Down Payment Calculator

Before you calculate

Use this calculator when you want to compare how upfront cash, home price, selected closing costs, down payment percentage, interest rate, and loan term interact before reviewing lender documents. Use Mortgage Payment for a focused principal-and-interest payment, Mortgage for broader housing-cost assumptions, House Affordability for income and debt constraints, and actual Loan Estimates, lender disclosures, local tax sources, insurer quotes, title or settlement statements, HOA documents, or assistance-program materials for official figures.

Formula summary

In Home Price mode with percentage closing costs, the app solves homePrice as upfrontCashAvailable / ((downPaymentPercent + closingCostPercent) / 100). With fixed closing costs, it solves homePrice as max(0, upfrontCashAvailable - closingCostAmount) / (downPaymentPercent / 100). In Cash Needed mode, downPaymentAmount equals homePrice * downPaymentPercent / 100 and cashNeeded equals downPaymentAmount plus selected closing costs. In Down Payment Percentage mode, downPaymentAmount equals max(0, upfrontCashAvailable - closingCosts), then downPaymentPercent equals downPaymentAmount / homePrice * 100 when home price is positive. Loan amount is max(0, homePrice - downPaymentAmount). Monthly payment uses the fixed-rate PMT formula with interestRate / 100 / 12 and loanTermYears * 12.

Worked example

Example: three ways to frame the same purchase cash question

With the default Home Price inputs, $100,000 upfront cash, 20 percent down, and 3 percent closing costs support an estimated $434,782.61 home price, $86,956.52 down payment, $13,043.48 closing costs, $347,826.09 loan amount, and $2,198.50 monthly principal and interest at 6.5 percent over 30 years. In Cash Needed mode, a $500,000 home with 20 percent down and 3 percent closing costs needs $115,000.00 upfront cash and produces a $400,000 loan amount with a $2,528.27 monthly principal-and-interest estimate. In Down Payment Percentage mode, $100,000 cash for a $500,000 home with 3 percent closing costs leaves $85,000.00 for down payment, or 17.00 percent down, with a $415,000 loan amount and $2,623.08 monthly principal-and-interest estimate.

The examples show how the same cash, price, and closing-cost assumptions can answer different planning questions. They are not cash-to-close disclosures, lender approvals, PMI determinations, affordability recommendations, tax answers, or personal homebuying advice.

Assumptions

• The selected solve mode determines which question is answered. Inputs that remain in the form state can still be present in server-rendered HTML, but the calculator uses the mode-specific formula branch for home price, cash needed, or down payment percentage. Closing costs are a simplified entered percentage of home price or a fixed entered amount; the estimate does not model lender credits, seller credits, earnest-money deposits, points, prepaid interest, escrow deposits, title fees, appraisal fees, recording fees, transfer taxes, program fees, or any other actual cash-to-close adjustment.
• The monthly payment output is principal and interest only. It excludes property tax, homeowners insurance, mortgage insurance premiums, escrow, HOA dues, maintenance, utilities, assistance-program requirements, underwriting, rate locks, APR, lender approval, and official Loan Estimate or Closing Disclosure figures. The PMI notice uses a simple below-20-percent branch for educational context; real private mortgage insurance, FHA mortgage insurance premiums, VA funding fees, USDA guarantee fees, jumbo-loan overlays, lender-paid PMI, cancellation, and product eligibility depend on lender, agency, insurer, and program rules.
• Package fixtures cover all three solve modes, and internal independent comparator checks may be used only as validation evidence. CFPB Loan Estimate materials are needed before copy discusses loan amount, closing costs, cash to close, projected payments, lender credits, taxes, or insurance; CFPB PMI materials are needed before discussing conventional-loan PMI context; CFPB principal-and-interest versus total monthly payment materials are needed before explaining monthly-payment boundaries; and Regulation Z section 1026.37 is needed before legal Loan Estimate disclosure claims. Results are educational estimates, not financial, tax, legal, lending, mortgage, consumer-rights, regulatory, or personalised advice.

Common mistakes to avoid

• Treating the down payment as the whole cash-to-close amount. The app adds only the selected closing-cost assumption, while real closing can include deposits, credits, prepaid items, escrow funding, title charges, taxes, insurance, and program fees.
• Reading the monthly payment as a full housing payment. The output is a principal-and-interest estimate on the modeled loan amount, not a total monthly payment with tax, insurance, mortgage insurance, HOA dues, or escrow.
• Treating the 20 percent PMI notice as a binding rule. It is a simplified conventional-loan signal, not a lender, insurer, FHA, VA, USDA, jumbo, cancellation, or assistance-program determination.

Methodology and sources

This calculator is an original implementation based on the app's documented down-payment solve modes, selected closing-cost assumptions, fixed principal-and-interest payment math, deterministic fixtures, edge cases, rounding policy tests, and internal validation. It is not copied from a single source.

Outputs are checked with deterministic fixtures for home-price, cash-needed, and implied down-payment-percentage solves, plus edge-case tests and internal validation artifacts. The result remains an educational estimate, not a Loan Estimate, not a Closing Disclosure, not a cash-to-close figure, not a PMI determination, not a lender quote, not an approval, not a tax answer, not a legal answer, not an assistance-program eligibility result, and not personalised mortgage advice.

Formula version 2026.05.22-generic-down-payment-modes. The version marks the calculation logic and validation fixture set used for this estimate.

• CFPB Loan Estimate and compare Loan Estimates materials should be used before copy discusses official loan amount, projected payments, closing costs, estimated cash to close, lender credits, taxes, insurance, rate locks, lender forms, or mortgage-offer comparisons.
• CFPB private mortgage insurance materials should be used before copy discusses conventional-loan PMI context, 20 percent down payment framing, PMI payment forms, PMI cost, or PMI alternatives.
• CFPB principal-and-interest versus total monthly payment materials should be used before copy explains why the app's monthly payment output excludes taxes, homeowners insurance, mortgage insurance, escrow, HOA dues, or total monthly housing-payment items.
• CFPB Regulation Z section 1026.37 plus lender disclosures should be used before copy discusses legal Loan Estimate disclosure fields, cash-to-close calculations, down payment and funds from borrower, closing-cost financing, disclosure timing, or disclosure accuracy.
• FHA, VA, USDA, Fannie Mae, Freddie Mac, lender, mortgage-insurer, title or settlement, local tax authority, insurer, HOA, legal, and assistance-program sources are needed before copy makes product-specific, jurisdiction-specific, mortgage-insurance, tax, escrow, title, eligibility, underwriting, approval, or legal claims.

Estimate only

The result is educational and is not financial, tax, legal, lending, investment, or regulated advice. Real provider terms, fees, rates, taxes, and personal circumstances can change the final answer.

Formula and help: read the full down payment calculator methodology notes.

Related reading

• Mortgage payments in plain English
• How Calcs.finance validates calculator formulas
• Estimate limitations and not-advice disclaimer

When another calculator fits better