How to Calculate Loan Amount for a Hybrid Loan Structure
(Interest-Only + Amortization Period Explained)
Hey everybody, welcome to this short video where we’re going to explain how you can calculate your loan amount for a hybrid loan that consists of both an interest-only period and a traditional principal + interest amortization period.
In this example, we’re going to use six months of interest-only, followed by the normal amortization period for the remainder of the term.
My name is Anton Zjac, I’m with IntellCRE, and we work with hundreds of investors and agents every day. These are some of the recurring questions we receive around how to calculate certain metrics for hybrid loan products, so let’s jump right into it.
Understanding the Hybrid Loan Structure
In this example, we are using a hybrid loan that includes:
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A six-month interest-only period
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Followed by a classical amortization period for the remainder of the loan term
For the property, we assume the following inputs:
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NOI = Net Operating Income
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R = Interest Rate
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N = Amortization Term (in years)
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DCR = Debt Coverage Ratio
The Debt Coverage Ratio (DCR) is defined as:
DCR = NOI ÷ Annual Debt Service
Example of DCR
If a property has:
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NOI = $125,000
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Annual Debt Service = $100,000
Then:
DCR = 125,000 ÷ 100,000 = 1.25
This is the type of cushion lenders want to see — it shows there is enough income to safely cover debt payments.
How to Calculate the Loan Amount
Step 1: Convert the Interest Rate to a Monthly Rate
We convert the annual interest rate R into a monthly interest rate I:
I = R ÷ 12
Step 2: Build the Two Payment Streams
1) Interest-Only Payment Stream
During the interest-only period:
Monthly Payment = I × L
Where:
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I = monthly interest rate
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L = loan amount
This gives the monthly payment during the interest-only phase.
2) Amortization Payment Stream
Once amortization begins, payments include principal + interest:
Monthly Payment = L × C
Where C is the monthly amortization factor, calculated as:
C = I ÷ [1 − (1 + I)^(-n)]
Where:
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I = monthly interest rate
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n = total number of monthly payments
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n = years × 12
Step 3: Choose a Loan Sizing Convention
Lenders typically use one of two conventions:
Option A — First-Year Underwriting Convention
Loan sizing is based on the first year’s debt service, which includes:
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6 months of interest-only payments
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6 months of amortization payments
Annual Debt Service:
Year 1 ADS = L × (6I + 6C)
Option B — Post Interest-Only Convention (More Conservative)
Loan sizing is based on full amortization debt service after the interest-only period ends:
Post-IO ADS = L × (12C)
This is more conservative because it includes principal + interest for all 12 months.
Step 4: Solve for the Loan Amount (L)
Since:
DCR = NOI ÷ Annual Debt Service
We solve for L.
First-Year Underwriting Loan Amount:
L = NOI ÷ [DCR × (6I + 6C)]
Post Interest-Only Loan Amount:
L = NOI ÷ (DCR × 12C)
These formulas allow you to calculate loan amounts for hybrid loan structures.
Example Calculation
Given:
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NOI = $340,000
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DCR = 1.25
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Interest Rate = 6.5%
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Amortization Term = 30 years
Step 1: Monthly Interest Rate
I = 0.065 ÷ 12 = 0.0054167
Step 2: Amortization Constant (C)
C = I ÷ [1 − (1 + I)^(-n)]
Plugging in the numbers:
C = 0.006321
Step 3: Annual Debt Service Factors
First-Year Factor:
6I + 6C = 0.070437
Post-Interest-Only Factor:
12C = 0.075852
Step 4: Loan Amount Calculations
First-Year Underwriting Loan Amount:
L = NOI ÷ [DCR × (6I + 6C)]
L = 340,000 ÷ [1.25 × 0.070437]
L ≈ $3.86 million
Post-Interest-Only Loan Amount:
L = NOI ÷ (DCR × 12C)
L = 340,000 ÷ [1.25 × 0.075852]
L ≈ $3.58 million
Final Interpretation
These two methods produce slightly different loan amounts:
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First-year underwriting: $3.86M
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Post-interest-only underwriting: $3.58M
Most lenders use the more conservative approach, which is the post interest-only convention, because it reflects the debt service once principal payments begin.
So in most real-world cases, the lender would likely quote a maximum loan amount of $3.58M.
Final Thoughts
Loan sizing for hybrid loan products is something many investors struggle with. That’s why we’re creating resources like this — so you can:
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Understand your numbers
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Evaluate lender quotes accurately
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Structure deals more intelligently
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Analyze hybrid financing products confidently
We’ll be making more educational content like this.
If you found this helpful, make sure to like, subscribe, and follow for future content.
Thank you for reading — see you in the next one.
