Calculate amount financed
Start with purchase price, subtract down payment, then add or subtract any amounts financed under the specific loan. A percentage down payment should always be translated into dollars.
Model mortgage insurance explicitly
A down-payment threshold can affect whether mortgage insurance applies, but the rules and cancellation path vary by loan program. Use an actual lender estimate rather than assuming one universal threshold.
Protect post-closing liquidity
Compare the payment savings from more cash down with the emergency and repair cash that would remain. A smaller loan is useful, but an empty bank account creates a different risk.
Example: $400,000 purchase
A 10% down payment is $40,000 and leaves $360,000 before other financed items. A 20% down payment is $80,000 and leaves $320,000—a $40,000 reduction in principal, but also $40,000 more cash committed at closing.
What to check before you decide
- Mortgage-insurance rules vary by product and lender.
- A calculator does not replace a Loan Estimate or closing disclosure.
Sources behind this guide
These official and primary sources let you verify rules, definitions, and terms that may change.
CFPB — Decide how much to spend on a home↗CFPB — Tools for homebuyers↗