ARM Loan Calculator

ARM Loan Calculator

Adjustable-rate mortgages offer lower initial rates that adjust periodically based on market conditions.

What This Calculator Shows

• Monthly Payment: Your expected payment amount based on loan terms
• Total Interest: The cost of borrowing over the loan lifetime
• Amortization Schedule: How payments split between principal and interest
• Payment Breakdown: Visual representation of your loan costs

How to Calculate

1. Enter your loan amount 2. Input the interest rate (APR) 3. Select the loan term 4. Review your payment details and total costs

Key Considerations for ARM Loan

• Compare offers from multiple lenders before committing
• Understand all fees including origination, closing costs, and prepayment penalties
• Consider how rate changes might affect your payments (for variable rates)
• Factor in your overall financial goals and debt-to-income ratio

An adjustable-rate mortgage fixes the rate for an initial period and then adjusts periodically against an index. A 5/1 ARM is fixed for 5 years then adjusts annually; 7/6 is fixed for 7 then every 6 months.

Caps limit the movement, and they are the numbers to read:

Cap	Meaning	Typical
Initial	Maximum first adjustment	2%
Periodic	Maximum per later adjustment	2%
Lifetime	Maximum above the start rate	5%

A 2/2/5 cap on a 6% start rate means the worst case is 8% at the first adjustment and 11% eventually.

Rate	Payment on $400,000
6% (start)	$2,398
8% (first adjustment cap)	$2,935
11% (lifetime cap)	$3,809

Take an ARM only if you can afford the lifetime cap payment. "I'll refinance before it adjusts" assumes rates and your circumstances both cooperate, which is what made 2008 so expensive for so many people.

The Numbers This Page Opens With

The calculator above starts at $400,000 over 30 years at 6%, which is representative for this product:

Monthly payment	$2,398
Total repaid	$863,353
Total interest	$463,353
Interest as a share of principal	116%

Change any input above and every figure recalculates. The amortisation formula behind it:

`` M = P × [ r(1+r)^n ] / [ (1+r)^n − 1 ]

P = principal, r = monthly rate (annual ÷ 12), n = number of payments ``

Before You Sign

• Compare APR, not the rate. APR includes origination and points; the rate does not.
• Ask about prepayment penalties. They turn a plan to pay early into a fee.
• Rate-shop inside 14 days. Credit scoring models treat multiple mortgage or auto

enquiries in that window as one enquiry.

• Check whether the payment includes escrow. A mortgage quote without taxes and insurance

understates the real monthly cost by hundreds.

Where the Money Goes

On $400,000 at 6% over 30 years, paying $2,398 a month:

Point	Principal repaid	Interest paid	Balance
Year 3	$15,664	$70,672	$384,336
Year 8	$45,121	$170,718	$354,879
Year 15	$115,805	$315,872	$284,195
Year 23	$226,535	$420,980	$173,465
Year 30	$400,000	$463,353	$0

Early payments are mostly interest. That is not a fee structure — it is arithmetic: interest accrues on the outstanding balance, which starts at its largest. It is also why an extra payment made early saves far more than the same payment made late.

What a Rate Change Costs

Rate	Monthly	vs 6%	Total repaid
5.00%	$2,147	-$251	$773,023
5.50%	$2,271	-$127	$817,616
6.00%	$2,398	—	$863,353
6.50%	$2,528	+$130	$910,178
7.00%	$2,661	+$263	$958,036

Half a percentage point moves the monthly payment by $130 and the total by $46,825. Shopping three lenders usually beats any amount of negotiating on price.