Interest Only
Calculator
Calculate your IO payments, compare total interest, and explore full amortization schedules — instantly.
| Period | Payment | Principal | Interest | Balance |
|---|---|---|---|---|
| Enter loan details above to see schedule | ||||
How Does an Interest-Only Loan Work?
An interest-only (IO) loan lets you pay just the interest for an initial period — typically 3 to 10 years. Your principal balance doesn't decrease during this time. When the IO period ends, payments jump to cover both principal and interest over the remaining term.
Interest-Only Payment Formula
Example: $250,000 × 5.0% ÷ 12 = $1,041.67/month
Principal & Interest Payment Formula
After the IO period, the remaining balance amortizes over the remaining term:
PMT = payment | PV = balance | i = monthly rate | n = months remaining
Step-by-Step Example
- Loan: $250,000 at 5% over 30 years, 5-year IO period.
- IO Phase (months 1–60): $1,041.67/month — interest only, no principal repaid.
- P&I Phase (months 61–360): Amortize $250,000 over 300 months → ~$1,491.72/month.
- Payment jump: +$450.05/month when IO period ends — plan ahead.
Frequently Asked Questions
Interest Only Calculator (Calculate Monthly Payment Instantly + Chart)
Before taking out a loan, you may estimate your monthly interest-only payment using our free, user-friendly interest only calculator. This calculator provides a quick overview of your payments throughout the interest-only period.
Whether you are considering an interest-only mortgage, HELOC, or another loan type, this tool helps you understand your financial position before speaking with a lender or comparing different loan scenarios.
By entering just three key inputs—loan amount, interest rate, and loan term—you can instantly see your interest-only monthly payment and make smarter borrowing decisions.
What Is an Interest-Only Loan?
An interest-only loan is a type of financing where you only pay interest on the borrowed amount for a set period. During this time, your principal balance does not decrease.
After the interest-only period ends, the loan converts into a standard repayment structure where you pay both principal and interest. This results in higher monthly payments.
How to Calculate Interest-Only Payments
To calculate your monthly interest-only payment, you need three things:
- Loan amount (principal)
- Interest rate (annual)
- Loan term
Divide the annual interest rate by 12 to get the monthly rate, then multiply it by the loan amount.
Our calculator performs this instantly so you can test different scenarios and compare results easily.
Example Calculation
If you take a $400,000 loan at 5% interest:
- Monthly rate = 5% ÷ 12 = 0.416%
- Monthly payment ≈ $1,833
After the interest-only period, payments increase because you begin repaying the principal.
Pros of Interest-Only Loans
- Lower monthly payments during the initial period
- Better cash flow for investors
- Flexible repayment options
Cons of Interest-Only Loans
- No principal reduction during IO period
- Higher total interest over time
- Payment shock after IO period ends
When Should You Use an Interest-Only Loan?
Interest-only loans may be suitable for:
- Property investors planning to sell early
- Borrowers expecting future income growth
- Freelancers or business owners with variable income
They are generally not ideal for long-term homeowners focused on building equity.
Interest-Only vs Principal & Interest
- Interest-Only: Lower payments, higher long-term cost
- Principal & Interest: Higher payments, builds equity
Interest-Only vs. Principal & Interest: At a Glance
| Feature | Interest-Only Loan | Principal & Interest Loan |
|---|---|---|
| Monthly Payment | Lower (interest only) | Higher (interest + principal) |
| Principal Reduction | None during IO period | Yes, from day one |
| Long-Term Cost | Higher overall | Lower overall |
| Risk | Higher after IO period ends | Lower, predictable |
| Best For | Investors, short-term owners | Long-term homeowners |