rate and total monthly obligation during the interim period — the number that determines whether the strategy is actually affordable.
Common Use Cases
- Calculating refinance monthly savings and break-even timeline
- Modeling the combined rate and payment during a bridge loan period
- Deciding whether the cost of refinancing is justified by the savings
Ready to turn numbers into a loan?
Common Questions
Blended Rate Calculator — Frequently Asked Questions
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All calculator results are estimates for informational purposes only and do not constitute a loan commitment or guarantee of any specific rate or terms. Actual loan terms will depend on creditworthiness, property type, and market conditions. Lumen Mortgage Corporation · NMLS #1498678 · Licensed in Oregon & California · 920 SW 6th Ave, Suite 1200, Portland, OR 97204.