360 Day Amortization Calculator: See Every Payment, Right Down to the Interest Convention
Whether you mean a full 360 month schedule or a 360 day interest year, this tool builds the real numbers behind your loan, payment by payment.
Commercial and some business loans often use a 360 day year, while most consumer mortgages use 365. Check your loan documents if you're unsure.
Add any consistent extra amount you plan to pay toward principal, or leave at 0.
First year payment schedule
Two Loans Hiding Under One Search Term
People land on this page meaning one of two genuinely different things, and mixing them up leads to real confusion. Sometimes 360 day amortization simply means the classic 30 year mortgage, 360 monthly payments spread across three decades. Other times it specifically refers to how interest accrues day to day, using a 360 day year as the denominator instead of the true 365 or 366 days in a calendar year. This calculator handles both, letting you set your term in years while separately choosing your daily interest convention, so whichever definition brought you here, the math underneath is correct.
Why Dividing by 360 Instead of 365 Actually Matters
It sounds like a rounding footnote, but it isn't. Daily interest under a 360 day convention is calculated as rate divided by 360, while a 365 day convention divides by 365. Since 360 is a smaller number, each day's interest fraction is very slightly larger, which on a sizeable loan balance compounds into a real dollar difference over the life of the loan. This calculator runs your numbers under your chosen basis and shows you directly what switching to the other convention would have cost or saved, so the impact isn't just theoretical.
Reading Your Schedule Like a Loan Officer Would
Early in any amortized loan, the bulk of each payment goes toward interest rather than principal, since interest is calculated on a much larger remaining balance in the early years. As the balance shrinks, that ratio flips, and later payments chip away at principal far more aggressively. The pie chart above shows the full lifetime split between principal and total interest paid, while the year one schedule table shows exactly how that balance shifts from the very first payment onward.
What Extra Payments Actually Buy You
Adding even a modest extra amount to each monthly payment goes straight toward principal rather than future interest, which shortens the loan and reduces total interest paid by more than the extra amount alone would suggest, since every dollar of principal paid early stops accruing interest for every remaining month of the loan. The comparison box shows both the time saved and the total interest avoided if you've entered an extra payment amount.
A Note on International Loan Conventions
Day count conventions differ by country and lending institution, some markets default to Actual/365, others to 30/360, and still others use Actual/Actual. Because this calculator lets you toggle the day count basis directly and enter any currency amount, it works regardless of which convention your specific lender or country typically applies, as long as you confirm the correct basis from your loan agreement first.
Standards This Tool Follows
| Reference | How it's applied here |
|---|---|
| ISO 8601 | Your first payment date is entered and displayed in the unambiguous YYYY-MM-DD format |
| 30/360 and Actual/365 conventions | Both standard day count bases are supported and directly comparable |
| WCAG 2.1 AA | Every field is labeled, keyboard accessible, and contrast-checked |
Frequently Asked Questions
What does 360 day amortization actually mean?
It can mean a loan spread across 360 monthly payments, the standard 30 year term, or a loan using a 360 day interest year for daily accrual, which is why this calculator supports both interpretations.
How does a 360 day year change my interest compared to a 365 day year?
Dividing by 360 instead of 365 makes each day's interest slightly larger, and on a sizeable balance over a long term that small daily difference becomes a real dollar amount, which you can compare directly here.
Why do commercial loans often use a 360 day year while home mortgages usually don't?
The convention dates back to simpler manual arithmetic and tends to slightly favor the lender, which is part of why it persists in commercial lending while most consumer mortgages default to a 365 day basis.
Can I see how extra payments affect a 360 day amortized loan?
Yes, entering a recurring extra payment recalculates your full schedule and shows both the months saved and the total interest avoided.