Finance category
Mortgage, loan, investing, tax, and money calculators.
Mortgage Rate Lock Calculator
Compare your locked mortgage rate against where the market sits now. Include any lock extension fee to see the true net savings or cost from locking when you did.
Net savings from lock
$24,177
over the life of the loan
Locked payment
$2,628
6.875%
Floated payment
$2,695
+$67/mo over locked
Extension cost
$0
if 0-day extension needed
Reading the number
Locking saved money — even after extension fees, the locked rate is cheaper than what you'd be paying by floating.
Lock decisions trade certainty for cost. A 30-day lock is usually free; longer locks (45/60/90 days) and extensions cost real money. Match the lock period to your expected close date with a small buffer.
How to Use
- Enter the loan amount and term.
- Enter the rate you locked.
- Enter today's available rate (or what your lender would offer if you re-locked).
- If you needed to extend the lock, enter the extension fee per 30 days and the days extended.
- Read the net savings or cost over the life of the loan.
Frequently Asked Questions
How long do lock periods last?
Standard locks run 30, 45, or 60 days. Longer locks (75/90/120 days) cost more upfront. Most refinances close inside 30 days; new construction may need a long lock or a float-down option.
What's a float-down option?
A feature on some locks that lets you re-lock at a lower rate one time before close, usually for a fee or rate adjustment. Useful when you're worried about rate volatility but want upside if rates drop.
What does a lock extension cost?
Typically 0.125–0.25% of loan amount per 15–30 days of extension. On a $400k loan that's $500–$1,000 per extension. Plan close dates carefully to avoid extensions.
Can I cancel a lock if rates drop?
Sometimes — but it usually means walking away from the lender or paying a re-lock fee. Some lenders offer one free float-down. Most do not let you cancel and re-lock for free.
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If you re-lock during a refi, run break-even on the new costs.
Closing Cost vs Rate Calculator
Trade closing costs for a lower locked rate or vice versa.
ARM vs Fixed-Rate Calculator
If rate volatility worries you, consider an ARM with a planned exit.
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