FreeCalculators

Mortgage Rate Lock Decision Tool

Easily decide whether to lock your mortgage rate or float. Analyze costs and make informed choices with our intuitive decision tool.

Loans & Mortgage · Reviewed by FreeCalculators Editorial · Updated 2026-09-01

How it works

The Mortgage Rate Lock Decision Tool helps you determine whether to lock in your mortgage rate or let it float based on market conditions. The tool utilizes the PMT formula to calculate your monthly payments at the current rate and potential future rates. For example, if you have a loan amount of $300,000 at a current rate of 6.5% for 30 years, your monthly payment would be approximately $1,896. If you expect the rate to drop by 12.5 basis points, you can calculate the new payment based on the anticipated lower rate. Conversely, if the rate rises, the tool shows the increased monthly payment. The break-even analysis helps you understand how many basis points the rate would need to move for the decision to lock to be beneficial. This is calculated by dividing the lock fee by the loan sensitivity per basis point. By inputting your specific numbers, you can make an informed decision about locking in your mortgage rate.

Formula


                Monthly payment = PMT at rate for term. Break-even = fee value ÷ loan sensitivity per bp.
              

Tips

  • Consider the current market trends and economic indicators before deciding to lock your rate.
  • Calculate your break-even point to understand how much the rate must change to justify not locking.
  • Always factor in your personal financial situation and risk tolerance when making your decision.
  • Stay updated on mortgage news and forecasts to better anticipate rate movements.

Frequently asked questions

What happens if I float my mortgage rate?
If you float your mortgage rate, you risk potential increases in interest rates, which could lead to higher monthly payments.
How is the break-even point calculated?
The break-even point is calculated by dividing the lock fee by the loan sensitivity per basis point, which helps you determine how much the rate must move to make locking worth it.
What is the impact of a 12.5 basis point drop in rates?
A 12.5 basis point drop can lower your monthly payment significantly; for example, a drop from 6.5% to 6.375% could save you around $20 per month on a $300,000 loan.
Are there any fees associated with locking my mortgage rate?
Yes, some lenders may charge a lock fee; in this tool, the default lock fee is set to $0, but check with your lender for their specific fees.