Calculate interest-only mortgage payments, payment shock when the IO period ends, total interest costs, and compare with traditional amortizing loans.
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Interest-only loans offer lower initial payments but come with significant risks. When the IO period ends (typically 5-10 years), your payment can double or triple. Our calculator shows exactly what you'll pay during and after the interest-only period, helping you understand if this loan type fits your financial situation.
An interest-only mortgage allows you to pay only the interest for an initial period (typically 5-10 years), after which the loan converts to a fully amortizing mortgage for the remaining term. During the IO period, your payment is significantly lower, but you're not building equity through principal payments. Once the IO period ends, you must pay both principal and interest over a shorter remaining term, resulting in substantially higher payments.
Interest-Only Payment Formula
IO Payment = Principal × (Annual Rate / 12)The biggest risk of IO loans is payment shock—the dramatic increase when you start paying principal. Calculate exactly how much your payment will jump so you can plan ahead.
IO loans typically cost more in total interest because you're not paying down principal early. See the true cost difference vs. a traditional amortizing loan.
IO loans work best with a clear plan: sell before IO ends, refinance, or prepare for higher payments. This calculator helps you understand all scenarios.
Real estate investors often use IO loans to maximize cash flow. Compare the interest savings vs. opportunity cost of investing the difference.
Maximize rental cash flow during the hold period. Plan to sell or refinance before the IO period ends. The lower payments improve debt-service coverage ratios.
If you're confident you'll sell within 5-7 years (job relocation, growing family), IO loans reduce your monthly outlay without long-term commitment.
Doctors, lawyers, and others with expected significant income growth may benefit from lower payments now, planning to handle higher payments later.
When buying a new home before selling the old one, IO loans minimize carrying costs during the transition period.
IO loans are more common for jumbo mortgages where monthly payments would otherwise be very high. They're often used for luxury properties.
Payment shock is the increase in your monthly payment when the IO period ends. For example, on a $500,000 loan at 7% with a 10-year IO period, your payment jumps from about $2,917/month to roughly $4,500/month—a 54% increase. This calculator shows your exact payment shock.
During the IO period: Loan Amount × (Rate/12). A $400,000 loan at 7% = $2,333/month. Compare to roughly $2,661/month for a traditional 30-year loan. The $328 savings comes at the cost of building no equity.
They can be strategic for the right borrower: investors maximizing cash flow, short-term owners planning to sell, or high earners expecting income growth. They're risky if you have no exit plan or can't afford the higher post-IO payments.
Your loan converts to a fully amortizing mortgage for the remaining term. On a 30-year loan with 10-year IO period, you have 20 years to pay off the full principal plus interest. This shorter amortization dramatically increases monthly payments.
Yes! Making extra principal payments during the IO period reduces your balance and future payment shock. Even small extra payments can significantly impact your post-IO payment. Use our 'Extra Principal' field to see the effect.
IO periods are commonly 5, 7, or 10 years, with total loan terms of 30 years. Some lenders offer 15-year IO periods. After the IO period, you'll have 20-25 years to amortize the remaining balance.
Yes, but they're less common than before 2008. They're primarily offered for jumbo loans, investment properties, and high-net-worth borrowers. Qualification requirements are stricter—expect to need excellent credit (720+), significant assets, and usually 20%+ down payment.
Typically 15-30% more total interest over the life of the loan. On a $500,000 loan at 7% over 30 years, an IO loan (10-year IO period) costs roughly $100,000+ more in interest than a traditional amortizing loan.
Yes, refinancing is a common exit strategy. However, you'll need sufficient equity and favorable rates. If property values drop or rates rise, refinancing may not be possible or beneficial. Always have a backup plan.
Avoid IO loans if: you plan to stay long-term without income growth, you can barely afford the IO payment (let alone post-IO), you have unstable income, or you're using it solely to buy more house than you can afford.