10/1 ARM Calculator 2026
Estimate your adjustable-rate mortgage payments – initial fixed period + annual adjustments
Our free 10/1 ARM calculator helps you forecast adjustable-rate mortgage payments after ten years of fixed rates. Use this calculator to see how extra payments or interest-only options impact your loan balance and long-term interest costs. Adjust each field to match your specific loan terms, and the totals will automatically update. If you're considering a shorter initial fixed period, compare results with our 7/1 ARM calculator or see how a 5/1 ARM mortgage compares.
Basic Loan Information
ARM Adjustment Details
Note: The boxes below are for illustration purposes. You may adjust the values to match your specific loan terms.
Note: The Margin + Index and Current Rate boxes are for illustration only. The payment results and schedule use your initial rate and caps, and update automatically when you change any loan input after the first calculation.
Margin + Index = Interest Rate
|
|
+
|
|
=
|
|
Current Interest Rate + Annual Cap = Interest Rate
|
|
+
|
|
=
|
|
Tip: Enter your lender's actual First Adjustment, Annual, and Lifetime caps (typically 5/2/5). The yellow formula box mirrors your Annual Cap, and the results below update automatically.
Optional Settings
Payment Summary
Initial Monthly Payment
Your fixed payment for the first 10 years
First Adjustment Payment
Year 11 payment (rate + first adjustment cap)
Maximum Payment
Highest payment (initial rate + up to lifetime cap)
Total Interest (Worst-Case)
Based on first adjustment, then annual increases up to the lifetime cap
Amortization Schedule (Worst-Case Scenario)
Shows rates increasing by your first adjustment cap at year 11, then your annual cap, up to the lifetime cap
| Year | Rate | Monthly Payment | Principal | Interest | Balance |
|---|
How to Find the Current Index Rate for Your 10/1 ARM
Understanding how your adjustable-rate mortgage is calculated doesn't have to be confusing. The boxes above show exactly how your new interest rate is determined: Index + Margin = Interest Rate. Here are the best sources for the index rate used by Fannie Mae and Freddie Mac:
Official Index Rate Sources
1. Federal Reserve Bank of New York (Official SOFR Source)
Secured Overnight Financing Rate (SOFR):
https://www.newyorkfed.org/markets/reference-rates/sofr-averages-and-index
Look for the 30-DAY AVERAGE (%). This is the index rate that Fannie Mae uses for most adjustable-rate mortgages. As of October 2026, the index rate is approximately 4.20%. The calculator above defaults to this SOFR rate.
2. Federal Reserve Bank of St. Louis (FRED)
1-Year Treasury Constant Maturity Rate:
https://fred.stlouisfed.org/series/DGS1
In the top-left corner, under "Observations," you'll see the current index rate. As of October 2026, the rate is 3.59%.
Pro Tip: Enter the index rate in the box above. Your lender will provide the margin - the additional percentage they charge - which remains fixed for the life of the loan. Index + Margin = Your Interest Rate.
Understanding Rate Caps on a 10/1 ARM
What happens if the index rate spikes? That's where rate caps protect you. Most 10/1 ARMs have a 5% first adjustment cap, a 2% annual adjustment cap, and a 5% lifetime cap (written 5/2/5), though these can vary by lender. Enter your loan's actual caps in the calculator above — the payment results and captions will update to match. Then review the worst-case amortization schedule to see how payments could adjust over time.
Important: When Does the Rate Adjust?
Ask the lender when the new interest rate is calculated. For example: The lender calculates the new rate at the end of the initial term (after 10 years for a 10/1 ARM), and the new rate will apply for the next adjustment period.
Is a 10/1 ARM Right for You?
This 10/1 ARM calculator is designed to help you clearly understand how an adjustable-rate mortgage works - and to give you the confidence to manage it wisely. Before committing to any ARM, review the pros and cons of a conventional loan to see if a fixed-rate mortgage might better suit your long-term plans.
You can also use our conventional loan monthly payment calculator to compare payment scenarios across different loan types. For different ARM terms, explore our 7/1 ARM calculator and 5/1 ARM calculator.
10/1 ARM Calculator FAQs
What is a 10/1 ARM mortgage?
A 10/1 ARM (Adjustable-Rate Mortgage) is a home loan with an interest rate that remains fixed for the first 10 years. After that, the rate adjusts annually based on a benchmark index, such as SOFR, plus a fixed margin.
How do rate caps work on a 10/1 ARM?
A 10/1 ARM typically has a 5% first adjustment cap, a 2% cap on each later adjustment, and a 5% lifetime cap (often written 5/2/5), though these can vary by lender. This means your rate can rise by up to 5% at the first adjustment after year 10, then up to 2% at each later adjustment, and never more than 5% above the starting rate over the life of the loan.
What index is used for a 10/1 ARM?
Most 10/1 ARMs use the SOFR (Secured Overnight Financing Rate) as the benchmark index. Fannie Mae also accepts the 1-Year Treasury Constant Maturity Rate. Your mortgage rate is calculated as Index + Margin.
Is a 10/1 ARM a good choice for me?
A 10/1 ARM can be a good choice if you plan to stay in your home for 10 years or less, expect your income to rise, or want lower initial monthly payments. However, it carries the risk of higher payments after the fixed period ends.
Connect With Us
Please share – it really helps